Al111 Alton, P. B., 2011. How useful are plant functional types in global simulations of the carbon, water, and energy cycles?. J. Geophys. Res. G, 116: G01030.    Al111.pdf      

Abstract: Land-surface and vegetation models divide the globe into discrete vegetation classes or plant functional types (PFTs). The current study quantifies some of the limitations of this simplification on global predictions of carbon, water, and energy fluxes. First, a state-of-the-art land-surface model, JULES-SF, is optimized against a diversity of calibration data sets (eddy covariance fluxes, field measurements of net primary production (NPP), and remotely sensed surface albedo) in order to retrieve a range of values for four key plant parameters within each PFT. This is done for 112 sites and 1200 1 degrees land points. Second, global simulations are compared in which the parameter values per PFT are either fixed (standard method) or vary according to either the retrieved parameter range or the satellite-observed range (new methods). Retrieved key plant parameters exhibit a broad range, and the range overlap between PFTs is significant. The impact on the global simulation depends on the surface flux/state in question. Thus, the difference between the new and old method is small for albedo, net shortwave radiation, and continental runoff (0.005, 0.7\%, and 2\%, respectively) compared to current model-observation differences (0.05, 7\%, and 20\%, respectively). In contrast, carbon fluxes are more sensitive to the categorization of plant properties, with predicted global NPP varying by <= 15\% (6.2 Gt yr(-1)) according to whether the standard or one of the new methods is implemented.

Am001iw Amiro, B. D. and Barr, A. G. and Barr, J. G. and Black, T. A. and Bracho, R. and Brown, M. and Chen, J. and Clark, K. L. and Davis, K. J. and Desai, A. R. and Dore, S. and Engel, V. and Fuentes, J. D. and Goldstein, A. H. and Goulden, M. L. and Kolb, T. E. and Lavigne, M. B. and Law, B. E. and Margolis, H. A. and Martin, T. and McCaughey, J. H. and Misson, L. and Montes-Helu, M. and Noormets, A. and Randerson, J. T. and Starr, G. and Xiao, J., 2010. Ecosystem carbon dioxide fluxes after disturbance in forests of North America. J. Geophys. Res. G, 115(G00K02): 13.    Am001iw.pdf      

Abstract: Disturbances are important for renewal of North American forests. Here we summarize more than 180 site years of eddy covariance measurements of carbon dioxide flux made at forest chronosequences in North America. The disturbances included standreplacing fire (Alaska, Arizona, Manitoba, and Saskatchewan) and harvest (British Columbia, Florida, New Brunswick, Oregon, Quebec, Saskatchewan, and Wisconsin) events, insect infestations (gypsy moth, forest tent caterpillar, and mountain pine beetle), Hurricane Wilma, and silvicultural thinning (Arizona, California, and New Brunswick). Net ecosystem production (NEP) showed a carbon loss from all ecosystems following a stand?replacing disturbance, becoming a carbon sink by 20 years for all ecosystems and by 10 years for most. Maximum carbon losses following disturbance (g C m?2y?1) ranged from 1270 in Florida to 200 in boreal ecosystems. Similarly, for forests less than 100 years old, maximum uptake (g C m?2y?1) was 1180 in Florida mangroves and 210 in boreal ecosystems. More temperate forests had intermediate fluxes. Boreal ecosystems were relatively time invariant after 20 years, whereas western ecosystems tended to increase in carbon gain over time. This was driven mostly by gross photosynthetic production (GPP) because total ecosystem respiration (ER) and heterotrophic respiration were relatively invariant with age. GPP/ER was as low as 0.2 immediately following stand?replacing disturbance reaching a constant value of 1.2 after 20 years. NEP following insect defoliations and silvicultural thinning showed lesser changes than stand?replacing events, with decreases in the year of disturbance followed by rapid recovery. NEP decreased in a mangrove ecosystem following Hurricane Wilma because of a decrease in GPP and an increase in ER.

An002 Anderson, R. M. and May, R. M., 1980. Infectious diseases and population cycles of forest insects. Science, 210(4470 (Nov.7)): 658-661.    An002.pdf      

Abstract: The regulation of natural populations of invertebrate hosts by viral, bacterial, protozoan, or helminth infections is discussed, using models that combine elements of conventional epidemiology (where the host population is assumed constant) with dynamic elements drawn from predator-prey studies; the apparent absence of acquired immunity in invertebrates simplifies the analysis. Highly pathogenic infections, with long-lived infective stages, tend to produce cyclic behavior in their host populations. The models give an explanation of the 9- to 10-year population cycles of the larch bud moth (Zeiraphera diniana) in the European Alps and suggest that microsporidian protozoan and baculovirus infections may be responsible for the 5- to 12-year population cycles observed in many temperate forest insects.

An254 Anonymous, 2009. Climate change: Looming locusts. Nature, 461(7264): 573-573.    An254.pdf   
An302 Andersen, D. and Cooper, D., 2000. Plant-herbivore-hydroperiod interactions: effects of native mammals on floodplain tree recruitment. Ecol. Appl., 10(5): 1384-1399.    An302.pdf      

Abstract: Floodplain plant-herbivore-hydroperiod interactions have received little attention despite their potential as determinants of floodplain structure and functioning. We used five types of exclosures to differentially exclude small-, medium-, and large-sized mammals from accessing Fremont cottonwood (Populus deltoides Marshall subsp. wizlizenii (Watson) Eckenwalder) seedlings and saplings growing naturally on four landform types at an alluvial reach on each of two rivers, the Green and Yampa, in Colorado and Utah. The two study reaches differed primarily as a result of flow regulation on the Green River, which began in 1962. Landforms were a rarely hooded portion of the alluvial plain, geomorphically active slow- and fast-water channel margin sites on the Yampa reach, and an aggrading side channel on the Green. Small-mammal live-trapping and observational data indicated that, with minor exceptions, the kinds of mammals rating cottonwood within each reach were identical. We monitored condition and fates of individual cottonwood plants from October 1993 through the 1997 growing season. Differences in survival and growth were noted both within and between reaches, and both due to, and independent of, mammalian herbivory. Comparisons of cottonwood growth and survivorship among exclosures and between exclosures and controls indicated that a small mammal, Microtus montanus, reduced seedling and sapling survivorship at the Green River reach, but to a lesser extent (seedlings) or not at all (saplings) on the Yampa reach. In contrast, reductions in sapling height increment attributable to medium- and large-sized herbivores were detected only at the Yampa site. We suggest that these differences are a result of (1) flow regulation allowing Microtus populations to escape the mortality normally accompanying the large, snowmelt-driven spring flood, as well as regulation promoting a herbaceous understory favorable to voles, and (2) greater browsing pressure from overwintering deer and elk at the Yampa reach, unrelated to flow regulation. Within areas used by foraging beaver, the probability of a sapling being cut by beaver was similar on the two reaches. This study suggests that changes in riparian plant-herbivore relationships due to shifts in river hydrology may be a common and important consequence of river regulation.

An303 Andrews, P. and O'Brien, E., 2000. Climate, vegetation, and predictable gradients in mammal species richness in southern Africa. J. Zool., 251: 205-231.    An303.pdf      

Abstract: Many hypotheses have been proposed to account for geographic variations in species diversity. In general these relate to some aspect of climate, particularly climatic variables measuring available or potential energy, but while these relate directly to plant diversity they may only indirectly affect mammal species richness. We have examined these relationships by mapping and correlating mammal species richness in southern Africa (n = 285 species) with 15 climatic variables, two topographic variables, and woody plant species richness (n = 1359 species). The effect of area on richness was held a constant by using an equal-area grid cell matrix superimposed on species range maps, with each grid cell equal to 25 000 km(2). We found that variability in the plant species richness alone accounts for 75\% of the variability in mammal species richness. Of the climatic variables, only thermal seasonality approaches this figure, accounting for 69\% of the variability, while annual measures of temperature, precipitation or energy account for only 14-35\% of variability. Differences from North American mammal diversity studies, where annual temperature, and hence annual potential evapotranspiration (PET), have been found to be more important, are attributed in part to southern Africa's climate and vegetation being largely temperate to tropical, as opposed to temperate to polar in North America. By distinguishing different types of mammal based on size, spatial and dietary guilds, other differences emerge. Strong correlations with annual temperature exist only for large mammals, accounting for 60-67\% of the variability in species richness of large mammals compared with <20\% for small mammals. Small mammals are strongly correlated with other climatic or vegetation parameters, especially plant richness and thermal seasonality; frugivorous and insectivorous mammal richness is correlated with thermal seasonality and minimum monthly PET; and arboreal and aerial species richness is correlated with plant richness, thermal seasonality and minimum monthly PET. Up to 77\% of the variability in richness of arboreal, frugivorous and insectivorous species can be explained by woody plant richness, compared with only 38-48\% of the variability in terrestrial herbivores. It is clear from this that different kinds of mammals are differentially affected by climatic and environmental factors, and this explains some of the discrepancies found in earlier studies where no distinction was made between different sizes or guilds of mammal. This result has implications both for the conservation of mammalian communities at the present time and for understanding the evolution and structure of mammalian communities in the past.

An305 Andersson, M. and Erlinge, S., 1977. Influence of predation on rodent populations. OIKOS, 29(3): 591-597.    An305.pdf   

Abstract: Predation on populations of small rodents is reviewed. Various types of predators are distinguished; specialists, generalists, residents, and "nomadic" species. Their functional and numerical responses to changes in prey density, and their influence on small rodent numbers, are discussed. The shape of the functional response curve of the predators may be important for the dynamics of the predator-prey system. Generalists with access to alternative prey tend to stabilize rodent numbers, as do migrating specialists, whereas resident specialists may be destabilizing. Field studies on cyclic rodent populations point to the importance of predation during and after the decline phase, and indicate that predation may increase the amplitude and prolong the period of the cycles. Other studies indicate a strong influence of predation on rodent numbers in areas with a diversified prey and predator fauna.

As016 Asner, G. P. and Levick, S. R. and Kennedy-Bowdoin, T. and Knapp, D. E. and Emerson, R. and Jacobson, J. and Colgan, M. S. and Martin, R. E., 2009. Large-scale impacts of herbivores on the structural diversity of African savannas. Proc. Natl. Acad. Sci. USA, 106(12): 4947-4952.    As016.pdf      

Abstract: African savannas are undergoing management intensification, and decision makers are increasingly challenged to balance the needs of large herbivore populations with the maintenance of vegetation and ecosystem diversity. Ensuring the sustainability of Africa's natural protected areas requires information on the efficacy of management decisions at large spatial scales, but often neither experimental treatments nor large-scale responses are available for analysis. Using a new airborne remote sensing system, we mapped the three-dimensional (3-D) structure of vegetation at a spatial resolution of 56 cm throughout 1640 ha of savanna after 6-, 22-, 35-, and 41-year exclusions of herbivores, as well as in unprotected areas, across Kruger National Park in South Africa. Areas in which herbivores were excluded over the short term (6 years) contained 38\%-80\% less bare ground compared with those that were exposed to mammalian herbivory. In the longer-term (> 22 years), the 3-D structure of woody vegetation differed significantly between protected and accessible landscapes, with up to 11-fold greater woody canopy cover in the areas without herbivores. Our maps revealed 2 scales of ecosystem response to herbivore consumption, one broadly mediated by geologic substrate and the other mediated by hillslope-scale variation in soil nutrient availability and moisture conditions. Our results are the first to quantitatively illustrate the extent to which herbivores can affect the 3D structural diversity of vegetation across large savanna landscapes.

Au010 Auer, C., 1975. Jährliche und langfristige Dichteveränderungen bei Lärchenwicklerpopulationen (Zeiraphera diniana Gn.) ausserhalb des Optimumgebietes. Mitt. Schweiz. Entomol. Ges., 48: 47-58.
Au085 Aukema, B. H. and Carroll, A. L. and Zheng, Y. and Zhu, J. and Raffa, K. F. and Moore, R. D. and Stahl, K. and Taylor, S. W., 2008. Movement of outbreak populations of mountain pine beetle: influences of spatiotemporal patterns and climate. Ecography, 31(3): 348-358.    Au085.pdf      

Abstract: Insect outbreaks exert landscape-level influences, yet quantifying the relative contributions of various exogenous and endogenous factors that contribute to their pattern and spread remains elusive. We examine an outbreak of mountain pine beetle covering an 800 thousand ha area on the Chilcotin Plateau of British Columbia, Canada, during the 1970s and early 1980s. We present a model that incorporates the spatial and temporal arrangements of outbreaking insect populations, as well as various climatic factors that influence insect development. Onsets of eruptions of mountain pine beetle demonstrated landscape-level synchrony. On average, the presence of outbreaking populations was highly correlated with outbreaking populations within the nearest 18 km the same year and local populations within 6 km in the previous two years. After incorporating these spatial and temporal dependencies, we found that increasing temperatures contributed to explaining outbreak probabilities during this 15 yr outbreak. During collapse years, landscape-level synchrony decpard while local synchrony values remained high, suggesting that in some areas host depletion was contributing to population decpar. Model forecasts of outbreak propensity one year in advance at a 12 by 12 km scale provided 80\% accuracy over the landscape, and never underestimated the occurrence of locally outbreaking populations. This model provides a flexible approach for linking temperature and insect population dynamics to spatial spread, and complements existing decision support tools for resource managers.

Ay001 Ayres, M. P. and Lombardero, M. J., 2000. Assessing the consequences of global change for forest disturbance from herbivores and pathogens. Sci. Total Environ., 262(3): 263-286.    Ay001.pdf      

Abstract: Herbivores and pathogens impact the species composition, ecosystem function, and socioeconomic value of forests. Herbivores and pathogens are an integral part of forests, but sometimes produce undesirable effects and a degradation of forest resources. In the United States, a few species of forest pests routinely have significant impacts on up to 20 million ha of forest with economic costs that probably exceed $1 billion/year. Climatic change could alter patterns of disturbance from herbivores and pathogens through: (1) direct effects on the development and survival of herbivores and pathogens; (2) physiological changes in tree defenses; and (3) indirect effects from changes in the abundance of natural enemies (e.g. parasitoids of insect herbivores), mutualists (e.g. insect vectors of tree pathogens), and competitors. Because of their short life cycles, mobility, reproductive potential, and physiological sensitivity to temperature, even modest climate change will have rapid impacts on the distribution and abundance of many forest insects and pathogens. We identify 32 syndromes of biotic disturbance in North American forests that should be carefully evaluated for their responses to climate change: 15 insect herbivores, browsing mammals; 12 pathogens; 1 plant parasite; and 3 undiagnosed patterns of forest decline. It is probable that climatic effects on some herbivores and pathogens will impact on biodiversity, recreation, property value, forest industry, and even water quality. Some scenarios are beneficial (e.g. decreased snow cover may increase winter mortality of some insect pests), but many are detrimental (e.g. warming tends to accelerate insect development rate and facilitate range expansions of pests and climate change tends to produce a mismatch between mature trees and their environment, which can increase vulnerability to herbivores and pathogens). Changes in forest disturbance can produce feedback to climate through affects on water and carbon flux in forest ecosystems; one alarming scenario is that climate warming may increase insect outbreaks in boreal forests, which would tend to increase forest fires and exacerbate further climate warming by releasing carbon stores from boreal ecosystems. We suggest a list of research priorities that will allow us to refine these risk assessments and adopt forest management strategies that anticipate changes in biotic disturbance regimes and mitigate the ecological, social, and economic risks. (C) 2000 Elsevier Science B.V. All rights reserved.

Ba001iw Baird, N. A. and Etter, P. D. and Atwood, T. S. and Currey, M. C. and Shiver, A. L. and Lewis, Z. A. and Selker, E. U. and Cresko, W. A. and Johnson, E. A., 2008. Rapid SNP discovery and genetic mapping using sequenced RAD markers. PLoS ONE, 3(10): e3376.    Ba001iw.pdf      

Abstract: Single nucleotide polymorphism (SNP) discovery and genotyping are essential to genetic mapping. There remains a need for a simple, inexpensive platform that allows high-density SNP discovery and genotyping in large populations. Here we describe the sequencing of restriction-site associated DNA (RAD) tags, which identified more than 13,000 SNPs, and mapped three traits in two model organisms, using less than half the capacity of one Illumina sequencing run. We demonstrated that different marker densities can be attained by choice of restriction enzyme. Furthermore, we developed a barcoding system for sample multiplexing and fine mapped the genetic basis of lateral plate armor loss in threespine stickleback by identifying recombinant breakpoints in F-2 individuals. Barcoding also facilitated mapping of a second trait, a reduction of pelvic structure, by in silico re-sorting of individuals. To further demonstrate the ease of the RAD sequencing approach we identified polymorphic markers and mapped an induced mutation in Neurospora crassa. Sequencing of RAD markers is an integrated platform for SNP discovery and genotyping. This approach should be widely applicable to genetic mapping in a variety of organisms.

Ba023 Baltensweiler, W. and Benz, G. and Bovey, P. and Delucchi, V., 1977. Dynamics of larch bud moth populations, Zeiraphera diniana (Gn.) (Lepidoptera, Tortricidae). Annu. Rev. Entomol., 22: 79-100.    Ba023.pdf   
Ba033 Baltensweiler, W. and Fischlin, A., 1979. The rôle of migration for the population dynamics of the larch bud moth, Zeiraphera diniana Gn. (Lep. Tortricidae). Mitt. Schweiz. Ent. Ges., 52: 259-271.    Ba033.pdf      

Abstract: Moth flight of Z. diniana (defoliator of larch stands) was monitored during the last population cycle by means of pheromone and light traps in an area of approximately 20,000 km2. The relationship between larval density and male moth catch is quantified by means of the power function y = axb. Long range migration over several 100 km may contribute to the synchronization of outbreaks along the alpine arch, but this stochastic form of migration cannot influence the regularity of the cycles. This regularity appears to stem from regional migration phenomena; i.e., moths immigrate annually by positive anemotactic behavior from lower altitudes into the upper region of alpine mountain valleys. A verbal model of migration is outlined in view of simulation studies in the future.

Ba061 Baltensweiler, W. and Fischlin, A., 1988. The larch bud moth in the Alps. In: Berryman, A. A. (eds.), Dynamics of forest insect populations: patterns, causes, implications. Plenum Publishing Corporation, New York a.o., 331-351pp.    Ba061.pdf      
Ba266 Bachelet, D. and Neilson, R. P. and Hickler, T. and Drapek, R. J. and Lenihan, J. M. and Sykes, M. T. and Smith, B. and Sitch, S. and Thonicke, K., 2003. Simulating past and future dynamics of natural ecosystems in the United States. Global Biogeochem. Cycles, 17(2): 1045.    Ba266.pdf      

Abstract: Simulations of potential vegetation distribution, natural fire frequency, carbon pools, and fluxes are presented for two DGVMs (Dynamic Global Vegetation Models) from the second phase of the Vegetation/Ecosystem Modeling and Analysis Project. Results link vegetation dynamics to biogeochemical cycling for the conterminous United States. Two climate change scenarios were used: a moderately warm scenario from the Hadley Climate Centre and a warmer scenario from the Canadian Climate Center. Both include sulfate aerosols and assume a gradual CO2 increase. Both DGVMs simulate a reduction of southwestern desert areas, a westward expansion of eastern deciduous forests, and the expansion of forests in the western part of the Pacific Northwest and in north-central California. Both DGVMs predict an increase in total biomass burnt in the next century, with a more pronounced increase under the Canadian scenario. Under the Hadley scenario, both DGVMs simulate increases in total carbon stocks. Under the Canadian scenario, both DGVMs simulate a decrease in live vegetation carbon. We identify similarities in model behavior due to the climate forcing and explain differences by the different structure of the models and their different sensitivity to CO2. We compare model output with data to enhance our confidence in their ability to simulate potential vegetation distribution and ecosystem processes. We compare changes in the area of drought-induced decreases in vegetation density with a spatial index derived from the Palmer Drought Severity Index to illustrate the ability of the vegetation to cope with water limitations in the future and the role of the CO2 fertilization effect.

Ba349 Bachelet, D. and Lenihan, J. M. and Daly, C. and Neilson, R. P. and Ojima, D. S. and Parton, W. J., 2001. MC1: a dynamic vegetation model for estimating the distribution of vegetation and associated carbon, nutrients, and water---technical documentation. Version 1.0.. Gen. Tech. Rep..S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Portland, OR, USA, 95pp.    Ba349.pdf   

Abstract: Assessments of vegetation response to climate change have generally been made only by equilibrium vegetation models that predict vegetation composition under steady-state conditions. These models do not simulate either ecosystem biogeochemical processes or changes in ecosystem structure that may, in turn, act as feedbacks in determining the dynamics of vegetation change. MC1 is a new dynamic global vegetation model created to assess potential impacts of global climate change on ecosystem structure and function at a wide range of spatial scales from landscape to global. This new tool allows us to incorporate transient dynamics and make real time predictions about the patterns of ecological change. MC1 was created by combining physiologically based biogeographic rules defined in the MAPSS model with a modified version of the biogeochemical model, CENTURY. MC1 also includes a fire module, MCFIRE, that mechanistically simulates the occurrence and impacts of fire events.

Ba454 Battipaglia, G. and Frank, D. and Buentgen, U. and Dobrovolny, P. and Brazdil, R. and Pfister, C. and Esper, J., 2010. Five centuries of Central European temperature extremes reconstructed from tree-ring density and documentary evidence. Glob. Planet. Chang., 72(3): 182-191.    Ba454_S2.pdf      

Abstract: Future climate change will likely influence the frequency and intensity of weather extremes. As such events are by definition rare, long records are required to understand their characteristics, drivers, and consequences on ecology and society. Herein we provide a unique perspective on regional-scale temperature extremes over the past millennium, using three tree-ring maximum latewood density (MXD) chronologies from higher elevations in the European Alps. We verify the tree-ring-based extremes using documentary evidences from Switzerland, the Czech Republic, and Central Europe that allowed the identification of 44 summer extremes over the 1550-2003 period. These events include cold temperatures in 1579, 1628, 1675, and 1816, as well as warm ones in 1811 and 2003. Prior to 1550, we provide new evidence for cold (e.g., 1068 and 1258) and warm (e.g., 1333) summers derived from the combined MXD records and thus help to characterize high-frequency temperature variability during medieval times. Spatial coherence of the reconstructed extremes is found over Switzerland, with most signatures even extending across Central Europe. We discuss potential limitations of the tree-ring and documentary archives, including the (i) ability of MXD to particularly capture extremely warm temperatures, (ii) methodological identification and relative definition of extremes, and (iii) placement of those events in the millennium-long context of low-frequency climate change. (C) 2010 Elsevier B.V. All rights reserved.

Be002 Benz, G., 1974. Negative Rückkoppelung durch Raum- und Nahrungskonkurrenz sowie zyklische Veränderung der Nahrungsgrundlage als Regelprinzip in der Populationsdynamik des Grauen Lärchenwicklers, Zeiraphera diniana (Guenée) (Lep. Tortricidae). Z. angew. Entomol., 76: 196-228.    Be002.pdf      

Abstract: Negative feed-back by competition for food and space, and by cyclic induced changes in the nutritional base as regulatory principles in the population dynamics of the larch budmoth Zeiraphera diniana (Guenée). At high density of the larvae of Z. diniana on larch trees in subalpine forests, intraspecific competition causes an increase in mortality of larvae and pupae, as well as reduction of pupal weight and fecundity of the emerging moths. The negative effects become more pronounced by shortage of food at population levels leading to complete defoliation of the larch trees. Defoliation in turn activates specific mechanisms in the trees, which lead to late and slow sprouting of the needles in spring (weak coincidence), short needles (reduced mass of nutritional base), and reduced quality of the needles (elevated contents of fibres and reduced protein contents). Thus the succeeding bud moth populations are depressed by negative feed-back. The cyclic numeric fluctuations with a periodicity of 8 to 10 years, which are characteristic of populations of Z. diniana in its optimum area, may thus be regarded as the expression of an autoregulating life system in which the species multiplies for 4--5 generations under favorable conditions and thus, transgressing the carrying capacity, changes the nutritional base in such a way that environmental resistance to the species becomes high for another 4 generations.

Be076 Berryman, A. A., 1996. What causes population cycles of forest Lepidoptera?. Trends Ecol. Evol., 11(1): 28-32.    Be076.pdf   

Abstract: Hypotheses for the causes of regular cycles in populations of forest Lepidoptera have invoked pathogen-insect or foliage-insect interactions. However, the available data suggest that forest caterpillar cycles are more likely to be the result of interactions with insect parasitoids, an old argument that seems to have been neglected in recent years.

Be130 Berryman, A. and Turchin, P., 1997. Detection of delayed density dependence: Comment. Ecology, 78(1): 318-320.    Be130.pdf      
Be211 Berg, E. E. and Henry, J. D. and Fastie, C. L. and De Volder, A. D. and Matsuoka, S. M., 2006. Spruce beetle outbreaks on the Kenai Peninsula, Alaska, and Kluane National Park and Reserve, Yukon Territory: Relationship to summer temperatures and regional differences in disturbance regimes. For. Ecol. Manage., 227(3): 219-232.    Be211.pdf      

Abstract: When spruce beetles (Dendroctonus rufipennis) thin a forest canopy, surviving trees grow more rapidly for decades until the canopy closes and growth is suppressed through competition. We used measurements of tree rings to detect such growth releases and reconstruct the history of spruce beetle outbreaks at 23 mature spruce (Picea spp.) forests on and near the Kenai Peninsula, Alaska and four mature white spruce (Picea glauca) forests in Kluane National Park and Reserve, Yukon Territory. On the Kenai Peninsula, all stands showed evidence of 1-5 thinning events with thinning occurring across several stands during the 1810s, 1850s, 1870-1880s, 1910s, and 1970-1980s, which we interpreted as regional spruce beetle outbreaks. However, in the Kluane region we only found evidence of substantial thinning in one stand from 1934 to 1942 and thinning was only detected across stands during this same time period. Over the last 250 years, spruce beetle outbreaks therefore occurred commonly among spruce forests on the Kenai Peninsula, at a mean return interval of 52 years, and rarely among spruce forests in the Kluane region where cold winter temperatures and fire appear to more strongly regulate spruce beetle population size. The massive 1990s outbreaks witnessed in both regions appeared to be related to extremely high summer temperatures. Recent outbreaks on the Kenai Peninsula (1971-1996) were positively associated with the 5-year backwards running average of summer temperature. We suggest that warm temperature influences spruce beetle population size through a combination of increased overwinter survival, a doubling of the maturation rate from 2 years to I year, and regional drought-induced stress of mature host trees. However, this relationship decoupled after 1996, presumably because spruce beetles had killed most of the susceptible mature spruce in the region. Thus sufficient numbers of mature spruce are needed in order for warm summer temperatures to trigger outbreaks on a regional scale. Following the sequential and large outbreaks of the 1850s, 1870-1880s, and 1910s, spruce beetle outbreaks did not occur widely again until the 1970s. This suggests that it may take decades before spruce forests on the Kenai Peninsula mature following the 1990s outbreak and again become susceptible to another large spruce beetle outbreak. However, if the recent warming trend continues, endemic levels of spruce beetles will likely be high enough to perennially thin the forests as soon as the trees reach susceptible size. (c) 2006 Elsevier B.V. All rights reserved.

Be293 Bentz, B. J. and Regniere, J. and Fettig, C. J. and Hansen, E. M. and Hayes, J. L. and Hicke, J. A. and Kelsey, R. G. and Negron, J. F. and Seybold, S. J., 2010. Climate Change and Bark Beetles of the Western United States and Canada: Direct and Indirect Effects. Bioscience, 60(8): 602-613.    Be293.pdf      

Abstract: Climatic changes are predicted to significantly affect the frequency and severity of disturbances that shape forest ecosystems. We provide a synthesis of climate change effects on native bark beetles, important mortality agents of conifers in western North America. Because of differences in temperature-dependent life-history strategies, including cold-induced mortality and developmental timing, responses to warming will differ among and within bark beetle species. The success of bark beetle populations will also be influenced indirectly by the effects of climate on community associates and host-tree vigor, although little information is available to quantify these relationships. We used available population models and climate forecasts to explore the responses of two eruptive bark beetle species. Based on projected warming, increases in thermal regimes conducive to population success are predicted for Dendroctonus rufipennis (Kirby) and Dendroctonus ponderosae Hopkins, although there is considerable spatial and temporal variability. These predictions from population models suggest a movement of temperature suitability to higher latitudes and elevations and identify regions with a high potential for bark beetle outbreaks and associated tree mortality in the coming century.

Be294 Berggren, A. and Bjorkman, C. and Bylund, H. and Ayres, M. P., 2009. The distribution and abundance of animal populations in a climate of uncertainty. OIKOS, 118(8): 1121-1126.    Be294.pdf      

Abstract: Current predictions regarding the ecological consequences of climate change on animal populations are generally autecological and species-specific, and/or non-mechanistic extrapolations of recent short-term patterns. To better understand and predict the effects of climate change on the distribution of species and the abundance of populations we offer a novel, broad theoretical framework. Climate-induced changes in trophic structure may actually be more predictable than effects on individual species. The logic is that there are general differences in climatic sensitivity among trophic levels - specifically, that as one moves up trophic levels, there is an increase in the temperature sensitivity of vital rates. More precisely, we provide: (1) a formal mathematical definition of distribution limits that is both operational and conceptual, introducing the concept DL50, defined as the geographic and climatic isopar representing an equilibrium occupancy of half of the suitable habitats; (2) a matrix of the possible changes in trophic structure from climate change and the general theoretical consequences; and (3) a new idea that predicts broad effects of climatic warming on trophic systems. Our intention is to help meet the challenge of developing and testing general theoretical models that can predict which species will be winners and losers in ecological time, which evolutionary traits will be favoured or selected against, and what will be consequences for ecosystem structure and function.

Be296 Berryman, A., 1991. Stabilization or regulation - what it all means. Oecologia, 86(1): 140-143.    Be296.pdf      

Bi077 Bigler, C. and Veblen, T. T., 2011. Changes in litter and dead wood loads following tree death beneath subalpine conifer species in northern Colorado. Can. J. For. Res., 41(2): 331-340.    Bi077.pdf      

Abstract: Litter and dead wood affect important processes in forest ecosystems such as nutrient and carbon cycling and are key influences on biodiversity and fire behavior. Increased tree mortality rates in western North America associated with climate trends and increased bark beetle activity highlight the need to better understand the dynamics of litter and dead wood following tree death. For eight old-growth stands in a subalpine forest landscape in northern Colorado (USA), we compared litter and dead wood loads beneath more than 200 dead and live Engelmann spruce (Picea engelmannii Parry ex Engelm.), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), and lodgepole pine (Pinus contorta Douglas ex Loudon). The dynamics of litter and dead wood were analyzed using chronosequences of tree death dates over >100 years that we determined from tree rings. Immediately following tree death, high loads of litter accumulated, particularly for the biggest spruces, which accumulated 10 times more litter than live spruces (five times more for fir, two times more for pine). We estimated a higher decay rate of litter for spruce (half-life of four years) than for pine (15 years) and fir (19 years). The accumulation rates for dead wood following tree death were highly variable among trees, but maximum accumulation was attained during the first 50-60 years.

Bi078 Bigler, C. and Gavin, D. G. and Gunning, C. and Veblen, T. T., 2007. Drought induces lagged tree mortality in a subalpine forest in the Rocky Mountains. OIKOS, 116(12): 1983-1994.    Bi078.pdf      

Abstract: Extreme climatic events are key factors in initiating gradual or sudden changes in forest ecosystems through the promotion of severe, tree-killing disturbances such as fire, blowdown, and widespread insect outbreaks. In contrast to these climatically-incited disturbances, little is known about the more direct effect of drought on tree mortality, especially in high-elevation forests. Therefore projections of drought-induced mortality under future climatic conditions remain uncertain. For a subalpine forest landscape in the Rocky Mountains of northern Colorado (USA), we quantified lag effects of drought on mortality of Engelmann spruce Picea engelmannii, subalpine fir Abies lasiocarpa, and lodgepole pine Pinus contorta. For the period 1910-2004, we related death dates of 164 crossdated dead trees to early-season and late-season droughts. Following early-season droughts, spruce mortality increased over five years and fir mortality increased sharply over 11 years. Following late-season droughts, spruce showed a small increase in mortality within one year, whereas fir showed a consistent period of increased mortality over two years. Pine mortality was not affected by drought. Low pre-drought radial growth rates predisposed spruce and fir to drought-related mortality. Spruce and fir trees that died during a recent drought (2000-2004) had significantly lower pre-drought growth rates than live neighbour trees. Overall, we found large interspecific differences in drought-related mortality with fir showing the strongest effect followed by spruce and pine. This direct influence of climatic variability on differential tree mortality has the potential for driving large-scale changes in subalpine forests of the Rocky Mountains.

Bj002 Bjornstad, O. N. and Peltonen, M. and Liebhold, A. M. and Baltensweiler, W., 2002. Waves of larch budmoth outbreaks in the European Alps. Science, 298(5595): 1020-1023.    Bj002.pdf    Bj002_S.pdf      

Abstract: Spatially extended population models predict complex spatiotemporal patterns, such as spiral waves and spatial chaos, as a result of the reaction-diffusion dynamics that arise from trophic interactions. However, examples of such patterns in ecological systems are scarce. We develop a quantitative technique to demonstrate the existence of waves in Central European larch budmoth (Zeiraphera diniana Gn.) outbreaks. We show that these waves travel toward the northeast-east at 210 kilometers per year. A theoretical model involving a moth-enemy interaction predicts directional waves, but only if dispersal is directionally biased or habitat productivity varies across the landscape. Our study confirms that nonlinear ecological interactions can lead to complex spatial dynamics at a regional scale.

Bl084 Blais, J. R. and Roberts, B. A. and Chow, T. L. and Syme, P. D. and Royama, T. and Stranks, D. W., 1977. Stand treatments and spruce budworm damages. Bimonthly Res. Notes, 33(6 (Nov.,Dec.)): 42-43.    Bl084.pdf      
Bl088 Blaum, N. and Mosner, E. and Schwager, M. and Jeltsch, F., 2011. How functional is functional? Ecological groupings in terrestrial animal ecology: towards an animal functional type approach. Biodivers. Conserv., 20(11): 2333-2345.    Bl088.pdf      

Abstract: Understanding mechanisms to predict changes in plant and animal communities is a key challenge in ecology. The need to transfer knowledge gained from single species to a more generalized approach has led to the development of categorization systems where species' similarities in life strategies and traits are classified into ecological groups (EGs) like functional groups/types or guilds. While approaches in plant ecology undergo a steady improvement and refinement of methodologies, progression in animal ecology is lagging behind. With this review, we aim to initiate a further development of functional classification systems in animal ecology, comparable to recent developments in plant ecology. We here (i) give an overview of terms and definitions of EGs in animal ecology, (ii) discuss existing classification systems, methods and application areas of EGs (focusing on terrestrial vertebrates), and (iii) provide a ``roadmap towards an animal functional type approach'' for improving the application of EGs and classifications in animal ecology. We found that an animal functional type approach requires: (i) the identification of core traits describing species' dependency on their habitat and life history traits, (ii) an optimization of trait selection by clustering traits into hierarchies, (iii) the assessment of ``soft traits'' as substitute for hardly measurable traits, e.g. body size for dispersal ability, and (iv) testing of deparated groups for validation including experiments.

Bo121 Bond, W. J. and Midgley, G. F. and Woodward, F. I., 2003. What controls South African vegetation - climate or fire?. South Afr. J. Bot., 69(1): 79-91.    Bo121.pdf   

Abstract: The role of fire in determining biome distribution in South Africa has long been debated. Acocks labelled veld types that he thought were 'fire climax' as 'false'. He hypothesised that their current extent was due to extensive forest clearance by Iron Age farmers. We tested the relative importance of fire and climate in determining ecosystem characteristics by simulating potential vegetation of South Africa with and without fire using a Dynamic Global Vegetation Model (DGVM). The simulations suggest that most of the eastern half of the country could support much higher stem biomass without fire and that the vegetation would be dominated by trees instead of grasses. Fynbos regions in mesic winter rainfall areas would also become tree dominated. We collated results of long term fire exclusion studies to further test the relative importance of fire and climate. These show that grassy ecosystems with rainfall >650mm tend towards fire-sensitive forests with fire excluded. Areas below 650mm showed changes in tree density and size but no trend of changing composition to forest. We discuss recent evidence that C-4 grasslands first appeared between 6 and 8M years BP, long before the appearance of modern humans. However these grassy ecosystems are among the most recently developed biomes on the planet. We briefly discuss the importance of fire in promoting their spread in the late Tertiary.

Bo122 Bond, W. J. and Midgley, G. F. and Woodward, F. I., 2003. The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas. Global Change Biol., 9(7): 973-982.    Bo122.pdf      

Abstract: The distribution and abundance of trees can be strongly affected by disturbance such as fire. In mixed tree/grass ecosystems, recurrent grass-fuelled fires can strongly suppress tree saplings and therefore control tree dominance. We propose that changes in atmospheric [CO2] could influence tree cover in such metastable ecosystems by altering their postburn recovery rates relative to flammable herbaceous growth forms such as grasses. Slow sapling recovery rates at low [CO2] would favour the spread of grasses and a reduction of tree cover. To test the possible importance of [CO2]/fire interactions, we first used a Dynamic Global Vegetation Model (DGVM) to simulate biomass in grassy ecosystems in South Africa with and without fire. The results indicate that fire has a major effect under higher rainfall conditions suggesting an important role for fire/[CO2] interactions. We then used a demographic model of the effects of fire on mesic savanna trees to test the importance of grass/tree differences in postburn recovery rates. We adjusted grass and tree growth in the model according to the DGVM output of net primary production at different [CO2] relative to current conditions. The simulations predicted elimination of trees at [CO2] typical of the last glacial period (180 ppm) because tree growth rate is too slow (15 years) to grow to a fire-proof size of ca. 3 m. Simulated grass growth would produce an adequate fuel load for a burn in only 2 years. Simulations of preindustrial [CO2] (270 ppm) predict occurrence of trees but at low densities. The greatest increase in trees occurs from preindustrial to current [CO2] (360 ppm). The simulations are consistent with palaeo-records which indicate that trees disappeared from sites that are currently savannas in South Africa in the last glacial. Savanna trees reappeared in the Holocene. There has also been a large increase in trees over the last 50-100 years. We suggest that slow tree recovery after fire, rather than differential photosynthetic efficiencies in C-3 and C-4 plants, might have been the significant factor in the Late Tertiary spread of flammable grasslands under low [CO2] because open, high light environments would have been a prerequisite for the spread of C-4 grasses. Our simulations suggest further that low [CO2] could have been a significant factor in the reduction of trees during glacial times, because of their slower regrowth after disturbance, with fire favouring the spread of grasses.

Bo145 Bond, W. J. and Woodward, F. I. and Midgley, G. F., 2005. The global distribution of ecosystems in a world without fire. New Phytol., 165(2): 525-537.    Bo145.pdf      

Abstract: This paper is the first global study of the extent to which fire determines global vegetation patterns by preventing ecosystems from achieving the potential height, biomass and dominant functional types expected under the ambient climate (climate potential). To determine climate potential, we simulated vegetation without fire using a dynamic global-vegetation model. Model results were tested against fire exclusion studies from different parts of the world. Simulated dominant growth forms and tree cover were compared with satellite-derived land- and tree-cover maps. Simulations were generally consistent with results of fire exclusion studies in southern Africa and elsewhere. Comparison of global 'fire off' simulations with landcover and treecover maps show that vast areas of humid C-4 grasslands and savannas, especially in South America and Africa, have the climate potential to form forests. These are the most frequently burnt ecosystems in the world. Without fire, closed forests would double from 27% to 56% of vegetated grid cells, mostly at the expense of C-4 plants but also of C-3 shrubs and grasses in cooler climates. C-4 grasses began spreading 6-8 Ma, long before human influence on fire regimes. Our results suggest that fire was a major factor in their spread into forested regions, splitting biotas into fire tolerant and intolerant taxa.

Bo147 Bonan, G. B. and Levis, S. and Sitch, S. and Vertenstein, M. and Oleson, K. W., 2003. A dynamic global vegetation model for use with climate models: concepts and description of simulated vegetation dynamics. Global Change Biol., 9(11): 1543-1566.    Bo147.pdf      

Abstract: Changes in vegetation structure and biogeography due to climate change feedback to alter climate by changing fluxes of energy, moisture, and momentum between land and atmosphere. While the current class of land process models used with climate models parameterizes these fluxes in detail, these models prescribe surface vegetation and leaf area from data sets. In this paper, we describe an approach in which ecological concepts from a global vegetation dynamics model are added to the land component of a climate model to grow plants interactively. The vegetation dynamics model is the Lund-Potsdam-Jena (LPJ) dynamic global vegetation model. The land model is the National Center for Atmospheric Research (NCAR) Land Surface Model (LSM). Vegetation is defined in terms of plant functional types. Each plant functional type is represented by an individual plant with the average biomass, crown area, height, and stem diameter (trees only) of its population, by the number of individuals in the population, and by the fractional cover in the grid cell. Three time-scales (minutes, days, and years) govern the processes. Energy fluxes, the hydrologic cycle, and carbon assimilation, core processes in LSM, occur at a 20 min time step. Instantaneous net assimilated carbon is accumulated annually to update vegetation once a year. This is carried out with the addition of establishment, resource competition, growth, mortality, and fire parameterizations from LPJ. The leaf area index is updated daily based on prevailing environmental conditions, but the maximum value depends on the annual vegetation dynamics. The coupling approach is successful. The model simulates global biogeography, net primary production, and dynamics of tundra, boreal forest, northern hardwood forest, tropical rainforest, and savanna ecosystems, which are consistent with observations. This suggests that the model can be used with a climate model to study biogeophysical feedbacks in the climate system related to vegetation dynamics.

Bo164 Bondeau, A. and Smith, P. and Zähle, S. and Schaphoff, S. and Lucht, W. and Cramer, W. and Gerten, D. and Lotze-Campen, H. and Müller, C. and Reichstein, M. and Smith, B., 2007. Modelling the role of agriculture for the 20th century global terrestrial carbon balance. Global Change Biol., 13(3): 679-706.    Bo164.pdf   

Abstract: In order to better assess the role of agriculture within the global climate-vegetation system, we present a model of the managed planetary land surface, Lund-Potsdam-Jena managed Land (LPJmL), which simulates biophysical and biogeochemical processes as well as productivity and yield of the most important crops worldwide, using a concept of crop functional types (CFTs). Based on the LPJ-Dynamic Global Vegetation Model, LPJmL simulates the transient changes in carbon and water cycles due to land use, the specific phenology and seasonal CO2 fluxes of agricultural-dominated areas, and the production of crops and grazing land. It uses 13 CFTs (11 arable crops and two managed grass types), with specific parameterizations of phenology connected to leaf area development. Carbon is allocated daily towards four carbon pools, one being the yield-bearing storage organs. Management (irrigation, treatment of residues, intercropping) can be considered in order to capture their effect on productivity, on soil organic carbon and on carbon extracted from the ecosystem. For transient simulations for the 20th century, a global historical land use data set was developed, providing the annual cover fraction of the 13 CFTs, rain-fed and/or irrigated, within 0.5 degrees grid cells for the period 1901-2000, using published data on land use, crop distributions and irrigated areas. Several key results are compared with observations. The simulated spatial distribution of sowing dates for temperate cereals is comparable with the reported crop calendars. The simulated seasonal canopy development agrees better with satellite observations when actual cropland distribution is taken into account. Simulated yields for temperate cereals and maize compare well with FAO statistics. Monthly carbon fluxes measured at three agricultural sites also compare well with simulations. Global simulations indicate a similar to 24% (respectively similar to 10%) reduction in global vegetation (respectively soil) carbon due to agriculture, and 6-9 Pg C of yearly harvested biomass in the 1990s. In contrast to simulations of the potential natural vegetation showing the land biosphere to be an increasing carbon sink during the 20th century, LPJmL simulates a net carbon source until the 1970s (due to land use), and a small sink (mostly due to changing climate and CO2) after 1970. This is comparable with earlier LPJ simulations using a more simple land use scheme, and within the uncertainty range of estimates in the 1980s and 1990s. The fluxes attributed to land use change compare well with Houghton's estimates on the land use related fluxes until the 1970s, but then they begin to diverge, probably due to the different rates of deforestation considered. The simulated impacts of agriculture on the global water cycle for the 1990s are similar to 5% (respectively similar to 20%) reduction in transpiration (respectively interception), and similar to 44% increase in evaporation. Global runoff, which includes a simple irrigation scheme, is practically not affected.

Bo248 Bond, W. J., 2008. What limits trees in C-4 grasslands and savannas?. Annu. Rev. Ecol. Evol. Syst., 39: 641-659.    Bo248.pdf      

Abstract: Though the distribution of global vegetation can generally be predicted from climate, grasslands are an exception. C-4 grassy biomes cover vast areas that are warm enough and wet enough to support closed forests. The extent of this climate mismatch has been revealed by physiologically based global vegetation simulations and by large empirical data sets. Reasons for the existence of grassy biomes have long been debated, polarized into bottom-up (resources) or top-down (fire,herbivory) arguments. Recent studies indicate that both are important, especially in suppressing woody recruits. Grasses are formidable competitors below ground, create highly flammable fuels, and can support large herbivore densities. The net effect on trees is rare and episodic recruitment of adults in tree-fall gaps. The implication is that ecosystem structure and function depend on demographic transitions. Tree cover is increasing and grass/forest boundaries are changing. These changes can have large feedbacks to the earth-atmosphere system. Though progress has been made, there is still great uncertainty in predicting the future of C-4 grassy biomes.

Bo249 Bolin, B. and Sukumar, R. and Ciais, P. and Cramer, W. and Jarvis, P. and Kheshgi, H. and Nobre, C. and Semenov, S. and Steffen, W., 2000. Global perspective. In: Watson, R. T. and Noble, I. R. and Bolin, B. and Ravindranath, N. H. and Verardo, D. J. and Dokken, D. J. (eds.), Land use, land-use change, and forestry - A special report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge, 377pp.   
Bo252 Bonan, G. and Levis, S. and Kergoat, L. and Oleson, K., 2002. Landscapes as patches of plant functional types: An integrating concept for climate and ecosystem models. Glob. Biogeochem. Cycles, 16(2): 1021.    Bo252.pdf      

Abstract: [1] While most land models developed for use with climate models represent vegetation as discrete biomes, this is, at least for mixed life-form biomes, inconsistent with the leaf-level and whole-plant physiological parameterizations needed to couple these biogeophysical models with biogeochemical and ecosystem dynamics models. In this paper, we present simulations with the National Center for Atmospheric Research land surface model (NCAR LSM) that examined the effect of representing vegetation as patches of plant functional types (PFTs) that coexist within a model grid cell. This approach is consistent with ecological theory and models and allows for unified treatment of vegetation in climate and ecosystem models. In the standard NCAR LSM the PFT composition and leaf area for each grid cell are obtained by classifying grid cells as 1 of 28 possible biomes. Here, we develop a data set from 1-km satellite data that provides each model grid cell a unique PFT composition and leaf area for each PFT. Global simulations at 3degrees x 3degrees spatial resolution showed that ground temperature, ground evaporation, and northern high-latitude winter albedo exhibited direct responses to these landscape changes, which led to indirect effects such as in soil moisture and sensible and latent heat fluxes. Additional simulations at 2degrees x 2degrees and 1degrees x 1degrees spatial resolution showed that low-resolution simulations masked landscape heterogeneity in both approaches but the satellite-based, continuous representation of vegetation reduced model sensitivity to resolution. It is argued that the use of spatially continuous distributions of coexisting PFTs is a necessary step to link climate and ecosystem models.

Bo253 Boulanger, Y. and Arseneault, D., 2004. Spruce budworm outbreaks in eastern Quebec over the last 450 years. Can. J. Forest Res., 34(5): 1035-1043.    Bo253.pdf      

Abstract: In this study we used dendrochronology to reconstruct the history of eastern spruce budworm (Choristoneura fumiferana (Clem.)) outbreaks over the last 450 years in the Bas-Saint-Laurent region of southeastern Quebec. In total, 260 tree cores were sampled from 204 beams in seven historic buildings and 12 trees in a virgin forest stand. Eight previously documented outbreaks (1975-1992, 1947-1958, 1914-1923, 1868-1882, 1832-1845, 1805-1812, 1752-1776, 1710-1724) and three presumed previous outbreaks (1678-1690, 1642-1648, 1577-1600) were identified based on periods of growth reduction. Of these 11 confirmed or presumed outbreaks, six were documented for the first time in eastern Quebec. Such data suggest that outbreak frequency has remained quite stable, with a mean interval of about 40 years between the midpoint of successive outbreaks since the mid-16th century. In addition, together with previous studies, our results indicate a strong spatial synchrony of spruce budworm outbreaks across central and eastern Quebec during the last 300 years. Consequently, our study does not support the hypothesis that spruce budworm outbreak frequency and synchrony increased during the 20th century.

Br219 Brovkin, V. and Raddatz, T. and Reick, C. H. and Claussen, M. and Gayler, V., 2009. Global biogeophysical interactions between forest and climate. Geophys. Res. Lett., 36: L07405.    Br219.pdf      

Abstract: In two sensitivity experiments using the Earth System Model of the Max Planck Institute for Meteorology (MPIESM), the vegetation cover of the ice-free land surface has been set worldwide to either forest or grassland in order to quantify the quasi-equilibrium response of the atmosphere and ocean components to extreme land surface boundary conditions. After 400 years of model integration, the global mean annual surface temperature increased by 0.7 degrees K and decpard by 0.6 degrees K in the forest and grassland simulations, respectively, as compared to the control simulation. Thereafter, the geographic distribution of vegetation has been allowed to respond interactively to climate. After subsequent 500 years of interactive climate-vegetation dynamics, both forest and grassland simulations converged to essentially the same climate state as in the control simulation. This convergence suggests an absence of multiple climate-forest states in the current version of the MPI-ESM. Citation: Brovkin, V., T. Raddatz, C. H. Reick, M. Claussen, and V. Gayler (2009), Global biogeophysical interactions between forest and climate, Geophys. Res. Lett., 36, L07405, doi:10.1029/2009GL037543.

Br220 Bryant, J. and Swihart, R. and Reichardt, P. and Newton, L., 1994. Biogeography of woody plant-chemical defense against snowshoe hare browsing - comparison of Alaska and eastern North-America. OIKOS, 70(3): 385-395.    Br220.pdf      

Abstract: Recent research has demonstrated that juvenile-stage woody plants from Alaska and eastern Siberia (Beringia) are more defended against browsing by hares (Lepus) in winter than the juvenile-stage of congeners from other subarctic regions. Our objectives were (1) to determine if similar biogeographical variation in woody plant defense occurs in subarctic North America, and (2) to evaluate some possible causes of this variation. To achieve these objectives we (1) conducted feeding trials that compared snowshoe hare (L. americanus) preferences for winter-dormant twigs of juvenile-stage tree birch and aspen from Alaska with hare preferences for the juvenile-stage of congeners and conspecifics from eastern North America (Maine and Connecticut), and (2) in the case of birch related hare preferences to twig defensive chemistry. We found that hares preferred eastern North American plants, and preferences for birch were related to defensive chemistry. Two historical explanations for such biogeographical variation in the chemical defense of juvenile-stage subarctic woody plants against browsing by hares have been suggested by Bryant et al.: (1) It is a consequence of geographic variation in the intensity of browsing by Pleistocene megaherbivores; or (2) it is a consequence of very large-scale spatial variation in intensity of browsing by hares and associated extant fire-adapted mammals. Using the glacial history and fire history of subarctic North America, we developed scenarios that allowed us to evaluate these historical hypotheses. We also considered the possibility that biogeographical variation in defense of subarctic woody plants against browsing by mammals is a result of ecological responses of plants to the physical environment. While fully recognizing that all three processes may have contributed to the biogeographical pattern in plant defense we documented, we have concluded that browsing by hares and other extant fire-adapted mammals is likely to be the most important cause. This conclusion indicates that the climatic variation that developed across subarctic North America after the ice age has resulted in a geographical pattern in North American wildfire history, which through effects on vegetation has influenced the intensity of selective browsing by mammals in winter and thereby resulted in biogeographical variation in the chemical defense of woody plants against browsing.

Br221 Brovkin, V. and Ganopolski, A. and Svirezhev, Y., 1997. A continuous climate-vegetation classification for use in climate-biosphere studies. Ecol. Model., 101(2-3): 251-261.    Br221.pdf      

Abstract: An interactive coupling of global climate models with models for the terrestrial vegetation requires a reduction of the number of vegetation classes in comparison with traditional bioclimatic classification. We suggest a continuous vegetation classification based on two main plant functional types: trees and grass. Correspondence between climate and these vegetation types on a global scale was analysed on the basis of stare-of-the-art global climate and vegetation datasets. An empirical formula describing a fraction of trees as a function of climate (mean annual temperature and precipitation) was obtained. (C) 1997 Elsevier Science B.V.

Br224 Brook, B. W. and Bradshaw, C. J. A., 2006. Strength of evidence for density dependence in abundance time series of 1198 species. Ecology, 87(6): 1445-1451.    Br224.pdf      

Abstract: Population limitation is a fundamental tenet of ecology, but the relative roles of exogenous and endogenous mechanisms remain unquantified for most species. Here we used multi-model inference (MMI), a form of model averaging, based on information theory (Akaike's Information Criterion) to evaluate the relative strength of evidence for density-dependent and density-independent population dynamical models in long-term abundance time series of 1198 species. We also compared the MMI results to more classic methods for detecting density dependence: Neyman-Pearson hypothesis-testing and best-model selection using the Bayesian Information Criterion or cross-validation. Using MMI on our large database, we show that density dependence is a pervasive feature of population dynamics (median MMI support for density dependence = 74.7-92.2\%), and that this holds across widely different taxa. The weight of evidence for density dependence varied among species but increased consistently with the number of generations monitored. Best-model selection methods yielded similar results to MMI (a density-dependent model was favored in 66.2-93.9\% of species time series), while the hypothesis-testing methods detected density dependence less frequently (32.6-49.8\%). There were no obvious differences in the prevalence of density dependence across major taxonomic groups under any of the statistical methods used. These results underscore the value of using multiple modes of analysis to quantify the relative empirical support for a set of working hypotheses that encompass a range of realistic population dynamical behaviors.

Br226 Bret-Harte, M. S. and MacK, M. C. and Goldsmith, G. R. and Sloan, D. B. and Demarco, J. and Shaver, G. R. and Ray, P. M. and Biesinger, Z. and Chapin, F. S. and III, 2008. Plant functional types do not predict biomass responses to removal and fertilization in Alaskan tussock tundra. J. Ecol., 96(4): 713-726.    Br226.pdf      

Abstract: 1. Plant communities in natural ecosystems are changing and species are being lost due to anthropogenic impacts including global warming and increasing nitrogen (N) deposition. We removed dominant species, combinations of species and entire functional types from Alaskan tussock tundra, in the presence and absence of fertilization, to examine the effects of non-random species loss on plant interactions and ecosystem functioning. 2. After 6 years, growth of remaining species had compensated for biomass loss due to removal in all treatments except the combined removal of moss, Betula nana and Ledum palustre (MBL), which removed the most biomass. Total vascular plant production returned to control levels in all removal treatments, including MBL. Inorganic soil nutrient availability, as indexed by resins, returned to control levels in all unfertilized removal treatments, except MBL. 3. Although biomass compensation occurred, the species that provided most of the compensating biomass in any given treatment were not from the same functional type (growth form) as the removed species. This provides empirical evidence that functional types based on effect traits are not the same as functional types based on response to perturbation. Calculations based on redistributing N from the removed species to the remaining species suggested that dominant species from other functional types contributed most of the compensatory biomass. 4. Fertilization did not increase total plant community biomass, because increases in graminoid and deciduous shrub biomass were offset by decreases in evergreen shrub, moss and lichen biomass. Fertilization greatly increased inorganic soil nutrient availability. 5. In fertilized removal treatments, deciduous shrubs and graminoids grew more than expected based on their performance in the fertilized intact community, while evergreen shrubs, mosses and lichens all grew less than expected. Deciduous shrubs performed better than graminoids when B. nana was present, but not when it had been removed. 6. Synthesis. Terrestrial ecosystem response to warmer temperatures and greater nutrient availability in the Arctic may result in vegetative stable-states dominated by either deciduous shrubs or graminoids. The current relative abundance of these dominant growth forms may serve as a predictor for future vegetation composition.

Bu171 Büntgen, U. and Frank, D. and Liebhold, A. and Johnson, D. and Carrer, M. and Urbinati, C. and Grabner, M. and Nicolussi, K. and Levani, T. and Esper, J., 2009. Three centuries of insect outbreaks across the European Alps. New Phytologist, 2009(182): 929-941.    Bu171.pdf      

Abstract: * Knowledge of the persistence of regular larch budmoth outbreaks is limited in space and time. Although dendrochronological methods have been used to reconstruct insect outbreaks, their presence may be obscured by climatic influences. * More than 5000 tree-ring series from 70 larch host and 73 spruce nonhost sites within the European Alps and Tatra Mountains were compiled. Site-specific assessment of growth--climate responses and the application of six larch budmoth detection methods considering host, nonhost and instrumental time-series revealed spatiotemporal patterns of insect defoliation across the Alpine arc. * Annual maps of reconstructed defoliation showed historical persistence of cyclic outbreaks at the site level, recurring c. every 8--9 yr. Larch budmoth outbreaks occurred independently of rising temperatures from the Little Ice Age until recent warmth. Although no collapse in outbreak periodicity was recorded at the local scale, synchronized Alpine-wide defoliation has ceased during recent decades. * Our study demonstrates the persistence of recurring insect outbreaks during AD 1700--2000 and emphasizes that a widely distributed tree-ring network and novel analysis methods can contribute towards an understanding of the changes in outbreak amplitude, synchrony and climate dependence.

Bu250 Büntgen, U. and Tegel, W. and Nicolussi, K. and McCormick, M. and Frank, D. and Trouet, V. and Kaplan, J. O. and Herzig, F. and Heussner, K.-U. and Wanner, H. and Luterbacher, J. and Esper, J., 2011. 2500 years of european climate variability and human susceptibility. Science, 331(6017): 578-582.    Bu250.pdf    Bu250_S.pdf    Bu250_S2.pdf      

Abstract: Climate variations have influenced the agricultural productivity, health risk, and conflict level of preindustrial societies. Discrimination between environmental and anthropogenic impacts on past civilizations, however, remains difficult because of the paucity of high-resolution palaeoclimatic evidence. Here, we present tree ring–based reconstructions of Central European summer precipitation and temperature variability over the past 2500 years. Recent warming is unprecedented, but modern hydroclimatic variations may have at times been exceeded in magnitude and duration. Wet and warm summers occurred during periods of Roman and medieval prosperity. Increased climate variability from ~AD 250 to 600 coincided with the demise of the Western Roman Empire and the turmoil of the Migration Period. Historical circumstances may challenge recent political and fiscal reluctance to mitigate projected climate change.

Bu252 Buentgen, U. and Frank, D. and Wilson, R. and Carrer, M. and Urbinati, C., 2008. Testing for tree-ring divergence in the European Alps. Glob. Chang. Biol., 14(10): 2443-2453.      

Abstract: Evidence for reduced sensitivity of tree growth to temperature has been reported from multiple forests along the high northern latitudes. This alleged circumpolar phenomenon described the apparent inability of temperature-sensitive tree-ring width and density chronologies to parallel increasing instrumental temperature measurements since the mid-20th century. In addition to such low-frequency trend offset, the inability of formerly temperature-sensitive tree growth to reflect high-frequency temperature signals in a warming world is indicated at some boreal sites, mainly in Alaska, the Yukon and Siberia. Here, we refer to both of these findings as the 'divergence problem' (DP), with their causes and scale being debated. If DP is widespread and the result of climatic forcing, the overall reliability of tree-ring-based temperature reconstructions should be questioned. Testing for DP benefits from well-replicated tree-ring and instrumental data spanning from the 19th to the 21st century. Here, we present a network of 124 larch and spruce sites across the European Alpine arc. Tree-ring width chronologies from 40 larch and 24 spruce sites were selected based on their correlation with early (1864-1933) instrumental temperatures to assess their ability of tracking recent (1934-2003) temperature variations. After the tree-ring series of both species were detrended in a manner that allows low-frequency variations to be preserved and scaled against summer temperatures, no unusual late 20th century DP is found. Independent tree-ring width and density evidence for unprecedented late 20th century temperatures with respect to the past millennium further reinforces our results.

Ca107 Carroll, A. L. and Taylor, S. W. and Régnière, J. and Safranyik, L., 2004. Effects of climate change on range expansion by the mountain pine beetle in British Columbia. In: Shore, T. L. and Brooks, J. E. and Stone, J. E. (eds.), Mountain Pine Beetle Symposium: Challenges and Solutions. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Report, Victoria, British Columbia, Information, 223-232pp.    Ca107.pdf   

Abstract: The current latitudinal and elevational range of mountain pine beetle is not limited by available hosts. Instead, its potential to expand north and east has been restricted by climatic conditions unfavorable for brood development. We combined a model of the impact of climatic conditions on the establishment and persistence of mountain pine beetle populations with a spatially explicit, climate-driven simulation tool. Historic weather records were used to produce maps of the distribution of past climatically suitable habitats for mountain pine beetles in British Columbia. Overlays of annual mountain pine beetle occurrence on these maps were used to determine if the beetle has expanded its range in recent years due to changing climate. An examination of the distribution of climatically suitable habitats in 10- year increments derived from climate normals (1921-1950 to 1971-2000) clearly shows an increase in the range of benign habitats. Furthermore, an increase (at an increasing rate) in the number of infestations since 1970 in formerly climatically unsuitable habitats indicates that mountain pine beetle populations have expanded into these new areas. Given the rapid colonization by mountain pine beetles of former climatically unsuitable areas during the last several decades, continued warming in western North America associated with climate change will allow the beetle to further expand its range northward, eastward and toward higher elevations.

Ca149 Canadell, J. G. and Pataki, D. E. and Gifford, R. and Houghton, R. A. and Luo, Y. and Raupach, M. R. and Smith, P. and Steffen, W., 2007. Saturation of the terrestrial carbon sink. In: Canadell, J. G. and Pataki, D. E. and Pitelka, L. F. (eds.), Terrestrial ecosystems in a changing world. Springer-Verlag, Berlin, 59-78pp.    Ca149.pdf      
Ca155 Candau, J. N. and Fleming, R. A., 2005. Landscape-scale spatial distribution of spruce budworm defoliation in relation to bioclimatic conditions. Can. J. For. Res., 35(9): 2218-2232.    Ca155.pdf      

Abstract: Two empirical statistical models were developed to describe the spatial variation in defoliation by spruce budworm (Choristoneura fumiferana Clem.), as recorded by Ontario's Forest Health Survey from 1967 to 1998. These models revealed a number of relationships between the spatial distributions of aerially detectable spruce budworm defoliation and bioclimatic conditions over the landscape. A classification tree model relates the northern and southern boundaries of defoliation to the relative abundance of different tree species that host spruce budworm. Between these boundaries, the classification tree uses the maximum winter temperature and the minimum temperature in May to describe where detectable defoliation occurred. A regression tree model uses a total of eight variables related to winter temperatures, forest composition, spring temperatures, summer temperatures, and precipitation to estimate the defoliation frequency in areas where defoliation was detected at least once from 1967 to 1998. High defoliation frequencies were associated with dry Junes (precipitation, < 86 mm) and cool springs (mean minimum temperature < -2.7 degrees C). Conversely, low frequencies were associated with cold winters (mean minimum temperature < -23.3 degrees C; mean maximum temperature > -11.0 degrees C) in the north and a low abundance of host species (percentage of the basal area occupied by balsam fir, white spruce, and black spruce, < 14.3%) in the south. Spatial autocorrelation in the bioclimatic variables had little effect on their relationships with the spatial distribution of the defoliation frequency.

Ca156 Candau, J. N. and Fleming, R. A. and Hopkin, A., 1998. Spatiotemporal patterns of large-scale defoliation caused by the spruce budworm in Ontario since 1941. Can. J. For. Res., 28(11): 1733-1741.    Ca156.pdf      

Abstract: Survey records of spruce budworm (Choristneura fumiferana Clem.) defoliation in Ontario, taken annually since 1941, were analysed using geographic information systems (GIS), spatial statistics, and time-series methods. Cumulative frequency maps indicated that the 41 x 10(6) ha of Ontario that had been defoliated in at least one year since 1941 could be sprit into three zones of frequent defoliation separated by two approximately 100 km wide, longitudinally oriented corridors of lower frequency. Analysis of annual records of the total area defoliated showed that the fluctuations in this time series are the result of a basic oscillation of approximately 36 years, which is modified by secondary fluctuations and occasionally by sharp drops. The secondary fluctuations are at least partially due to asynchrony in otherwise remarkably similar long-wave oscillations in the eastern (25.5 x 10(6) ha) and western (9.6 x 10(6) ha) zones of frequent defoliation. Analysis of this asynchrony showed that outbreaks in the eastern zone occurred 5 or 6 years before outbreaks in the central (6.6 x 10(6) ha) and western zones, which were synchronous. These observations contradict previous reports of the large-scale spread of outbreaks from west to east.

Ce035 Cech, P. G. and Venterink, H. O. and Edwards, P. J., 2010. N and P cycling in Tanzanian humid savanna: influence of herbivores, fire, and N-2-fixation. Ecosystems, 13(7): 1079-1096.    Ce035.pdf      

Abstract: Availabilities of nitrogen (N) and phosphorus (P) have a strong influence on plant growth and the species composition of savannas, but it is not clear how these availabilities depend on factors such as fire, N-2-fixation, and activities of wild herbivores and cattle. We quantified soil N and P availabilities in various ways (extractable pools, mineralization, resin adsorption) along vegetation gradients within a recently abandoned cattle ranch and a former game reserve in Tanzania (both areas now part of the Saadani National Park). We also assessed annual N and P balances to evaluate how long-term availabilities of N and P are affected by large herbivores, symbiotic N-2-fixation, and fire. The results show that cattle ranching led to a spatial re-distribution of nutrients, with the local accumulation of P being stronger and more persistent than that of N. In the former game reserve, intensively grazed patches of short grass tended to have elevated soil N and P availabilities; however, because quantities of nutrients removed through grazing exceeded returns in dung and urine, the nutrient balances of these patches were negative. In dense Acacia stands, N-2-fixation increased N availability and caused a net annual N input. Fire was the major cause for nutrient losses from tallgrass savanna, and estimated N inputs from the atmosphere and symbiotic N-2-fixation were insufficient to compensate for these losses. Our results call into question the common assumption that N budgets in annually burned savanna are balanced; rather, these ecosystems are a mosaic of patches with both N enrichment and impoverishment, which vary according to the vegetation type.

Ce036 Cech, P. G. and Kuster, T. and Edwards, P. J. and Venterink, H. O., 2008. Effects of herbivory, fire and N-2-fixation on nutrient limitation in a humid African savanna. Ecosystems, 11(6): 991-1004.    Ce036.pdf      

Abstract: The quantities and spatial distribution of nutrients in savanna ecosystems are affected by many factors, of which fire, herbivory and symbiotic N-2-fixation are particularly important. We measured soil nitrogen (N) pools and the relative abundance of N and phosphorus (P) in herbaceous vegetation in five vegetation types in a humid savanna in Tanzania. We also performed a factorial fertilization experiment to investigate which nutrients most limit herbaceous production. N pools in the top 10 cm of soil were low at sites where fires were frequent, and higher in areas with woody legume encroachment, or high herbivore excretion. Biomass production was co-limited by N and P at sites that were frequently burnt or heavily grazed by native herbivores. In contrast, aboveground production was limited by N in areas receiving large amounts of excreta from livestock. N-2-fixation by woody legumes did not lead to P-limitation, but did increase the availability of N relative to P. We conclude that the effects of fire, herbivory and N-2-fixation upon soil N pools and N:P-stoichiometry in savanna ecosystems are, to a large extent, predictable.

Cl137 Clark, K. L. and Skowronski, N. and Hom, J., 2010. Invasive insects impact forest carbon dynamics. Glob. Chang. Biol., 16(1): 88-101.    Cl137.pdf      

Abstract: Invasive insects can impact ecosystem functioning by altering carbon, nutrient, and hydrologic cycles. In this study, we used eddy covariance to measure net CO2 exchange with the atmosphere (NEE), and biometric measurements to characterize net ecosystem productivity (NEP) in oak-and pine-dominated forests that were defoliated by Gypsy moth (Lymantria dispar L.) in the New Jersey Pine Barrens. Three years of data were used to compare C dynamics; 2005 with minimal defoliation, 2006 with partial defoliation of the canopy and understory in a mixed stand, and 2007 with complete defoliation of an oak-dominated stand, and partial defoliation of the mixed and pine-dominated stands. Previous to defoliation in 2005, annual net CO2 exchange (NEEyr) was estimated at -187, -137 and -204 g C m(-2) yr(-1) at the oak-, mixed-, and pine-dominated stands, respectively. Annual NEP estimated from biometric measurements was 108\%, 100\%, and 98\% of NEEyr in 2005 for the oak-, mixed-, and pine-dominated stands, respectively. Gypsy moth defoliation strongly reduced fluxes in 2006 and 2007 compared with 2005; NEEyr was -122, +103, and -161 g C m(-2) yr(-1) in 2006, and +293, +129, and -17 g C m(-2) yr(-1) in 2007 at the oak-, mixed-, and pine-dominated stands, respectively. At the landscape scale, Gypsy moths defoliated 20.2\% of upland forests in 2007. We calculated that defoliation in these upland forests reduced NEEyr by 41\%, with a 55\% reduction in the heavily impacted oak-dominated stands. 'Transient' disturbances such as insect defoliation, nonstand replacing wildfires, and prescribed burns are major factors controlling NEE across this landscape, and when integrated over time, may explain much of the patterning of aboveground biomass and forest floor mass in these upland forests.

Co182 Cooke, B. J. and Nealis, V. G. and Règnière, J., 2007. Insect defoliators as periodic disturbances in northern forest ecosystems. In: Johnson, E. A. and Miyanishi, K. (eds.), Plant Disturbance Ecology. Academic Press, Burlington, 487-525pp.    Co182.pdf      

Abstract: Recurrent outbreaks of forest insect populations have been discussed extensively in the ecological literature (Myers, 1988; Berryman, 1996), but rarely from the perspective of disturbance ecology. The reason lies, in part, in the traditional focus of quantitative animal ecologists on the species of interest (e.g., Morris, 1959) contrasted with the traditional emphasis of plant ecologists on whole communities (e.g., Tilman, 1982). Further, historical research on forest insects has been motivated largely by the practical problem of insect pest management. While yielding a rich legacy of information on the biology and ecology of a few selected insects, the modeling literature that utilizes this information has generally tended to view disturbance as an economic disruption to be predicted and prevented (Berryman, 1991) rather than as an ecosystem process to be emulated. Emulation of natural disturbances, an approach to ecologically sustainable forest management (Bergeron and Harvey, 1997; Perera et al., 2004), has rekindled interest in insect disturbance modeling. The challenge is how to bring the rich insect population dynamics literature to bear on the subject of disturbance in forest dynamics.

Co188 Colyvan, M. and Ginzburg, L., 2003. The galilean turn in population ecology. Biol. & philosophy, 18(3): 401-414.    Co188.pdf      

Abstract: The standard mathematical models in population ecology assume that a population's growth rate is a function of its environment. In this paper we investigate an alternative proposal according to which the rate of change of the growth rate is a function of the environment and of environmental change. We focus on the philosophical issues involved in such a fundamental shift in theoretical assumptions, as well as on the explanations the two theories offer for some of the key data such as cyclic populations. We also discuss the relationship between this move in population ecology and a similar move from first-order to second-order differential equations championed by Galileo and Newton in celestial mechanics.

Co190 Collinson, M. and Hooker, J., 1991. Fossil evidence of interactions between plants and plant-eating mammals. Philos. Trans. R. Soc. B, 333(1267): 197-208.    Co190.pdf      

Abstract: We document changes in mammalian dietary and foraging locomotor adaptation, and appearances and developments of angiosperm fruiting strategies and vegetation types since the late Cretaceous in the Euramerican region, and to some extent in low latitude Africa. These changes suggest: (i) an expansion in the exploitation of dry fruits and seeds by mammals on the ground as well as in the trees after the terminal Cretaceous dinosaur extinction; (ii) a relation between large nuts and rodents, which appear in the late Palaeocene and radiate in the late Eocene; (iii) a relation between primates and fleshy fruits established in the early-Middle Eocene when tropical forests reached their maximum latitudinal extent; (iv) a hiatus of several million years in the vertebrate exploitation of leaves after dinosaur extinction and before the first few mammalian herbivores in the Middle Palaeocene, followed by an expansion in the late Eocene when climates cooled and more open vegetation became established.

Cr080 Crawley, M., 1989. Insect herbivores and plant-population dynamics. Annu. Rev. Entomol., 34: 531-564.    Cr080.pdf      

Cu026 Cudmore, T. J. and Bjorklund, N. and Carroll, A. L. and Lindgren, B. S., 2010. Climate change and range expansion of an aggressive bark beetle: evidence of higher beetle reproduction in naive host tree populations. J. Appl. Ecol., 47(5): 1036-1043.    Cu026.pdf      

Abstract: P>1. Hosts may evolve defences that make them less susceptible and suitable to herbivores impacting their fitness. Due to climate change-driven range expansion, herbivores are encountering naive host populations with increasing frequency. 2. Aggressive bark beetles are among the most important agents of disturbance in coniferous forest ecosystems. The presence of bark beetle outbreaks in areas with a historically unsuitable climate, in part a consequence of climate change, provided an opportunity to assess the hypothesis that the mountain pine beetle Dendroctonus ponderosae has higher reproductive success in lodgepole pine Pinus contorta trees growing in areas that have not previously experienced frequent outbreaks. 3. We felled and sampled mountain pine beetle-killed trees from historically climatically suitable and unsuitable areas, i.e. areas with and without a historical probability of frequent outbreaks. Reproductive success was determined from a total of 166 trees from 14 stands. 4. Brood productivity was significantly affected by climatic suitability class, such that mean brood production per female increased as historical climatic suitability decreased. 5. Synthesis and applications. The current study demonstrates that the mountain pine beetle has higher reproductive success in areas where its host trees have not experienced frequent beetle epidemics, which includes much of the current outbreak area in north central British Columbia. This increased productivity of mountain pine beetle is likely to have been a key reason for the rapid population buildup that resulted in unprecedented host tree mortality over huge areas in western Canada. The outbreak thus provides an example of how climate change-driven range expansion of native forest insects can have potentially disastrous consequences. Since an increased reproductive success is likely to accelerate the progression of outbreaks, it is particularly critical to manage forests for the maintenance of a mosaic of species and age classes at the landscape level in areas where host tree populations are naive to eruptive herbivores.

Da032 Daniel, C. J. and Myers, J. H., 1995. Climate and outbreaks of the forest tent caterpillar. Ecography, 18(4): 353-362.    Da032.pdf      

Abstract: Some have suggested that the periodic outbreaks of the forest tent caterpillar, Malacosoma disstria are triggered by weather: the temperature at the time of early larval feeding, and overwintering temperatures. To assess the role of these factors, defoliation maps, compiled annually from flight surveys for the province of Ontario, were compared to similarly scaled temperature records. An analysis of the year to year variation shows no relationship between the pattern of increases or declines in defoliation and either temperatures during early larval development, or overwintering temperatures. Four periods of defoliation by forest tent caterpillars were observed in Ontario over 41 yr, but at individual sites extensive defoliation did not occur for each of the outbreak periods. Defoliation was less severe in regions with low overwintering temperatures, but was not related to the average number of de ree days in the early spring. Outbreaks were most common in areas where deciduous forests were extensive, and the mean overwintering temperatures were above -40 degrees C. While these weather variables do not apparently explain the details of population dynamics of forest tent caterpillars, extreme weather conditions might synchronize populations.

Da048 Dale, V. H. and Joyce, L. A. and McNulty, S. and Neilson, R. P. and Ayres, M. P. and Flannigan, M. D. and Hanson, P. J. and Irland, L. C. and Lugo, A. E. and Peterson, C. J. and Simberloff, D. and Swanson, F. J. and Stocks, B. J. and Wotton, B. M., 2001. Climate change and forest disturbances. Bioscience, 51(9): 723-734.    Da048.pdf      

Abstract: Climate change can affect forests by altering the frequency, intensity, duration, and timing of fire, drought, introduced species, insect and pathogen outbreaks, hurricanes, windstorms, ice storms, or landslides

Da071 Daly, C. and Bachelet, D. and Lenihan, J. M. and Neilson, R. P. and Parton, W. and Ojima, D., 2000. Dynamic simulation of tree-grass interactions for global change studies. Ecol. Appl., 10(2): 449-469.    Da071.pdf      

Abstract: The objective of this study was to simulate dynamically the response of a complex landscape, containing forests, savannas, and grasslands, to potential climate change. Thus, it was essential to simulate accurately the competition for light and water between trees and grasses. Accurate representation of water competition requires simulating the appropriate vertical root distribution and soil water content. The importance of different rooting depths in structuring savannas has long been debated. In simulating this complex landscape, we examined alternative hypotheses of tree and grass vertical root distribution and the importance of fire as a disturbance, as they influence savanna dynamics under historical and changing climates. MCl, a new dynamic vegetation model, was used to estimate the distribution of vegetation and associated carbon and nutrient fluxes for Wind Cave National Park, South Dakota, USA. MCl consists of three linked modules simulating biogeography, biogeochemistry, and fire disturbance. This new tool allows us to document how changes in rooting patterns may affect production, fire frequency, and whether or not current vegetation types and life-form mixtures can be sustained at the same location or would be replaced by others. Because climate change may intensify resource deficiencies, it will probably affect allocation of resources to roots and their distribution through the soil profile. We manipulated the rooting depth of two life-forms, trees and grasses, that are competing for water. We then assessed the importance of variable rooting depth on ecosystem processes and vegetation distribution by running MCl for historical climate (1895-1994) and a GCM-simulated future scenario (1995-2094). Deeply rooted trees caused higher tree productivity, lower grass productivity, and longer fire return intervals. When trees were shallowly rooted, grass productivity exceeded that of trees even if total grass biomass was only one-third to one-fourth that of trees. Deeply rooted grasses developed extensive root systems that increased N uptake and, the input of litter into soil organic matter pools. Shallowly rooted grasses produced smaller soil carbon pools. Under the climate change scenario, NPP and live biomass increased for grasses and decreased for trees, and total soil organic matter decreased. Changes in the size of biogeochemical pools produced by the climate change scenario were overwhelmed by the range of responses across the four rooting configurations. Deeply rooted grasses grew larger than shallowly rooted ones, and deeply rooted trees outcompeted grasses for resources. In both historical and future scenarios, fire was required for the coexistence of trees and grasses when deep soil water was available to trees. Consistent changes in fire frequency and intensity were simulated during the climate change scenario: more fires occurred because higher temperatures resulted in decreased fuel moisture. Fire also increased in the deeply rooted grass configurations because grass biomass, which serves as a fine fuel source, was relatively high.

Da120 Day, K. R. and Ayres, M. P. and Harrington, R. and Kidd, N. A. C., 2010. Interannual dynamics of aerial and arboreal green spruce aphid populations. Popul. Ecol., 52(2): 317-327.    Da120.pdf      

Abstract: Partial defoliation of spruce by the green spruce aphid Elatobium abietinum (Walker) is a recurrent event in European and, increasingly, North American forests. The patterns of insect abundance on trees have never been satisfactorily described by a numerical model despite considerable knowledge of endogenous and exogenous factors in the population dynamics of the species. Long-term field population estimates of the aphid on foliage provided the opportunity to evaluate such a model. Unlike comparable models for tree-dwelling aphids, this was also applicable to almost completely independent aphid field data derived from the Rothamsted Insect Survey's nationwide network of suction traps. Although based on relatively few parameters, the model was robust in its predictions of alate aphids geographically remote from the forest in which the original population was estimated. The population maximum, which causes the greatest forest damage, is reached in early summer and can be predicted from knowledge of winter temperature (chill bouts), spring temperature (thermal sum), and interannual negative feedback (density dependence). The model provides confirmation that alate populations of spruce aphids, upon which a number of other extensive studies have been based, are ultimately influenced by similar endogenous and climatic factors and that they are a reasonable proxy for aphids on trees.

Da128 Daux, V. and Edouard, J. L. and Masson-Delmotte, V. and Stievenard, M. and Hoffmann, G. and Pierre, M. and Mestre, O. and Danis, P. A. and Guibal, F., 2011. Can climate variations be inferred from tree-ring parameters and stable isotopes from Larix decidua? Juvenile effects, budmoth outbreaks, and divergence issue. Earth Planet. Sci. Lett., 309(3-4): 221-233.    Da128.pdf      

Abstract: Larch wood has been used for centuries as a building material. Hence, the study of the tree-ring width, the latewood maximal density, and the oxygen and carbon isotope composition of the cellulose of this tree provides potential and valuable insights when reconstructing past climate variability. We explore the qualities and limitations of these proxies, focusing on a forest standing the Névache valley (French Alps). The analysis of 15 trees demonstrates a small intra-tree variability in comparison with the inter-tree variability of ∂13C and ∂18O, and shows that 6 trees, at least, must be pooled to make a population-representative sample. Our results show no juvenile effect for ∂13C. Unlike tree-ring width and density, ∂13C and ∂18O are not altered by budmouth outbreaks. These two parameters therefore appear well suited for climate reconstructions, and depict a strong correlation with July--August temperature and relative humidity. The ∂18O of larch cellulose is also strongly linked with the previous winter (December--March) oxygen isotopic composition of the precipitation. This is consistent with a winter water recharge of soil and ground. The past variations of July--August maximum temperature and relative humidity were established using two different combinations of the isotopic ratios. Uncertainties on the reconstructions are estimated respectively at $\pm$1.4$\,^\circ$C and 3.6%. Inter-annual variations of temperature and relative humidity are well reproduced. However, the reconstructed July--August temperature series diverges from the instrumental one, being lower, after ca. 1990. The effects of the variation through time of the depth of source water and of the ecophysiological response of trees to rising CO2 on the isotope composition are discussed as possible causes of divergence. This `divergence problem' strongly questions the possibility of producing appropriate isotope-based temperature calibration.The relationships between isotopes and the July--August relative humidity are more stationary than those with temperature. This may reflect the first order control of the relative humidity on ∂13C via the stomatal conductance and its influence on the evaporative enrichment of the oxygen of the leaf-water. Our study suggests that past variations of relative humidity in the French Alps can be accurately estimated using the stable isotope composition of larch cellulose.

Da129 Davin, E. and Stöckli, R. and Jaeger, E. and Levis, S. and Seneviratne, S., 2011. COSMO-CLM2: a new version of the COSMO-CLM model coupled to the Community Land Model: a new version of the COSMO-CLM model coupled to the Community Land Model. Clim. Dyn., 37: 1889-1907.    Da129.pdf   

Abstract: This study presents an evaluation of a new biosphere-atmosphere Regional Climate Model. COSMO-CLM 2 results from the coupling between the non-hydrostatic atmospheric model COSMO-CLM version 4.0 and the Community Land Model version 3.5 (CLM3.5). In this coupling, CLM3.5 replaces a simpler land surface parameterization (TERRA_ML) used in the standard COSMO-CLM. Compared to TERRA_ML, CLM3.5 comprises a more complete representation of land surface processes including hydrology, biogeophysics, biogeochemistry and vegetation dynamics. Historical climate simulations over Europe with COSMO-CLM and with the new COSMO-CLM 2 are evaluated against various data products. The simulated climate is found to be substantially affected by the coupling with CLM3.5, particularly in summer. Radiation fluxes as well as turbulent fluxes at the surface are found to be more realistically represented in COSMO-CLM 2 . This subsequently leads to improvements of several aspects of the simulated climate (cloud cover, surface temperature and precipitation). We show that a better partitioning of turbulent fluxes is the central factor allowing for the better performances of COSMO-CLM 2 over COSMO-CLM. Despite these improvements, some model deficiencies still remain, most notably a substantial underestimation of surface net shortwave radiation. Overall, these results highlight the importance of land surface processes in shaping the European climate and the benefit of using an advanced land surface model for regional climate simulations.

De148 Denman, K. L. and Brasseur, G. and Chidthaisong, A. and Ciais, P. and Cox, P. M. and Dickinson, R. E. and Hauglustaine, D. and Heinze, C. and Holland, E. and Jacob, D. and Lohmann, U. and Ramachandran, S. and da Silva Dias, P. L. and Wofsy, S. C. and Zhang, X., 2007. Couplings between changes in the climate system and biogeochemistry. In: Solomon, S. and Qin, D. and Manning, M. and Chen, Z. and Marquis, M. and Averyt, K. B. and Tignor, M. and Miller, H. L. (eds.), Climate change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge, UK and New York, NY, USA, 499-587pp.    De148.pdf   
De213 Desantis, L. R. G. and Feranec, R. S. and MacFadden, B. J., 2009. Effects of global warming on ancient mammalian communities and their environments. PLoS ONE, 4(6): e5750.    De213.pdf      

Abstract: Background: Current global warming affects the composition and dynamics of mammalian communities and can increase extinction risk; however, long-term effects of warming on mammals are less understood. Dietary reconstructions inferred from stable isotopes of fossil herbivorous mammalian tooth enamel document environmental and climatic changes in ancient ecosystems, including C-3/C-4 transitions and relative seasonality. Methodology/Principal Findings: Here, we use stable carbon and oxygen isotopes preserved in fossil teeth to document the magnitude of mammalian dietary shifts and ancient floral change during geologically documented glacial and interglacial periods during the Pliocene (similar to 1.9 million years ago) and Pleistocene (similar to 1.3 million years ago) in Florida. Stable isotope data demonstrate increased aridity, increased C-4 grass consumption, inter-faunal dietary partitioning, increased isotopic niche breadth of mixed feeders, niche partitioning of phylogenetically similar taxa, and differences in relative seasonality with warming. Conclusion/Significance: Our data show that global warming resulted in dramatic vegetation and dietary changes even at lower latitudes (similar to 28 degrees N). Our results also question the use of models that predict the long term decpar and extinction of species based on the assumption that niches are conserved over time. These findings have immediate relevance to clarifying possible biotic responses to current global warming in modern ecosystems.

Do076 Dobrovolny, P. and Moberg, A. and Brazdil, R. and Pfister, C. and Glaser, R. and Wilson, R. and van Engelen, A. and Limanowka, D. and Kiss, A. and Halickova, M. and MacKova, J. and Riemann, D. and Luterbacher, J. and Boehm, R., 2010. Monthly, seasonal and annual temperature reconstructions for Central Europe derived from documentary evidence and instrumental records since AD 1500. Clim. Chang., 101(1-2): 69-107.    Do076.pdf    Do076_S.pdf    Do076_S2.pdf      

Abstract: Monthly temperature series for Central Europe back to AD 1500 are developed from documentary index series from Germany, Switzerland and the Czech Republic (1500-1854) and 11 instrumental temperature records (1760-2007). Documentary evidence from the Low Countries, the Carpathian Basin and Poland are used for cross-checking for earlier centuries. The instrumental station records are corrected for inhomogeneities, including insufficient radiation protection of early thermometers and the urban heat island effect. For overlapping period (1760-1854), the documentary data series correlate with instrumental temperatures, most strongly in winter (86\% explained variance in January) and least in autumn (56\% in September). For annual average temperatures, 81\% of the variance is explained. Verification statistics indicate high reconstruction skill for most months and seasons. The last 20 years (since 1988) stand out as very likely the warmest 20-year period, accounting for the calibration uncertainty and decreases in proxy data quality before the calibration period. The new reconstruction displays a previously unobserved long-term decrease in DJF, MAM and JJA temperature variability over last five centuries. Compiled monthly, seasonal and annual series can be used to improve the robustness of gridded large-scale European temperature reconstructions and possible impact studies. Further improvement of the reconstruction would be achieved if documentary data from other European countries are further developed.

Do078 Doherty, S. J. and Bojinski, S. and Henderson-Sellers, A. and Noone, K. and Goodrich, D. and Bindoff, N. L. and Church, J. A. and Hibbard, K. A. and Karl, T. R. and Kajefez-Bogataj, L. and Lynch, A. H. and Parker, D. E. and Prentice, I. C. and Ramaswamy, V. and Saunders, R. W. and Smith, M. S. and Steffen, K. and Stocker, T. F. and Thorne, P. W. and Trenberth, K. E. and Verstraete, M. M. and Zwiers, F. W., 2009. Lessons learned from IPCC AR4 scientific developments needed to understand, predict, and respond to climate change. Bull. Am. Meteorol. Soc., 90(4): 497-+.    Do078.pdf      

Abstract: The Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) concluded that global warming is ``unequivocal'' and that most of the observed increase since the mid-twentieth century is very likely due to the increase in anthropogenic greenhouse gas concentrations, with discernible human influences on ocean warming, continental-average temperatures, temperature extremes, wind patterns, and other physical and biological indicators, impacting both socioeconomic and ecological systems. It is now clear that we are committed to some level of global climate change, and it is imperative that this be considered when planning future climate research and observational strategies. The Global Climate Observing System program (GCOS), the World Climate Research Programme (WCRP), and the International Geosphere-Biosphere Programme (IGBP) therefore initiated a process to summarize the lessons learned through AR4 Working Groups I and II and to identify a set of high-priority modeling and observational needs. Two classes of recommendations emerged. First is the need to improve climate models, observational and climate monitoring systems, and our understanding of key processes. Second, the framework for climate research and observations must be extended to document impacts and to guide adaptation and mitigation efforts. Research and observational strategies specifically aimed at improving our ability to predict and understand impacts, adaptive capacity, and societal and ecosystem vulnerabilities will serve both purposes and are the subject of the specific recommendations made in this paper.

Du060 Dukes, J. S. and Pontius, J. and Orwig, D. and Garnas, J. R. and Rodgers, V. L. and Brazee, N. and Cooke, B. and Theoharides, K. A. and Stange, E. E. and Harrington, R. and Ehrenfeld, J. and Gurevitch, J. and Lerdau, M. and Stinson, K. and Wick, R. and Ayres, M., 2009. Responses of insect pests, pathogens, and invasive plant species to climate change in the forests of northeastern North America: What can we predict?. Can. J. Forest Res., 39(2): 231-248.    Du060.pdf    Du060_S.pdf      

Abstract: Climate models project that by 2100, the northeastern US and eastern Canada will warm by approximately 3-5 degrees C, with increased winter precipitation. These changes will affect trees directly and also indirectly through effects on ``nuisance'' species, such as insect pests, pathogens, and invasive plants. We review how basic ecological principles can be used to predict nuisance species' responses to climate change and how this is likely to impact northeastern forests. We then examine in detail the potential responses of two pest species (hemlock woolly adelgid (Adelges tsugae Annand) and forest tent caterpillar (Malacosoma disstria Hubner), two pathogens (armillaria root rot (Armillaria spp.) and beech bark disease (Cryptococcus fagisuga Lind. + Neonectria spp.), and two invasive plant species (glossy buckthorn (Frangula alnus Mill.) and oriental bittersweet (Celastrus orbiculatus Thunb.) Several of these species are likely to have stronger or more widespread effects on forest composition and structure under the projected climate. However, uncertainty pervades our predictions because we lack adequate data on the species and because some species depend on complex, incompletely understood, unstable relationships. While targeted research will increase our confidence in making predictions, some uncertainty will always persist. Therefore, we encourage policies that allow for this uncertainty by considering a wide range of possible scenarios.

Dy001iw Dymond, C. C. and Neilson, E. T. and Stinson, G. and Porter, K. and MacLean, D. A. and Gray, D. R. and Campagna, M. and Kurz, W. A., 2010. Future spruce budworm outbreak may create a carbon source in eastern Canadian forests. Ecosystems, 13: 917-931.    Dy001iw.pdf   

Abstract: Spruce budworm (Choristoneura fumiferana Clem.) is an important and recurrent disturbance throughout spruce (Picea sp.) and balsam fir (Abies balsamea L.) dominated forests of North America. Forest carbon (C) dynamics in these ecosystems are affected during insect outbreaks because millions of square kilometers of forest suffer growth loss and mortality. We tested the hypothesis that a spruce budworm outbreak similar to those in the past could switch a forest froma C sink to a source in the near future.We used a model of ecosystem C to integrate past spruce budworm impact sequences with current forest management data on 106,000 km2 of forest in eastern Que´bec. Spruce budworm-causedmortality decreased stand-level merchantable C stocks by 11--90% and decreased ecosystem C stocks by 2--10% by the end of the simulation. For the first 13 years (2011--2024), adding spruce budworm significantly reduced ecosystem C stock change for the landscape from a sink (4.6 $\pm$ 2.7 g C m-2 y-1 in 2018) to a source (-16.8 $\pm$ 3.0 g C m-2 y-1 in 2018). This result was mostly due to reduced net primary production. The ecosystem stock change was reduced on average by 2 Tg C y-1 for the entire simulated area. This study provides the first estimate that spruce budworm can significantly affect the C sink or source status of a large landscape. These results indicate that reducing spruce budworm impacts on timber may also provide an opportunity to mitigate a C source.

Es012 Esper, J. and Büntgen, U. and Frank, D. C. and Nievergelt, D. and Liebhold, A., 2007. 1200 years of regular outbreaks in alpine insects. Proc. R. Soc. Lond. Ser. B Biol. Sci., 274(1610): 671-679.    Es012.pdf      

Abstract: The long-term history of Zeiraphera diniana Gn. (the larch budmoth, LBM) outbreaks was reconstructed from tree rings of host subalpine larch in the European Alps. This record was derived from 47 513 maximum latewood density measurements, and highlights the impact of contemporary climate change on ecological disturbance regimes. With over 1000 generations represented, this is the longest annually resolved record of herbivore population dynamics, and our analysis demonstrates that remarkably regular LBM fluctuations persisted over the past 1173 years with population peaks averaging every 9.3 years. These regular abundance oscillations recurred until 1981, with the absence of peak events during recent decades. Comparison with an annually resolved, millennium-long temperature reconstruction representative for the European Alps (r=0.72, correlation with instrumental data) demonstrates that regular insect population cycles continued despite major climatic changes related to warming during medieval times and cooling during the Little Ice Age. The late twentieth century absence of LBM outbreaks, however, corresponds to a period of regional warmth that is exceptional with respect to the last 1000+ years, suggesting vulnerability of an otherwise stable ecological system in a warming environment.

Es016 Esper, J. and Niederer, R. and Bebi, P. and Frank, D., 2008. Climate signal age effects - Evidence from young and old trees in the Swiss Engadin. For. Ecol. Manage., 255(11): 3783-3789.    Es016.pdf      

Abstract: A potential limitation of tree-ring based climate reconstructions is related to climate signal age effects (CSAE). CSAE may arise if the climatic response of young tree-rings differs from that of old tree-rings. This could mean that climatic signals become stronger (or weaker) with tree aging, or that the seasonality of signals or the sensitivity to a specific element (e.g., temperature, precipitation) changes over time. Such changes would affect the interpretation of dendroclimatic reconstructions, as the tree-rings included in these records are generally oldest at the end of a record (e.g., 21 st century)-which is the time period generally used for calibration with instrumental data. We here addressed this concern by analyzing young and old Pinus cembra trees from three high elevation sites in the central European Alps. Core and disc samples were collected in pre-defined plots to allow for a representative analysis of tree ages with tree-ring width (TRW) measurement series categorized into age classes (i) >1880, (ii) 1880-1939, and (iii) 1940-2002. Notably we report on the signal of the very young category (iii) not yet described in literature, and thus allow estimation of climate response and signal strength characteristics during the first years of the trees' lifespans. Comparison of age classes (i)-(iii) revealed differences in TRW coherence and size, but little change in climatic signal. CSAE are in the order of the differences recorded among high elevation sites-a conclusion that holds for inter-annual to decadal scale TRW variations at near-treepar Swiss stone pine. Such data are typically included in regional and larger-scale temperature reconstructions; thus, our results add confidence to long-term climate estimates integrating a range of tree-ring age classes. Other findings, such as the reaction wood in juvenile tree-rings, and sensitivity of the climate signal to sample replication, suggest that comparisons of young and old age classes, and separate calibration of these categories against instrumental climate data might further the estimation of long-term uncertainty changes in tree-ring based climate reconstructions. (C) 2008 Elsevier B.V. All rights reserved.

Ev015 Eveleigh, E. S. and Lucarotti, C. J. and McCarthy, P. C. and Morin, B. and Royama, T. and Thomas, A. W., 2007. Occurrence and effects of Nosema fumiferanae infections on adult spruce budworm caught above and within the forest canopy. Agric. For. Entomol., 9(4): 247-258.    Ev015.pdf      

Abstract: 1 Nosema fumiferanae infections in populations of both sexes of spruce budworm Choristoneura fumiferana moths, collected live above the forest canopy (canopy moths), within the tree crown (crown moths) and in drop trays (dead moths), were examined over a 5-year period in New Brunswick, Canada. 2 The incidence of infection and of moderate-heavy infections in canopy and crown moths of both sexes increased concomitantly with moth eclosion, indicating that N.fumiferanae retards larval/pupal development, with infected moths, particularly those having higher disease loads, emerging later in the season. 3 Infection rates differed among canopy, crown, and dead female, but not male, moths. Canopy (i.e. emigrating) females had a lower incidence of infection, lower incidence of moderate-heavy infections, and had longer forewings and higher dry weights, than crown females. These results suggest that N.fumiferanae infections negatively affect aspects of female, but not male, flight performance. Regardless of infection, forewing length and dry weight of both canopy and crown females decpard over the moth flight period, but infected females in both moth types were smaller than their uninfected counterparts. Forewing lengths and dry weights of moderately-heavily infected females were most severely affected. 4 Despite high annual infection rates in parents, only a small percentage of offspring (second-instar larvae) that established feeding sites each spring were infected, indicating that high rates of horizontal transmission occurred annually throughout the larval period. 5 The present study indicates that whether N.fumiferanae infections are a debilitating sublethal factor in spruce budworm populations depends more on the disease load than on the overall incidence of infection. The potential importance of N.fumiferanae infections on various fitness parameters related to host dispersal is discussed.

Fa019 Falkowski, P. and Scholes, R. J. and Boyle, E. and Canadell, J. and Canfield, D. and Elser, J. and Gruber, N. and Hibbard, K. and Högberg, P. and Linder, S. and Mackenzie, F. T. and Moore, III, B. and Pedersen, T. and Rosenthal, Y. and Seitzinger, S. and Smetacek, V. and Steffen, W., 2000. The global carbon cycle: a test of our knowledge of earth as a system. Science, 290(13.Oct.): 291-296.    Fa019.pdf   

Abstract: Motivated by the rapid increase in atmospheric CO2 due to human activities since the Industrial Revolution, several international scientific research programs have analyzed the role of individual components of the Earth system in the global carbon cycle. Our knowledge of the carbon cycle within the oceans, terrestrial ecosystems, and the atmosphere is sufficiently extensive to permit us to conclude that although natural processes can potentially slow the rate of increase in atmospheric CO2, there is no natural ``savior'' waiting to assimilate all the anthropogenically produced CO2 in the coming century. Our knowledge is insufficient to describe the interactions between the components of the Earth system and the relationship between the carbon cycle and other biogeochemical and climatological processes. Overcoming this limitation requires a systems approach.

Fa074 Fauria, M. M. and Johnson, E. A., 2009. Large-scale climatic patterns and area affected by mountain pine beetle in British Columbia, Canada. J. Geophys. Res. G, 114: G01012.    Fa074.pdf      

Abstract: We present evidence of high spatial synchrony in an area affected by mountain pine beetle (MPB, Dendroctonus ponderosae) across large distances in British Columbia, Canada, in a study of a spatially explicit database of an area affected by MPB-caused tree mortality for the period 1959-2002. We further show that large-scale climatic patterns (Pacific Decadal Oscillation (PDO) and, to a lesser degree, Arctic Oscillation (AO)) are strongly related to the observed MPB synchrony, and that they probably operate through controlling the frequency of extreme cold winter temperatures that affect MPB larvae survival. A smaller portion of the data's variability is linked to the onset of the two largest outbreaks in the studied period and might be attributed to dispersal from outbreak-prone areas or else to differences in microhabitat (e. g., host availability) in these regions. The onset of a warm PDO phase in 1976 favored MPB outbreaks by reducing the occurrence of extremely low winter temperatures province-wide. Likewise, the exceptionally high and persistent AO values of the late 1980s and 1990s enhanced MPB activity in the southern and northern parts of the region. Summer warmth cannot be discarded as an important agent at smaller scales.

Fe061 Feddema, J. J. and Oleson, K. W. and Bonan, G. B. and Mearns, L. O. and Buja, L. E. and Meehl, G. A. and Washington, W. M., 2005. The importance of land-cover change in simulating future climates. Science, 310(5754): 1674-1678.    Fe061.pdf      

Abstract: Adding the effects of changes in land cover to the A2 and B1 transient climate simulations described in the Special Report on Emissions Scenarios (SRES) by the Intergovernmental Panel on Climate Change leads to significantly different regional climates in 2100 as compared with climates resulting from atmospheric SRES forcings alone. Agricultural expansion in the A2 scenario results in significant additional warming over the Amazon and cooling of the upper air column and nearby oceans. These and other influences on the Hadley and monsoon circulations affect extratropical climates. Agricultural expansion in the mid-latitudes produces cooling and decreases in the mean daily temperature range over many areas. The A2 scenario results in more significant change, often of opposite sign, than does the B1 scenario.

Fi002 Fischlin, A. and Baltensweiler, W., 1979. Systems analysis of the larch bud moth system. Part I: the larch-larch bud moth relationship. Mitt. Schweiz. Ent. Ges., 52: 273-289.    Fi002.pdf   

Abstract: Cyclic fluctuations in the abundance of the larch bud moth, Z. diniana Gn. (Lep. Tortricidae) were studied in a program which treats the various hypotheses by means of systems analysis. Based on data from the laboratory and the Upper Engadine valley of Switzerland, the hypothesis proposing that the gradation cycles are caused by interaction between the host plant larch and the insect larch bud moth was modeled. In simulation studies the model's behavior was similar to that of the real system. Sensitivity analysis revealed this behavior to be sensitive to the recovery rate of the trees after defoliation. On this recovery process only scanty field data are available. Despite consistence of simulation results and observations, the hypothetical model can not be accepted nor rejected definitively. Because of a cycle of the system lasts about 9 yr, it is not possible to gather the needed measurements on the raw fiber content of the larch needles. By modeling all the hypotheses plus comparing the respective models, a basis is provided to decide unequivocally which hypothesis best explains the real larch bud moth system.

Fi04dg Fischlin, A. and Bugmann, H. and Gyalistras, D., 1995. Sensitivity of a forest ecosystem model to climate parametrization schemes. Environ. Pollut., 87(3): 267-282.    Fi04dg.pdf   

Abstract: An analysis of the climate parametrization scheme adopted by conventional forest gap models revealed that most models assume a constant climate and are difficult to calibrate consistently. Tree growth showed unrealistically sensitive threshold effects along ecological gradients of temperature and precipitation. A new parametrization was compared with its predecessors in terms of the model's capability to predict realistic steady state species compositions at three test sites in the Alps. Applying the new model variant to some climate-change scenarios suggests that forest gap models are highly sensitive to climate pametrizations, regardless of the realism with which they simulate forests for the current climate. Moreover, the precision of climate scenarios based on General Circulation Models (GCM), for example, falls short of 's sensitivity. Climate-dependent processes in forest gap models should be rehearsed before these models are used in impact studies of climatic change.

Fi012 Fischlin, A., 1983. Modelling of Alpine valleys, defoliated forests, and larch bud moth cycles: the rôle of migration. In: Lamberson, R. H. (eds.), Mathematical models of renewable resources. Humboldt State University, Mathematical Modelling Group, Proc. of the 2nd Pacific Coast Conf. on Mathematical Modelling of Renewable Resources, University of Victoria, Victoria, B.C., Canada, 102-104pp.
Fi027 Fischlin, A. and Chitty, D. G. and and Krebs, C. J., 1982. Small mammal cycles and the Chitty hypothesis. Can. J. Zool., : (unpublished).   
Fi037 Fischlin, A., 1991. Interactive modeling and simulation of environmental systems on workstations. In: Möller, D. P. F. and Richter, O. (eds.), Analysis of Dynamic Systems in Medicine, Biology, and Ecology. Springer, Proc. of the 4th Ebenburger Working Conference, Berlin a.o., 131-145pp.    Fi037.pdf   

Abstract: Many systems dealt with in environmental sciences such as ecology or environmental biology could be easily modelled and efficiently simulated on personal computers or on workstations. Thanks to their graphical capabilities such computers make it possible to model systems interactively, e.g. supported by graphical structure editors, or allow for interactive simulation featuring sophisticated graphical output of the simulation results. However, in practice this potential remains often underexploited, since traditional, simulation software is mostly batch oriented, largely ignores computer science research, and offers rarely the functionality needed for a sensible interactive use. Instead of porting simulation software from main-frames onto workstations we propose new concepts based on Wymore and Zeigler's modeling theory, enhanced by some new interactive user oriented task concepts. This paper presents a scheme called RAMSES for the architecture of a modeling and simulation environment on a workstation particularly suited for the working with environmental systems. Furthermore it reports on some results which have been obtained by implementing portions of the RAMSES architecture, in particular an open and extensible modeling and simulation environment for the two classical model formalisms SM (Sequential Machine), DESS (Differential Equation System Specification) featuring modular modeling. Finally the modeling and simulation of a system from population ecology is presented as an example to illustrate and evaluate some of the concepts of RAMSES in ecological research.

Fi047 Fischlin, A. and Gyalistras, D. and Roth, O. and Ulrich, M. and Thoeny, J. and Nemecek, T. and Bugmann, H. K. and Thommen, F., 1994. ModelWorks 2.2: An interactive simulation environment for personal computers and workstations. Systems Ecology Report, Institute of Terrestrial Ecology, Swiss Federal Institute of Technology ETH, Zurich, Switzerland, 324pp.    Fi047.pdf   

Abstract: ModelWorks is a modelling and simulation environment in Modula-2 specifically designed to be run interactively on modern personal computers and workstations. It supports modular modelling by featuring a coupling mechanism between submodels and an unrestricted number of state variables, model parameters etc. up to the limits of the computer resources. It allows for the formulation of continuous time, discrete time, discrete event models, as well as the free mixing of all these formalisms. Not only does ModelWorks offer the simulationist a handy user interface to experiment interactively with model systems, but also allows the modeller to use ModelWorks' functions via a client interface in any other programming context.

Fi065 Fischlin, A. and Gyalistras, D., 1997. Assessing impacts of climatic change on forests in the Alps. Global Ecol. Biogeogr. Lett., 6(1): 19-37.    Fi065.pdf    Fi065_S.pdf      

Abstract: This paper presents a method to project quantitatively the possible impacts of climatic change on mountain forests at high temporal (annual cycle), spatial, and qualitative resolution. It allows linkage from global scenarios simulated by climate models through local climatic scenarios to stand-specific forest models. The method was applied to four representative sites in the Alps using the CCC-GCMII climate model, a statistical procedure to downscale GCM-output to the regional scale, and the forest patch model ForClim. Sharply contrasting forest responses were observed within short distances under the same 2xCO2 scenario of radiative forcing. While some forest simulations produced only small changes in tree species composition, others produced major changes even to the point of a complete disappearance of the forest. In some cases new species assemblages emerged without any analogue under present conditions. The results suggest that some mountain forests are sensitive to a 2xCO2 global change, and that human assistance may be required to help forests to adapt. The proposed method made good use of existing data, integrated current understanding, and appears sufficiently flexible and general to assess impacts of climatic change on any mid to high latitude forests in accordance with IPCC guidelines.

Fi103 Fischlin, A. and Midgley, G. F. and Price, J. T. and Leemans, R. and Gopal, B. and Turley, C. and Rounsevell, M. D. A. and Dube, O. P. and Tarazona, J. and Velichko, A. A., 2007. Ecosystems, their properties, goods and services. In: Parry, M. L. and Canziani, O. F. and Palutikof, J. P. and van der Linden, P. J. and Hanson, C. E. (eds.), Climate change 2007: Impacts, adaptation and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel of Climate Change (IPCC). Cambridge University Press, Cambridge, UK, 211-272pp.    Fi103.pdf   
Fi148 Fischlin, A. and Ayres, M. and Karnosky, D. and S. Kellomäki, Louman, B. and Ong, C. and Plattner, G.-K. and Santoso, H. and Thompson, I., 2009. Future environmental impacts and vulnerabilities. In: Seppälä, R. and Buck, A. and Katila, P. (eds.), Adaptation of forests and people to climate change – A global assessment report. International Union of Forest Research Organizations (IUFRO), Prepared by the Global Forest Expert Panel on Adaptation of Forests to Climate Change, In press, Helsinki, Finland, 53-100pp.    Fi148.pdf    Fi148_S.pdf   

Abstract: The focus of this chapter is on climate change impacts on the environment, the structure and functioning of forests, on their biodiversity, and on the services and goods provided by forests in order to identify key vulnerabilities. Based on the findings of the IPCC Fourth Assessment Report (IPCC 2007d), we first introduce four clusters (unavoidable, stable, growth, and fast growth) of climate change scenarios commonly used to quantitatively assess climate change impacts (section 3.2). At the global scale (section 3.3) as well as in the four domains (boreal – section 3.4; temperate – 3.5; subtropical – 3.6; tropical – 3.7), our CCIAV-assessment (see glossary) for forests shows that many forests can adapt to a moderate climate change if water is sufficiently available, notably in currently temperature limited areas (unavoidable, lower end stable). In some temperate or boreal regions, certain forests can even increase their primary productivity in a moderate climate change. However, some of these benefits are easily offset as climate warms and the adaptive capacity of currently water limited, fire or insect prone forests is frequently exceeded already by a limited climate change (unavoidable, stable). Many other forests become also vulnerable to an unmitigated climate change (growth, fast growth) as their adaptive capacity is exceeded. Forests currently sequester significant amounts of carbon; a key vulnerability consists in the loss of this service, and forests may even turn into a net source. Among land ecosystems, forests currently house the largest fraction of biodiversity; unmitigated climate change threatens to put significant parts of it at risk. The boreal domain, being especially sensitive, serves as a model case and is treated in particular depth. Finally, conclusions are drawn to summarize all findings on the global as well as regional scales (section 3.8).

Fl027 Fleming, R. A. and Candau, J. N. and McAlpine, R. S., 2002. Landscape-scale analysis of interactions between insect defoliation and forest fire in Central Canada. Clim. Change, 55(1-2): 251-272.    Fl027.pdf      

Abstract: Analysis of Ontario's historical records from 1941-1996 showed that spruce budworm, Choristoneura fumiferana (Clem.) caused whole tree mortality within 389x10(3) km(2). This amounted to 9.2% of the annually cumulative area with moderate-severe defoliation. Large (>2 km(2)) fires were reported in approximately 65,000 km(2) and overlapped only 2.8% of the area of reported spruce budworm (SBW) caused tree mortality. Within the 417x 10(3) km(2) defoliated by SBW at least once in 1941-1996, the maximum total area recorded as defoliated in any year was over 20 times the maximal area burnt. In the 19,950 km(2) experiencing both wildfire and SBW defoliation, analysis of the spectra of time lags between the two disturbance types indicated that fires occurred 3-9 years after a SBW outbreak disproportionately often. This 'window of opportunity' for wildfire varies geographically: it starts later after SBW outbreak and lasts longer in western than in eastern Ontario. In addition, 7.5% of the areas containing SBW killed trees were burnt in western compared to 4.8% in eastern Ontario. These geographical differences may result at least partly from slower decomposition of dead fuels in the drier climates of the western SBW belt compared to the eastern SBW belt. The implications for climatic change are discussed.

Fl028 Fleming, R. A. and Candau, J.-N., 2004. Climate change and insect outbreaks. In: Gauthier, S. and Gray, D. R. andLi, C. (eds.), Effects of climate change on major forest disturbances (fire, insects) and their impact on biomass production in Canada: Synthesis of the current state of knowledge. Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, Workshop, Quebec, 8-12pp.    Fl028.pdf   
Fl029 Fleming, R. A., 2000. Climate change and insect disturbance regimes in Canada's boreal forests. World Resource Rev., 12(3): 520-555.    Fl029.pdf

Abstract: Natural disturbances are integral processes in the succession, functioning, and carbon-cycling that occurs in most of the world's boreal forests. Insects represent dominating disturbance factors in Canada's boreal forests and during outbreaks trees are often killed over vast areas. This extensive tree mortality shifts the forest toward younger age-classes which contain less biomass and much of the residual carbon is later released to the atmosphere. A fundamental question is whether climate change will increase the frequency, duration, and intensity of natural disturbances and thus accelerate the rate of warming. Climate change will likely transform the damage patterns caused by many insects and the resulting uncertainties directly affect depletion forecasts, pest hazard rating procedures, and long-term planning for harvest queues and pest control requirements. Because the potential for wildfire often increases in stands after insect attack, uncertainties in future insect damage patterns magnify uncertainties in fire regimes. In addition, insects are important contributors to carbon and nutrient cycling, to biomass decomposition, and to energy flow, and changes in damage patterns can indirectly alter competitive relationships between plants and hence successional pathways, species composition, and forest distribution. The disturbance regimes associated with three of the most important insects of Canada's boreal forest are described. The assumption of integrated ecosystem response is used to develop scenarios of how the disturbance regimes of a number of boreal forest insects might respond to climate change. Methods for improving the incorporation of insect disturbance regimes in carbon budget estimates for Canada's boreal forests are outlined and concepts underpinning a number of proposed approaches to managing insect disturbance regimes to improve carbon storage and sustain other values and benefits of the boreal resource are briefly discussed. An unresolved issue is the trade-off implicit in any approach, be it large-scale planting or protection from insects and fire, which uses fossil fuels. Any short-term increase in the sequestration of atmospheric carbon by the forest comes at a cost of additional carbon imported into the modern biospheric system for the long term. Some research approaches for filling key information gaps are briefly suggested.

Fl032 Fleming, R. A. and Barclay, H. J. and Candau, J. N., 2002. Scaling-up an autoregressive time-series model (of spruce budworm population dynamics) changes its qualitative behavior. Ecol. Model., 149(1-2): 127-142.    Fl032.pdf      

Abstract: The emergence of issues such as climate change has motivated the development of time-dependent models to forecast how plant and animal populations will react over large spatial extents. Usually the best data available for constructing such models comes from intensive, detailed field studies. Models, thus implicitly developed at the fine spatial resolution of experimental studies, are then scaled-up to coarser resolution for management decision-making. Typically, this process of scaling-up involves merely adapting the models computer code for data input so that it will accept the large scale spatial averages (often derived from relatively remote (e.g. aerial) sensing) that form the basis for management planning. Unfortunately, such scaling-up can inadvertently affect model predictions and dynamical behavior. Improper incorporation of data collected at multiple resolutions during model development and use, and misinterpretation of model output can result. The consequences of scaling-up a linear, second-order, autoregressive. time series model of spruce budworm population dynamics on the model's predictions and on the interpretation of the model's output are considered. Such time series models have been proposed as templates for incorporating outbreak dynamics in the decision systems supporting forest insect management that tire currently being adapted to climatic change problems. Analysis of the underlying deterministic component of the time series model showed that: (1) parameter estimates changed with the spatial resolution-parameter values estimated from time series data consisting of large area averages were negatively correlated (r = -0.931, P<0.0005) and as much as 40 or 50 times greater in absolute value than the parameters generating the fine resolution data from sampling sites 1600 times smaller in extent. (2) Even the qualitative nature of the dynamics appeared to change in response to scaling-up. The long cycle, converging oscillations generated at fine resolutions gave way to five additional types of qualitative behavior at coarser resolutions including various types of divergent behavior and non-oscillating behavior. (3) The amount of distortion involved in scaling-up depends on the model's degree of non-linearity and on the fine scale spatial variation in population densities. An approach to correcting for such distortion is outlined. The potential consequences of scaling-up deserve consideration whenever data measured at different spatial resolutions are integrated during model development. as often happens in climate change research. (C) 2002 Elsevier Science B.V. All rights reserved.

Fl033 Fleming, R. A. and Candau, J. N., 1998. Influences of climatic change on some ecological processes of an insect outbreak system in Canada's boreal forests and the implications for biodiversity. Environ. Monitor. Assess., 49(2-3): 235-249.    Fl033.pdf      

Abstract: Insect outbreaks are a major disturbance factor in Canadian forests. If global warming occurs, the disturbance patterns caused by insects may change substantially, especially for those insects whose distributions depend largely on climate. In addition, the likelihood of wildfire often increases after insect attack, so the unpredictability of future insect disturbance patterns adds to the general uncertainty of fire regimes. The rates of processes fundamental to energy, nutrient, and biogeochemical cycling are also affected by insect disturbance, and through these effects, potential changes in disturbance patterns indirectly influence biodiversity. A process-level perspective is advanced to describe how the major insect outbreak system in Canadian forests, that of the spruce budworm (Choristoneura fumiferana Clem. [Lepidoptera: Tortricidae]), might react to global warming. The resulting scenarios highlight the possible importance of natural selection, extreme weather, phenological relationships, complex feedbacks, historical conditions, and threshold behavior. That global warming already seems to be affecting the lifecycles of some insects points to the timeliness of this discussion. Some implications of this process-level perspective for managing the effects of global warming on biodiversity are discussed. The value of process-level understanding and high-resolution, long-term monitoring in attacking such problems is emphasized. It is argued that a species-level, preservationist approach may have unwanted side-effects, be cost-ineffective, and ecologically unsustainable.

Fl044 Fleming, R. A., 2000. Climate change and insect disturbance regimes in Canada's boreal forests. In: Shen, S. (eds.), Global Warming Science & Policy. Supcon International, Proceedings of 11th Global Warming International Conference & Expo (GW11), Woodridge, IL, USA, 521-555pp.    Fl044.pdf   

Abstract: Natural disturbances are integral processes in the succession, functioning, and carbon-cycling that occurs in most of the world's boreal forests. Insects represent dominating disturbance factors in Canada's boreal forests and during outbreaks trees are often killed over vast areas. This extensive tree mortality shifts the forest toward younger age-classes which contain less biomass and much of the residual carbon is later released to the atmosphere. A fundamental question is whether climate change will increase the frequency, duration, and intensity of natural disturbances and thus accelerate the rate of warming. Climate change will likely transform the damage patterns caused by many insects and the resulting uncertainties directly affect depletion forecasts, pest hazard rating procedures, and long-term planning for harvest queues and pest control requirements. Because the potential for wildfire often increases in stands after insect attack, uncertainties in future insect damage patterns magnify uncertainties in fire regimes. In addition, insects are important contributors to carbon and nutrient cycling, to biomass decomposition, and to energy flow, and changes in damage patterns can indirectly alter competitive relationships between plants and hence successional pathways, species composition, and forest distribution. The disturbance regimes associated with three of the most important insects of Canada's boreal forest are described. The assumption of integrated ecosystem response is used to develop scenarios of how the disturbance regimes of a number of boreal forest insects might respond to climate change. Methods for improving the incorporation of insect disturbance regimes in carbon budget estimates for Canada's boreal forests are outpard and concepts underpinning a number of proposed approaches to managing insect disturbance regimes to improve carbon storage and sustain other values and benefits of the boreal resource are briefly discussed. An unresolved issue is the trade-off implicit in any approach, be it large-scale planting or protection from insects and fire, which uses fossil fuels. Any short-term increase in the sequestration of atmospheric carbon by the forest comes at a cost of additional carbon imported into the modern biospheric system for the long term. Some research approaches for filling key information gaps are briefly suggested.

Fo017 Foley, J. A. and Kutzbach, J. E. and Coe, M. T. and Levis, S., 1994. Feedbacks between climate and boreal forests during the Holocene epoche. Nature, 371(6492): 52-54.    Fo017.pdf   

Abstract: PREVIOUS studies15 have demonstrated that the predictions of global climate models are highly sensitive to large changes in vegetation cover, such as the complete removal of tropical or boreal forests. Although these studies have illustrated the potential effects of massive deforestation on the climate system, vegetation changes of this scale are very unlikely to occur. Investigating past environments may better illustrate the possible interactions between climate and vegetation cover. For example, palaeobotanical evidence indicates that 6,000 years ago boreal forests extended north of the modern treeline6, apparently in response to high-latitude warming resulting from variations in the Earth's orbit7,8. The expanded boreal forests, which took the place of tundra, must also have affected climate by significantly reducing the surface albedo5. Here we use a global climate model to examine the relative effects of orbitally-induced insolation variations and of the northward extension of boreal forests on the mid-Holocene climate. Orbital variations alone warm the high latitudes by 2 $\,^{\circ}$C or more in summer, autumn and winter. The subsequent northward extension of boreal forests gives rise to an additional warming of approximately 4 $\,^{\circ}$C in spring and about 1 $\,^{\circ}$C in the other seasons. This suggests that large positive feedbacks between climate and boreal forests may have taken place in the recent geological past.

Fo023 Foley, J. A. and Prentice, C. I. and Ramankutty, N. and Levis, S. and Pollard, D. and Sitch, S. and Haxeltine, A., 1996. An integrated biosphere model of land surface processes, terrestrial carbon balance, and vegetation dynamics. Global Biogeochem. Cycles, 10(4): 603-628.    Fo023.pdf   

Abstract: Here we present a new terrestrial biosphere model (the Integrated BIosphere Simulator-IBIS) which demonstrates how land surface biophysics, terrestrial carbon fluxes, and global vegetation dynamics can be represented in a single, physically consistent modeling framework. In order to integrate a wide range of biophysical, physiological, and ecological processes, the model is designed around a hierarchical, modular structure and uses a common state description throughout. First, a coupled simulation of the surface water, energy, and carbon fluxes is performed on hourly timesteps and is integrated over the year to estimate the annual water and carbon balance. Next, the annual carbon balance is used to predict changes in the leaf area index and biomass for each of nine plant functional types, which compete for light and water using different ecological strategies. The resulting patterns of annual evapotranspiration, runoff, and net primary productivity are in good agreement with observations. In addition, the model simulates patterns of vegetation dynamics that qualitatively agree with features of the natural process of secondary succession. Comparison of the model's inferred near-equilibrium vegetation categories with a potential natural vegetation map shows a fair degree of agreement. This integrated modeling framework provides a means of simulating both rapid biophysical processes and long-term ecosystem dynamics that can be directly incorporated within atmospheric models. © American Geophysical Union 1996

Fo024 Foley, J. A. and Levis, S. and Prentice, C. I. and Pollard, D. and Thompson, S. L., 1998. Coupling dynamic models of climate and vegetation. Global Change Biol., 4: 561-679.    Fo024.pdf      

Abstract: Numerous studies have underscored the importance of terrestrial ecosystems as an integral component of the Earth's climate system. This realization has already led to efforts to link simple equilibrium vegetation models with Atmospheric General Circulation Models through iterative coupling procedures. While these linked models have pointed to several possible climatevegetation feedback mechanisms, they have been limited by two shortcomings: (i) they only consider the equilibrium response of vegetation to shifting climatic conditions and therefore cannot be used to explore transient interactions between climate and vegetation; and (ii) the representations of vegetation processes and land-atmosphere exchange processes are still treated by two separate models and, as a result, may contain physical or ecological inconsistencies. Here we present, as a proof concept, a more tightly integrated framework for simulating global climate and vegetation interactions. The prototype coupled model consists of the GENESIS (version 2) Atmospheric General Circulation Model and the IBIS (version 1) Dynamic Global Vegetation Model. The two models are directly coupled through a common treatment of land surface and ecophysiological processes, which is used to calculate the energy, water, carbon, and momentum fluxes between vegetation, soils, and the atmosphere. On one side of the interface, GENESIS simulates the physics and general circulation of the atmosphere. On the other side, IBIS predicts transient changes in the vegetation structure through changes in the carbon balance and competition among plants within terrestrial ecosystems. As an initial test of this modelling framework, we perform a 30 year simulation in which the coupled model is supplied with modern CO2 concentrations, observed ocean temperatures, and modern insolation. In this exploratory study, we run the GENESIS atmospheric model at relatively coarse horizontal resolution (4.5$\,^{\circ}$ latitude by 7.5$\,^{\circ}$ longitude) and IBIS at moderate resolution (2$\,^{\circ}$ latitude by 2$\,^{\circ}$ longitude). We initialize the models with globally uniform climatic conditions and the modern distribution of potential vegetation cover. While the simulation does not fully reach equilibrium by the end of the run, several general features of the coupled model behaviour emerge. We compare the results of the coupled model against the observed patterns of modern climate. The model correctly simulates the basic zonal distribution of temperature and precipitation, but several important regional biases remain. In particular, there is a significant warm bias in the high northern latitudes, and cooler than observed conditions over the Himalayas, central South America, and north-central Africa. In terms of precipitation, the model simulates drier than observed conditions in much of South America, equatorial Africa and Indonesia, with wetter than observed conditions in northern Africa and China. Comparing the model results against observed patterns of vegetation cover shows that the general placement of forests and grasslands is roughly captured by the model. In addition, the model simulates a roughly correct separation of evergreen and deciduous forests in the tropical, temperate and boreal zones. However, the general patterns of global vegetation cover are only approximately correct: there are still significant regional biases in the simulation. In particular, forest cover is not simulated correctly in large portions of central Canada and southern South America, and grasslands extend too far into northern Africa. These preliminary results demonstrate the feasibility of coupling climate models with fully dynamic representations of the terrestrial biosphere. Continued development of fully coupled climate-vegetation models will facilitate the exploration of a broad range of global change issues, including the potential role of vegetation feedbacks within the climate system, and the impact of climate variability and transient climate change on the terrestrial biosphere.

Fo052 Foley, J. A. and Ramankutty, N., 2004. A primer on the terrestrial carbon cycle: What we don't know but should. In: Field, C. B. and Raupach, M. R. (eds.), The global carbon cycle - Integrating humans, climate and the natural world. Island Press, Washington, D.C., 279-294pp.    Fo052.pdf   

Fr035 Friend, A. D. and Steven, A. K. and Knox, R. G. and Cannell, M. G. R., 1997. A process-based terrestrial biosphere model of ecosystem dynamics (Hybrid v3.0). Ecol. Model., 95(2-3): 249-287.    Fr035.pdf   

Abstract: A numerical process-based model of terrestrial ecosystem dynamics is described and tested. The model, Hybrid v3.0, treats the daily cycling of carbon, nitrogen, and water within the biosphere and between the biosphere and the atmosphere. It combines a mass-balance approach with the capacity to predict the relative dominance of different species or generalised plant types (such as evergreen needleleaved trees, cold deciduous broadleaved trees, and C3 grasses). The growth of individual trees is simulated on an annual timestep, and the growth of a grass layer is simulated on a daily timestep. The exchange of carbon, nitrogen, and water with the atmosphere and the soil is simulated on a daily timestep (except the flux of tree litter to the soil, which occurs annually). Individual trees and the grass layer compete with each other for light, water, and nitrogen within a `plot'. Larger and taller plants shade smaller ones; they also take up a greater proportion of the available water and nitrogen. The above-ground space in each plot is divided into 1 m deep layers for the purposes of calculating irradiance interception; horizontal variation in the plot environment is not treated. The soil is represented as a single layer, with a daily hydrological budget. Decomposition of soil organic matter is calculated using an empirical sub-model. The initial size of each tree seedling is stochastic. To predict the mean behaviour of the model for a particular boundary condition it is necessary to simulate a number of plots. Hybrid v3.0 has been written with three major requirements in mind: (i) the carbon, water, and nutrient cycles must be fully coupled in the soil-plant-atmosphere system; (ii) the internal constraints on the model's behaviour, and the driving forces for the model, must be the same as those which operate in nature (e.g., climate, nitrogen deposition, and the atmospheric concentrations of CO2 and O2); and (iii) the model must be constructed so that it is capable of predicting transient as well as equilibrium responses to climate change. These conditions have largely been met by constructing the model around a set of fundamental hypotheses regarding the general constraints under which plants and soils behave, independently of any particular location or time. The model is thus potentially capable of making reliable predictions of ecosystem behaviour and structure under future, new, atmospheric conditions. The model is tested for a site in eastern North America. A quasi-equilibrium is reached after approximately 250 years with 10 plots. It is found that more plots are not necessary in order to obtain a reliable estimate of mean behaviour. Predictions of productivity, leaf area index, foliage nitrogen, soil carbon, and biomass carbon are all within the range expected for this location. Mortality is shown to be a necessary model component; without it large trees reach a maximum size, and then remain in dynamic equilibrium with the climate, without dying. The model runs at a rate of 0.176 s plot-1 year-1 on a workstation (a 500 year simulation, with 10 plots, thus takes approximately 15 min). A sensitivity analysis demonstrates the importance of the parameterisation of phenology, photosynthesis, and foliage/fine root carbon and nitrogen partitioning for the overall carbon balance of the modelled ecosystem. Hybrid v3.0 has been written with the intention of using it to represent the terrestrial biosphere in a total earth system model. This would be achieved by linking it to models of other components of the earth system, such as the climate and the oceans, in a fully coupled manner. This total earth system model could then be used to answer a large range of questions concerning global environmental change.

Fr055 Friedlingstein, P. and Cox, P. and Betts, R. and Bopp, L. and Von Bloh, W. and Brovkin, V. and Cadule, P. and Doney, S. and Eby, M. and Fung, I. and Bala, G. and John, J. and Jones, C. and Joos, F. and Kato, T. and Kawamiya, M. and Knorr, W. and Lindsay, K. and Matthews, H. D. and Raddatz, T. and Rayner, P. and Reick, C. and Roeckner, E. and Schnitzler, K. G. and Schnur, R. and Strassmann, K. and Weaver, A. J. and Yoshikawa, C. and Zeng, N., 2006. Climate-carbon cycle feedback analysis: Results from the C4MIP model intercomparison. J. Clim., 19(14): 3337-3353.    Fr055.pdf    Fr055_S.pdf      

Abstract: Eleven coupled climate-carbon cycle models used a common protocol to study the coupling between climate change and the carbon cycle. The models were forced by historical emissions and the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A2 anthropogenic emissions of CO2 for the 1850-2100 time period. For each model, two simulations were performed in order to isolate the impact of climate change on the land and ocean carbon cycle, and therefore the climate feedback on the atmospheric CO2 concentration growth rate. There was unanimous agreement among the models that future climate change will reduce the efficiency of the earth system to absorb the anthropogenic carbon perturbation. A larger fraction of anthropogenic CO2 will stay airborne if climate change is accounted for. By the end of the twenty-first century, this additional CO2 varied between 20 and 200 ppm for the two extreme models, the majority of the models lying between 50 and 100 ppm. The higher CO2 levels led to an additional climate warming ranging between 0.1 degrees and 1.5 degrees C. All models simulated a negative sensitivity for both the land and the ocean carbon cycle to future climate. However, there was still a large uncertainty on the magnitude of these sensitivities. Eight models attributed most of the changes to the land, while three attributed it to the ocean. Also, a majority of the models located the reduction of land carbon uptake in the Tropics. However, the attribution of the land sensitivity to changes in net primary productivity versus changes in respiration is still subject to debate; no consensus emerged among the models.

Fr084 Friedenberg, N. A. and Sarkar, S. and Kouchoukos, N. and Billings, R. F. and Ayres, M. P., 2008. Temperature extremes, density dependence, and southern pine beetle (Coleoptera : Curculionidae) population dynamics in east Texas. Environ. Entomol., 37(3): 650-659.    Fr084.pdf      

Abstract: Previous studies of the southern pine beetle, Dendroctonus frontalis Zimm., established that its population in east Texas responds to a delayed density-dependent process, whereas no clear role of climate has been determined. We tested two biological hypotheses for the influence of extreme temperatures on annual southern pine beetle population growth in the context of four alternative hypotheses for density-dependent population regulation. The significance of climate variables and their interaction with population regulation depended on the model of density dependence. The best model included both direct and delayed density dependence of a cubic rather than linear form. Population growth declined with the number of days exceeding 32 degrees C, temperatures previously reported to reduce brood survival. Density dependence also changed with the number of hot days. Growth was highest in years with average minimum winter temperatures. Severely cold winters may reduce Survival, whereas warm winters may reduce the efficiency of spring infestation formation. Whereas most previous studies have incorporated climate as an additive effect on growth, we found that the form of delayed density dependence changed with the number of days > 32 degrees C. The interaction between temperature and regulation, a potentially common phenomenon in ecology, may explain why southern pine beetle outbreaks do not occur at perfectly regular intervals. Factors other than climate, such as forest management and direct suppression, may have contributed significantly to the timing, severity, and eventual cessation of outbreaks since the mid-1950s.

Fr104 Friedlingstein, P. and Houghton, R. A. and Marland, G. and Hackler, J. and Boden, T. A. and Conway, T. J. and Canadell, J. G. and Raupach, M. R. and Ciais, P. and Le Quere, C., 2010. Update on CO2 emissions. Nature Geosci., 3(12): 811-812.    Fr104.pdf      

Abstract: Emissions of CO2 are the main contributor to anthropogenic climate change. Here we present updated information on their present and near-future estimates. We calculate that global CO2 emissions from fossil fuel burning decreased by 1.3% in 2009 owing to the global financial and economic crisis that started in 2008; this is half the decrease anticipated a year ago1. If economic growth proceeds as expected2, emissions are projected to increase by more than 3% in 2010, approaching the high emissions growth rates that were observed from 2000 to 20081, 3, 4. We estimate that recent CO2 emissions from deforestation and other land-use changes (LUCs) have decpard compared with the 1990s, primarily because of reduced rates of deforestation in the tropics5 and a smaller contribution owing to forest regrowth elsewhere.

Fr106 Frank, D. C. and Esper, J. and Raible, C. C. and Buentgen, U. and Trouet, V. and Stocker, B. and Joos, F., 2010. Ensemble reconstruction constraints on the global carbon cycle sensitivity to climate. Nature, 463(7280): 527-U143.    Fr106.pdf      

Abstract: The processes controlling the carbon flux and carbon storage of the atmosphere, ocean and terrestrial biosphere are temperature sensitive(1-4) and are likely to provide a positive feedback leading to amplified anthropogenic warming(3). Owing to this feedback, at time-scales ranging from interannual to the 20-100-kyr cycles of Earth's orbital variations(1,5-7), warming of the climate system causes a net release of CO2 into the atmosphere; this in turn amplifies warming. But the magnitude of the climate sensitivity of the global carbon cycle (termed gamma), and thus of its positive feedback strength, is under debate, giving rise to large uncertainties in global warming projections(8,9). Here we quantify the median gamma as 7.7 p. p. m. v. CO2 per degrees C warming, with a likely range of 1.7-21.4 p. p. m. v. CO2 per degrees C. Sensitivity experiments exclude significant influence of pre-industrial land-use change on these estimates. Our results, based on the coupling of a probabilistic approach with an ensemble of proxy-based temperature reconstructions and pre-industrial CO2 data from three ice cores, provide robust constraints for gamma on the policy-relevant multi-decadal to centennial timescales. By using an ensemble of >200,000 members, quantification of gamma is not only improved, but also likelihoods can be assigned, thereby providing a benchmark for future model simulations. Although uncertainties do not at present allow exclusion of gamma calculated from any of ten coupled carbon-climate models, we find that gamma is about twice as likely to fall in the lowermost than in the uppermost quartile of their range. Our results are incompatibly lower (P < 0.05) than recent pre-industrial empirical estimates of similar to 40 p. p. m. v. CO2 per degrees C (refs 6, 7), and correspondingly suggest similar to 80\% less potential amplification of ongoing global warming.

Fr107 Fraver, S. and Seymour, R. S. and Speer, J. H. and White, A. S., 2007. Dendrochronological reconstruction of spruce budworm outbreaks in northern Maine, USA. Can. J. Forest Res., 37(3): 523-529.    Fr107.pdf      

Abstract: Using dendrochronological analyses, we reconstructed a 300 year history of eastern spruce budworm (Choristoneura fumiferana (Clem.)) outbreaks in northern interior Maine. By analyzing radial growth patterns from the budworm host, red spruce (Picea rubens Sarg.), and nonhost, northern white cedar (Thuja occidentalis L.), we identified five outbreaks beginning ca. 1709, 1762, 1808, 1914, and 1976. all of which have been documented from eastern Canada. However, little or no evidence was found in our study for the 1830s, 1870s, or 1940s Outbreaks also documented there. The mean outbreak return interval in our Study (67 years) was roughly twice that postulated for eastern Canada. Differences in forest types, and associated stand dynamics, between the regions may explain the longer return intervals, and consequently the absence of these three Outbreaks in Maine. Results also indicate that small, slow-growing trees exhibit a budworm signal very similar to that of overstory trees, once tree-ring series have been properly standardized.

Fr109 Franke, J. and Gonzalez-Rouco, J. and Frank, D. and Graham, N., 2011. 200 years of European temperature variability: insights from and tests of the proxy surrogate reconstruction analog method. Clim. Dyn., 37: 133-150.    Fr109.pdf   

Abstract: Spatially resolved climate reconstructions are commonly derived from long instrumental series and proxy data via parar regression based approaches that use the main modes of the climate system. Such reconstructions have been shown to underestimate climate variability and are based upon the assumption that the main modes of climate variability are stationary back in time. Climate models simulate physically consistent climate fields but cannot be taken to represent the real past climate trajectory because of their necessarily simplified scope and chaotic internal variability. Here, we present sensitivity tests of, and a 200-year temperature reconstruction from, the PSR (Proxy Surrogate Reconstruction) method. This method simultaneously capitalizes on the individual strengths of instrumental/proxy data based reconstructions and model simulations by selecting the model states (analogs) that are most similar with proxy/instrumental data available at specific places and specific moments of time. Sensitivity experiments reveal an optimal PSR configuration and indicate that 6,500 simulation years of existing climate models provide a sufficient pool of possible analogs to skillfully reconstruct monthly European temperature fields during the past 200 years. Reconstruction verification based upon only seven instrumental stations indicates potential for extensions back in time using sparse proxy data. Additionally the PSR method allows evaluation of single time series, in this case the homogeneity of instrumental series, by identifying inconsistencies with the reconstructed climate field. We present an updated European temperature reconstruction including newly homogenized instrumental records performed with the computationally efficient PSR method that proves to capture the total variance of the target.

Fr112 Frank, D. and Esper, J. and Zorita, E. and Wilson, R., 2010. A noodle, hockey stick, and spaghetti plate: a perspective on high-resolution paleoclimatology. Wiley Interdisciplinary Rev. Clim. Change, 1(4): 507-516.    Fr112.pdf      

Abstract: The high-resolution reconstruction of hemispheric-scale temperature variation over the past-millennium benchmarks recent warming against more naturally driven climate episodes, such as the Little Ice Age and the Medieval Warm Period, thereby allowing assessment of the relative efficacies of natural and anthropogenic forcing factors. Icons of past temperature variability, as featured in the Intergovernmental Panel on Climate Change (IPCC) reports over nearly two decades, have changed from a schematic sketch in 1990, to a seemingly well-solved story in 2001, to more explicit recognition of significant uncertainties in 2007. In this article, we detail the beginning of the movement to reconstruct large-scale temperatures, highlight major steps forward, and present our views on what remains to be accomplished. Despite significant efforts and progress, the spatial representation of reconstructions is limited, and the interannual and centennial variation are poorly quantified. Research priorities to reduce reconstruction uncertainties and improve future projections, include (1) increasing the role of expert assessment in selecting and incorporating the highest quality proxy data in reconstructions (2) employing reconstruction ensemble methodology, and (3) further improvements of forcing series. We suggest that much of the sensitivity in the reconstructions, a topic that has dominated scientific debates, can be traced back to the input data. It is perhaps advisable to use fewer, but expert-assessed proxy records to reduce errors in future reconstruction efforts. (C) 2010 John Wiley \& Sons, Ltd. WIREs Clim Change 2010 1 507-516

Ge042 Gerten, D. and Schaphoff, S. and Haberlandt, U. and Lucht, W. and Sitch, S., 2004. Terrestrial vegetation and water balance - hydrological evaluation of a dynamic global vegetation model. J. Hydrol., 286(1-4): 249-270.    Ge042.pdf      

Abstract: Earth's vegetation plays a pivotal role in the global water balance. Hence, there is a need to model dynamic interactions and feedbacks between the terrestrial biosphere and the water cycle. Here, the hydrological performance of the Lund-Potsdam-Jena model (LPJ), a prominent dynamic global vegetation model, is evaluated. Models of this type simulate the coupled terrestrial carbon and water cycle, thus they are well suited for investigating biosphere-hydrosphere interactions over large domains. We demonstrate that runoff and evapotranspiration computed by LPJ agree well with respective results from state-of-the-art global hydrological models, while in some regions, runoff is significantly over- or underestimated compared to observations. The direction and magnitude of these biases is largely similar to those from other macro-scale models, rather than specific to LPJ. They are attributable primarily to uncertainties in the climate input data, and to human interventions not considered by the model (e.g. water withdrawal, land cover conversions). Additional model development is required to perform integrated assessments of water exchanges among the biosphere, the hydrosphere, and the anthroposphere. Yet, the LPJ model can now be used to study inter-relations between the world's major vegetation types and the terrestrial water balance. As an example, it is shown that a doubling of atmospheric CO2 content alone would result in pronounced changes in evapotranspiration and runoff for many parts of the world. Although significant, these changes would remain unseen by stand-alone hydrological models, thereby emphasizing the importance of simulating the coupled carbon and water cycle. (C) 2003 Elsevier B.V. All rights reserved.

Gi052 Gilg, O. and Hanski, I. and Sittler, B., 2003. Cyclic dynamics in a simple vertebrate predator-prey community. Science, 302(5646): 866-868.    Gi052.pdf      

Abstract: The collared lemming in the high-Arctic tundra in Greenland is preyed upon by four species of predators that show marked differences in the numbers of lemmings each consumes and in the dependence of their dynamics on lemming density. A predator prey model based on the field-estimated predator responses robustly predicts 4-year periodicity in lemming dynamics, in agreement with long-term empirical data. There is no indication in the field that food or space limits lemming population growth, nor is there need in the model to consider those factors. The cyclic dynamics are driven by a 1-year delay in the numerical response of the stoat and stabilized by strongly density-dependent predation by the arctic fox, the snowy owl, and the long-tailed skua.

Go112 Goodale, C. L. and Apps, M. J. and Birdsey, R. A. and Field, C. B. and Heath, L. S. and Houghton, R. A. and Jenkins, J. C. and Kohlmaier, G. H. and Kurz, W. and Liu, S. R. and Nabuurs, G. J. and Nilsson, S. and Shvidenko, A. Z., 2002. Forest carbon sinks in the Northern Hemisphere. Ecol. Appl., 12(3): 891-899.    Go112.pdf      

Abstract: There is general agreement that terrestrial systems in the Northern Hemisphere provide a significant sink for atmospheric CO2; however, estimates of the magnitude and distribution of this sink vary greatly. National forest inventories provide strong, measuretment-based constraints on the magnitude of net forest carbon uptake. We brought together forest sector C budgets for Canada, the United States, Europe, Russia, and China that were derived from forest inventory information, allometric relationships, and supplementary data sets and models. Together, these suggest that northern forests and woodlands provided a total sink for 0.6-0.7 Pg of C per year (1 Pg = 10(15) g) during the early 1990s, consisting of 0.21 Pg C/yr in living biomass, 0.08 Pg C/yr in forest products, 0.15 Pg C/yr in dead wood, and 0.13 Pg C/yr in the forest floor and soil organic matter. Estimates of changes in soil C pools have improved but remain the least certain terms of the budgets. Over 80% of the estimated sink occurred in one-third of the forest area, in temperate regions affected by fire suppression, agricultural abandonment, and plantation forestry. Growth in boreal regions was offset by fire and other disturbances that vary considerably from year to year. Comparison with atmospheric inversions suggests significant land C sinks may occur outside the forest sector.

Gr074 Gruber, N. and Keeling, C. D. and Bates, N. R., 2002. Interannual variability in the North Atlantic Ocean carbon sink. Science, 298(5602): 2374-2378.    Gr074.pdf      

Abstract: The North Atlantic is believed to represent the largest ocean sink for atmospheric carbon dioxide in the Northern Hemisphere, yet little is known about its temporal variability. We report an 18-year time series of upper-ocean inorganic carbon observations from the northwestern subtropical North Atlantic near Bermuda that indicates substantial variability in this sink. We deduce that the carbon variability at this site is largely driven by variations in winter mixed-layer depths and by sea surface temperature anomalies. Because these variations tend to occur in a basinwide coordinated pattern associated with the North Atlantic Oscillation, it is plausible that the entire North Atlantic Ocean may vary in concert, resulting in a variability of the strength of the North Atlantic carbon sink of about +/-0.3 petagrams of carbon per year (1 petagram=10(15) grams) or nearly +/-50%. This extrapolation is supported by basin-wide estimates from atmospheric carbon dioxide inversions.

Gr199 Gregory, J. M. and Jones, C. D. and Cadule, P. and Friedlingstein, P., 2009. Quantifying carbon cycle feedbacks. J. Clim., 22(19): 5232-5250.    Gr199.pdf    Gr199_S.pdf      

Abstract: Perturbations to the carbon cycle could constitute large feedbacks on future changes in atmospheric CO2 concentration and climate. This paper demonstrates how carbon cycle feedback can be expressed in formally similar ways to climate feedback, and thus compares their magnitudes. The carbon cycle gives rise to two climate feedback terms: the concentration-carbon feedback, resulting from the uptake of carbon by land and ocean as a biogeochemical response to the atmospheric CO2 concentration, and the climate-carbon feedback, resulting from the effect of climate change on carbon fluxes. In the earth system models of the Coupled Climate-Carbon Cycle Model Intercomparison Project (C4MIP), climate-carbon feedback on warming is positive and of a similar size to the cloud feedback. The concentration-carbon feedback is negative; it has generally received less attention in the literature, but in magnitude it is 4 times larger than the climate-carbon feedback and more uncertain. The concentration-carbon feedback is the dominant uncertainty in the allowable CO2 emissions that are consistent with a given CO2 concentration scenario. In modeling the climate response to a scenario of CO2 emissions, the net carbon cycle feedback is of comparable size and uncertainty to the noncarbon-climate response. To quantify simulated carbon cycle feedbacks satisfactorily, a radiatively coupled experiment is needed, in addition to the fully coupled and biogeochemically coupled experiments, which are referred to as coupled and uncoupled in C4MIP. The concentration-carbon and climate-carbon feedbacks do not combine pararly, and the concentration-carbon feedback is dependent on scenario and time.

Gr200 Graham, I. and Lambin, X., 2002. The impact of weasel predation on cyclic field-vole survival: the specialist predator hypothesis contradicted. J. Anim. Ecol., 71(6): 946-956.    Gr200.pdf      

Abstract: 1. The delayed density-dependent predation of specialists such as weasels (Mustela nivalis L.) may result in cycles in the abundance of their prey. We estimated the demographic impact of weasel predation on field-vole (Microtus agrestis L.) survival using capture-recapture data from a large-scale, replicated predator-manipulation experiment conducted in six unfenced populations in Kielder Forest, northern England. The density of weasels was experimentally reduced through continuous live-trapping in the three removal populations. Field-vole survival was compared between paired removal and control populations during the increase, peak and decpar phases of a vole population cycle. Apparent survival and recapture probabilities were estimated using open population Cormack-Jolly Seber models. 2. Field-vole survival varied extensively both spatially between populations and temporally, being highest in the late autumn and over winter and lowest each year in spring and early summer. Patterns of variation in male and female survival were similar between populations over time, but there was independent spatial and temporal variation between adults and juveniles. Variation in weasel abundance explained 18\% of this independent spatial and temporal variation between adult and juvenile field-vole survival. 3. The average increase in annual vole survival resulting from weasel removal over the 2-year period was 27\% and 25\% for adult male and female field voles, respectively. Decreased weasel abundance increased adult field-vole survival. Adult-vole survival in the absence of weasels was predicted to be approximately 8\% higher than in the presence of one weasel per 4-5 ha. Surprisingly, weasel removal resulted in lowered juvenile field-vole survival, possibly reflecting increased emigration or mortality due to infanticide. A simple two age-class demographic model indicated that the decrease in juvenile survival in response to reduced weasel predation pressure did not fully compensate for the increase in adult survival. 4. As weasel numbers fluctuated seasonally, with highest weasel densities occurring in late summer and autumn and little spring to spring variation, the impact of weasel removal on field-vole survival was greatest during the breeding season. However, vole population-growth rates were unrelated to adult survival at that time and correspondingly no divergence was observed between the trajectories of control and removal vole populations even when weasel numbers were greatest in control sites. In contrast, vole population-growth rates were closely correlated with survival during the non-breeding season. Nevertheless all control and removal populations experienced a cyclic decpar in winter 1999-2000 in spite of the increased adult survival in experimental treatments. 5. We conclude that the impact of weasel predation on field-vole survival was neither sufficient nor necessary to initiate and drive the cyclic decpar of field-vole populations in Kielder Forest.

Gr202 Gray, D. R., 2008. The relationship between climate and outbreak characteristics of the spruce budworm in eastern Canada. Clim. Chang., 87(3-4): 361-383.    Gr202.pdf      

Abstract: The relationship between outbreak characteristics of the spruce budworm and the combination of climate, forest composition, and spatial location was examined in eastern Canada by the method of constrained ordination. Approximately 54% of the spatial variability in outbreak pattern, as described by a matrix of four outbreak characteristics, was explained by the spatial pattern of the climate (a matrix of six variables), forest composition (a matrix of seven variables), and spatial location (a matrix of two variables). The relationships between outbreak variables and climate variables were highlighted, and future outbreak characteristics of the spruce budworm were projected using simulations of a global circulation model for the period 2081-2100 where CO2 concentrations reach a maximum of approximately 550 ppm. Future outbreaks are predicted to be an average of approximately 6 years longer with an average of 15% greater defoliation. The methodology is described and the potential effects of climate change on landscape-scale outbreaks of the insect are discussed.

Gr203 Gray, D. R., 2008. The relationship between climate and outbreak characteristics of the spruce budworm in eastern Canada (vol 87, pg 361, 2008). Clim. Chang., 89(3-4): 447-449.    Gr203.pdf      

Gr204 Gray, D. R. and MacKinnon, W. E., 2006. Outbreak patterns of the spruce budworm and their impacts in Canada. For. Chron., 82(4): 550-561.    Gr204.pdf      

Abstract: Historical records (1941-1998) of spruce budworm defoliation in Canada were analyzed to estimate variability in the spatial and temporal patterns of defoliation, and to determine 27 representative patterns that adequately describe the spatial and temporal variability in defoliation. Spatially referenced estimates of growth loss and mortality resulting from an outbreak of spruce budworm were obtained by subjecting a national forest inventory to the spatially defined representative patterns of defoliation. The use of these estimates in determining the status of Canada's forests as a carbon source or sink is discussed.

Gy001 Gyalistras, D. and von Storch, H. and Fischlin, A. and Beniston, M., 1994. Linking GCM-simulated climatic changes to ecosystem models: case studies of statistical downscaling in the Alps. Clim. Res., 4(3): 167-189.    Gy001.pdf      

Abstract: According to the requirements of various ecosystem models, at each location 17 seasonal statistics related to daily temperatures, precipitation, sunshine duration, air humidity and wind speed were considered. Year-to-year variations of the local variables were linked by means of Canonical Correlation Analysis to simultaneous anomalies in the North Atlantic/European sea-level pressure and near-surface temperature fields. The analysis was performed for the period 1901 to 1940, separately for each season and location. In all cases, physically plausible statistical models were found which quantified the local effects of changes in major circulation patterns, such as the strength of westerly flow in winter and of large-scale subsidence in summer. The established statistical relationships were applied to anomaly fields as simulated by the Hamburg fully coupled atmospheric/oceanic ECHAM1/LSG GCM under increasing atmospheric greenhouse gas concentrations. The procedure yields time-dependent, internally consistent, and regionally strongly differentiated climatic change estimates for several important ecosystem inputs, at a spatial resolution far above the resolution of present GCMs.

Gy008 Gyalistras, D. and Fischlin, A., 1999. Towards a general method to construct regional climatic scenarios for model-based impacts assessments. Petermanns geogr. Mitt., 143(4): 251-264.    Gy008.pdf      

Abstract: Studies that use simulation models to assess possible regional impacts of climatic change have very diverse and demanding requirements for climatic input data. This paper presents a general method to construct climatic scenarios for such studies. It was developed in the context of several case studies dealing with possible climatic impacts on forest succession, grasslands, and snowpack/run-off in the European Alps. The following set of requirements was identified from the case studies and other, independently formulated scenario needs: The method should provide physically consistent, spatially and temporally extended scenarios at a high spatial and temporal resolution, be based upon a statistically accurate description of local weather and climate, and be robust, flexible, formally defined, and efficient. Based on our case studies and an evaluation of existing methods we derived the following general procedure: (1) Describe weather at the locations of interest as a stochastic process; (2) Estimate the process/climatic parameters for present climate from measurements; if no measurements are available, use a spatial interpolation procedure to estimate the parameters from nearby climatological stations; (3) Apply statistical downscaling to the output of a climate model to estimate time-dependent changes in selected climatic parameters; (4) Use the results from downscaling to adjust the parameters of the stochastic process, and generate weather sequences by means of stochastic simulation. The paper describes the current implementation of the individual components of the method (downscaling, stochastic weather generation, interpolation) and their combination within an overall framework for scenario construction. The proposed method is then compared to alternative approaches and discussed in light of our case studies. It is concluded that the method satisfies most of the above formulated requirements and thus provides a generally useful technique for model-based impact assessments. A main limitation presents the extensive use of statistical-descriptive models, which may not necessarily hold under a future climate. However, the proposed method supports extensive sensitivity studies, and thanks to its modular structure enhancements of the individual components can be easily incorporated as soon as they become available.

Ha387 Hayes, D. J. and McGuire, A. D. and Kicklighter, D. W. and Gurney, K. R. and Burnside, T. J. and Melillo, J. M., 2011. Is the northern high-latitude land-based CO2 sink weakening?. Glob. Biogeochem. Cycles, 25: GB3018.    Ha387.pdf      

Abstract: [1] Studies indicate that, historically, terrestrial ecosystems of the northern high-latitude region may have been responsible for up to 60\% of the global net land-based sink for atmospheric CO2. However, these regions have recently experienced remarkable modification of the major driving forces of the carbon cycle, including surface air temperature warming that is significantly greater than the global average and associated increases in the frequency and severity of disturbances. Whether Arctic tundra and boreal forest ecosystems will continue to sequester atmospheric CO2 in the face of these dramatic changes is unknown. Here we show the results of model simulations that estimate a 41 Tg C yr(-1) sink in the boreal land regions from 1997 to 2006, which represents a 73\% reduction in the strength of the sink estimated for previous decades in the late 20th century. Our results suggest that CO2 uptake by the region in previous decades may not be as strong as previously estimated. The recent decpar in sink strength is the combined result of (1) weakening sinks due to warming-induced increases in soil organic matter decomposition and (2) strengthening sources from pyrogenic CO2 emissions as a result of the substantial area of boreal forest burned in wildfires across the region in recent years. Such changes create positive feedbacks to the climate system that accelerate global warming, putting further pressure on emission reductions to achieve atmospheric stabilization targets.

He154 Heavilin, J. and Powell, J. and Logan, J. A., 2007. Dynamics of mountain pine beetle outbreaks. In: Johnson, E. A. and Miyanishi, K. (eds.), Plant Disturbance Ecology. Academic Press, Burlington, 527-553pp.    He154.pdf      

Abstract: Native forest insects are the greatest forces of change in forest ecosystems of North America. In aggregate, insect disturbances affect an area that is almost 45 times as great as that affected by fire, resulting in an economic impact nearly five times as great (Dale et al., 2001). Of these natural agents of ecosystem disturbance and change, the bark beetles are the most obvious in their impact, and of these, the mountain pine beetle (Dendroctonus pon- derosae Hopkins) has the greatest economic importance in the forests of western North America (Samman and Logan, 2000). The primary reason for this impact is that the mountain pine beetle is one of a handful of bark beetles that are true predators in that they must kill their host to success- fully reproduce, and they often do so in truly spectacular numbers.

Hi098 Hibbard, K. and Janetos, A. and van Vuuren, D. P. and Pongratz, J. and Rose, S. K. and Betts, R. and Herold, M. and Feddema, J. J., 2010. Research priorities in land use and land-cover change for the Earth system and integrated assessment modelling. Int. J. Climatol., 30(13): 2118-2128.    Hi098.pdf      

Abstract: This special issue has highlighted recent and innovative methods and results that integrate observations and modelling analyses of regional to global aspect of biophysical and biogeochemical interactions of land-cover change with the climate system. Both the Earth System and the Integrated Assessment modeling communities recognize the importance of an accurate representation of land use and land-cover change to understand and quantify the interactions and feedbacks with the climate and socio-economic systems, respectively. To date, cooperation between these communities has been limited. Based on common interests, this work discusses research priorities in representing land use and land-cover change for improved collaboration across modelling, observing and measurement communities. Major research topics in land use and land-cover change are those that help us better understand (1) the interaction of land use and land cover with the climate system (e.g. carbon cycle feedbacks), (2) the provision of goods and ecosystem services by terrestrial (natural and anthropogenic) land-cover types (e.g. food production), (3) land use and management decisions and (4) opportunities and limitations for managing climate change (for both mitigation and adaptation strategies). Copyright (C) 2010 Royal Meteorological Society and Crown Copyright.

Hi099 Hirschi, M. and Stoeckli, S. and Dubrovsky, M. and Spirig, C. and Calanca, P. and Rotach, M. W. and Fischer, A. M. and Duffy, B. and Samietz, J., 2012. Downscaling climate change scenarios for apple pest and disease modeling in Switzerland. Earth Syst. Dyn., 3(1): 33-47.    Hi099.pdf      

Abstract: As a consequence of current and projected climate change in temperate regions of Europe, agricultural pests and diseases are expected to occur more frequently and possibly to extend to previously non-affected regions. Given their economic and ecological relevance, detailed forecasting tools for various pests and diseases have been developed, which model their phenology, depending on actual weather conditions, and suggest management decisions on that basis. Assessing the future risk of pest-related damages requires future weather data at high temporal and spatial resolution. Here, we use a combined stochastic weather generator and re-sampling procedure for producing site-specific hourly weather series representing present and future (1980–2009 and 2045–2074 time periods) climate conditions in Switzerland. The climate change scenarios originate from the ENSEMBLES multi-model projections and provide probabilistic information on future regional changes in temperature and precipitation. Hourly weather series are produced by first generating daily weather data for these climate scenarios and then using a nearest neighbor re-sampling approach for creating realistic diurnal cycles. These hourly weather series are then used for modeling the impact of climate change on important life phases of the codling moth and on the number of predicted infection days of fire blight. Codling moth (Cydia pomonella) and fire blight (Erwinia amylovora) are two major pest and disease threats to apple, one of the most important commercial and rural crops across Europe. Results for the codling moth indicate a shift in the occurrence and duration of life phases relevant for pest control. In southern Switzerland, a 3rd generation per season occurs only very rarely under today's climate conditions but is projected to become normal in the 2045–2074 time period. While the potential risk for a 3rd generation is also significantly increasing in northern Switzerland (for most stations from roughly 1% on average today to over 60% in the future for the median climate change signal of the multi-model projections), the actual risk will critically depend on the pace of the adaptation of the codling moth with respect to the critical photoperiod. To control this additional generation, an intensification and prolongation of control measures (e.g. insecticides) will be required, implying an increasing risk of pesticide resistances. For fire blight, the projected changes in infection days are less certain due to uncertainties in the leaf wetness approximation and the simulation of the blooming period. Two compensating effects are projected, warmer temperatures favoring infections are balanced by a temperature-induced advancement of the blooming period, leading to no significant change in the number of infection days under future climate conditions for most stations.

Ho274 Hornfeldt, B. and Hipkiss, T. and Eklund, U., 2005. Fading out of vole and predator cycles?. Proc. R. Soc. Lond. Ser. B Biol. Sci., 272(1576): 2045-2049.    Ho274.pdf      

Abstract: Northern voles and lemmings are famous for their spectacular multiannual population cycles with high amplitudes. Such cyclic vole populations in Scandinavia have shown an unexpected and marked long-term decpar in density since the early 1970s, particularly with a marked shift to lower spring densities in the early 1980s. The vole decpar, mainly characterized by a strongly decreased rate of change in numbers over winter, is associated with an increased occurrence of mild and wet winters brought about by a recent change in the North Atlantic Oscillation. This has led to a decrease in winter stability and has shortened the period with protective snow cover, the latter considered as an important prerequisite for the occurrence of multiannual, high-amplitude cycles in vole populations. Although the vole decpar is predicted to be negative for predators' reproduction and abundance, empirical data showing this are rare. Here we show that the dynamics of a predator-prey system (Tengmalm's owl, Aegolius funereus, and voles), have in recent years gradually changed from 3-4 yr, high-amplitude cycles towards more or less annual fluctuations only.

Ho275 Hooper, D. U. and Chapin, F. S. and Ewel, J. J. and Hector, A. and Inchausti, P. and Lavorel, S. and Lawton, J. H. and Lodge, D. M. and Loreau, M. and Naeem, S. and Schmid, B. and Setala, H. and Symstad, A. J. and Vandermeer, J. and Wardle, D. A., 2005. Effects of biodiversity on ecosystem functioning: A consensus of current knowledge. Ecol. Monogr., 75(1): 3-35.    Ho275.pdf      

Abstract: Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls. The scientific community has come to a broad consensus on many aspects of the relationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are structured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain. Based on our review of the scientific literature, we are certain of the following conclusions: 1)Species' functional characteristics strongly influence ecosystem properties. Functional characteristics operate in a variety of contexts, including effects of dominant species, keystone species', ecological engineers, and interactions among species (e.g., competition, facilitation, mutualism, disease, and predation). Relative abundance alone is not always a good predictor of the ecosystem-level importance of a species, as even relatively rare species (e.g., a keystone predator) can strongly influence pathways of energy and material flows. 2) Alteration of biota in ecosystems via species invasions and extinctions caused by human activities has altered ecosystem goods and services in many well-documented cases. Many of these changes are difficult, expensive, or impossible to reverse or fix with technological solutions. 3) The effects of species loss or changes in composition, and the mechanisms by which the effects manifest themselves, can differ among ecosystem properties, ecosystem types, and pathways of potential community change. 4) Some ecosystem properties are initially insensitive to species loss because (a) ecosystems may have multiple species that carry out similar functional roles, (b) some species may contribute relatively little to ecosystem properties, or (c) properties may be primarily controlled by abiotic environmental conditions. 5) More species are needed to insure a stable supply of ecosystem goods and services as spatial and temporal variability increases, which typically occurs as longer time periods and larger areas are considered. We have high confidence in the following conclusions: 1) Certain combinations of species are complementary in their patterns of resource use and can increase average rates of productivity and nutrient retention. At the same time, environmental conditions can influence the importance of complementarity in structuring communities. Identification of which and how many species act in a complementary way in complex communities is just beginning. 2) Susceptibility to invasion by exotic species is strongly influenced by species composition and, under similar environmental conditions, generally decreases with increasing species richness. However, several other factors, such as propagule pressure, disturbance regime, and resource availability also strongly influence invasion success and often override effects of species richness in comparisons across different sites or ecosystems. 3) Having a range of species that respond differently to different environmental perturbations can stabilize ecosystem process rates in response to disturbances and variation in abiotic conditions. Using practices that maintain a diversity of organisms of different functional effect and functional response types will help preserve a range of management options. Uncertainties remain and further research is necessary in the following areas: 1) Further resolution of the relationships among taxonomic diversity, functional diversity, and community structure is important for identifying mechanisms of biodiversity effects. 2) Multiple trophic levels are common to ecosystems but have been understudied in biodiversity/ecosystem functioning research. The response of ecosystem properties to varying composition and diversity of consumer organisms is much more complex than responses seen in experiments that vary only the diversity of primary producers. 3) Theoretical work on stability has outpaced experimental, work, especially field research. We need long-term experiments to be able to assess temporal stability, as well as experimental perturbations to assess response to and recovery from a variety of disturbances. Design and analysis of such experiments must account for several factors that covary with species diversity. 4) Because biodiversity both responds to and influences ecosystem properties, understanding the feedbacks involved is necessary to integrate results from experimental communities with patterns seen at broader scales. Likely patterns of extinction and invasion need to be linked to different drivers of global change, the forces that structure communities, and controls on ecosystem properties for the development of effective management and conservation strategies. 5) This paper focuses primarily on terrestrial systems, with some coverage of freshwater systems, because that is where most empirical and theoretical study has focused. While the fundamental principles described here should apply to marine systems, further study of that realm is necessary. Despite some uncertainties about the mechanisms and circumstances under which diversity influences ecosystem properties, incorporating diversity effects into policy and management is essential, especially in making decisions involving large temporal and spatial scales. Sacrificing those aspects of ecosystems that are difficult or impossible to reconstruct, such as diversity, simply because we are not yet certain about the extent and mechanisms by which they affect ecosystem properties, will restrict future management options even further. It is incumbent upon ecologists to communicate this need, and the values that can derive from such a perspective, to those charged with economic and policy decision-making.

Ho276 Hofstetter, R. W. and Dempsey, T. D. and Klepzig, K. D. and Ayres, M. P., 2007. Temperature-dependent effects on mutualistic, antagonistic, and commensalistic interactions among insects, fungi and mites. Community ecology, 8(1): 47-56.    Ho276.pdf      

Abstract: The relative abundance and nature of associations between symbiotic species can be affected by abiotic conditions with consequences for population dynamics. We investigated the effects of temperature on the community of mites and fungi associated with the southern pine beetle, Dendroctonus frontalis, an important pest of pine forests in the southern United States. First, we determined whether the growth rates of mutualistic and antagonistic fungi associated with D. frontalis differed in their responses to temperature. Second, we tested the effects of temperature on the abundance of, and interactions among, fungi, mites and beetles within D. frontalis-infested trees. Fungi differed in their growth responses to temperature, resulting in changes in fungal-beetle associations. Mite species associated with D. frontalis also differed in their responses to temperature, resulting in different mite communities associated with bark beetle progeny. The effects of temperature on beetle reproduction could not be assessed because of high wood borer density, but inter-relations among surviving beetles, mites and fungi were altered by temperature. Results support the hypothesis that temperature can produce direct and indirect effects on the web of mutualistic and antagonistic relationships within the community of D. frontalis and their symbiotic mites and fungi.

Ho287 Hodgson, J. and Wilson, P. and Hunt, R. and Grime, J. and Thompson, K., 1999. Allocating C-S-R plant functional types: a soft approach to a hard problem. OIKOS, 85(2): 282-294.    Ho287.pdf    Ho287_S.pdf      

Abstract: A long-term research programme, conducted mainly in northern England, has involved held surveys (1965-77). laboratory screening (1974-96), monitoring of permanent plots (1958 to date) and manipulative experiments (1987 to date). The so-called C-S-R classification of plant functional types developed from all this activity. Patterns of covariation among the traits used in the classification have recently been validated in this journal. The C-S-R classification appears to be applicable to vegetation in general. It thus has considerable potential for interpreting and predicting vegetation and ecosystem properties on a world-wide scale. However, to realize this potential we need to develop simplified procedures to extrapolate the C-S-R system to the many species which have not been the subject of previous ecological investigation. Here we describe a rapid method for attribution of C-S-R type and we test its accuracy in Britain by comparing it with an independent classification based upon more laborious procedures. The new method allocates a functional type to an unknown herbaceous subject using few, simple predictor variables. We have developed spreadsheets to perform all of the necessary calculations. These may be downloaded from the UCPE website at http://www.shef.ac.uk/uni/academic/N-Q/ nuocpe, or obtained by direct application to the E-mail address ucpe@sheffield.ac.uk.

Hu050 Hunter, M. D. and Price, P. W., 2000. Detecting cycles and delayed density dependence: a reply to Turchin and Berryman. Ecol. Entomol., 25(1): 122-124.    Hu050.pdf      
Hu051 Hunter, M. D. and Price, P. W., 1998. Cycles in insect populations: delayed density dependence or exogenous driving variables?. Ecol. Entomol., 23(2): 216-222.    Hu051.pdf      

Abstract: Delayed density dependence, and the cycles in insect populations that it can generate, are often investigated using time-series analysis. Recently, several authors have raised concerns about the validity of using time-series analysis to detect density dependence. One particular concern is the suggestion that exogenous driving variables, such as cyclic weather patterns, can lead to the spurious detection of density dependence in natural populations. Using non-biological data (the electricity bills of one of the authors), we show how easy it is to be misled by the results of time-series analysis. We then present 16 years' data on the gall-forming sawfly, Euura lasiolepis (Hymenoptera: Tenthredinidae), and show that cycles in weather, specifically winter precipitation, lead to the spurious detection of density dependence in time-series analysis. We conclude that time-series analysis cannot stand alone as a method for inferring the action of density dependence, and urge further investigation of the effects of apparent cycles in abiotic forces on insect populations.

Im015 Ims, R. A. and Fuglei, E., 2005. Trophic interaction cycles in tundra ecosystems and the impact of climate change. Bioscience, 55(4): 311-322.    Im015.pdf      

Abstract: While population cycles are geographically widespread, it is on arctic tundra that such cycles appear to be most influential for the functioning of the whole ecosystem. We give an overview of tundra species that exhibit population cycles and describe what are currently, believed to be the causal mechanisms. Population cycles most likely originate from trophic interactions within the plant- based tundra food web, where lemmings, either as prey for carnivores or as consumers of plants, play the key role. The predominance of trophic interaction cycles at northern latitudes is ultimately related to climate, and such cycles should therefore be vulnerable to climate change. Recent evidence indicates that changes have already taken place in the dynamics of some key herbivores and their predators, consistent with the expected impacts of climate change. There is a strong need for large-scale integrated monitoring and research efforts to further document such changes and their ecosystem consequences.

Im018 Ims, R. A. and Henden, J.-A. and Killengreen, S. T., 2008. Collapsing population cycles. Trends Ecol. Evol., 23(2): 79-86.    Im018.pdf      

Abstract: During the past two decades population cycles in voles, grouse and insects have been fading out in Europe. Here, we discuss the cause and implication of these changes. Several pars of evidence now point to climate forcing as the general underlying cause. However, how climate interacts with demography to induce regime shifts in population dynamics is likely to differ among species and ecosystems. Herbivores with high-amplitude population cycles, such as voles, lemmings, snowshoe hares and forest Lepidoptera, form the heart of terrestrial food web dynamics. Thus, collapses of these cycles are also expected to imply collapses of important ecosystem functions, such as the pulsed flows of resources and disturbances.

Im019 Ims, R. A. and Yoccoz, N. G. and Killengreen, S. T., 2011. Determinants of lemming outbreaks. Proc. Natl. Acad. Sci. USA, 108(5): 1970-1974.    Im019.pdf      

Abstract: Population outbreaks in tundra rodents have intrigued scientists for a century as a result of their spectacular appearances and their general lessons in ecology. One outstanding question that has led to competing hypotheses is why sympatric lemmings and voles differ in regularity and shape of their outbreaks. Lemming outbreaks may be lost for decades while vole populations maintain regular population cycles. Moreover, when lemming populations eventually irrupt, they do so more steeply than the vole populations. Norwegian lemmings exhibited a large-scale outbreak synchronously with gray-sided voles in Finnmark, northern Fennoscandia, during 2006 to 2007 for the first time in two decades. Analyses of spatial variability of this outbreak across altitudinal gradients allowed us to identify determinants of the contrasting lemming and vole dynamics. The steeper lemming outbreak trajectories were caused by breeding and population growth during winter, when nonbreeding vole populations consistently decpard. The differently shaped lemming and vole outbreaks appear to result from a particular demographic tactic of lemmings that evolved as an adaptation to the long and cold Arctic-Alpine winters. The lemming outbreak amplitude increased with altitude and vole density, indicating that lemming outbreaks are jointly facilitated by low temperatures and apparent mutualism with voles mediated by shared predators. High sensitivity to variation in climate and predation is likely to be the reasons why lemmings have more erratic population dynamics than sympatric voles. The combination of continued climatic warming and dampened vole cycles is expected to further decrease the frequency, amplitude, and geographic range of lemming outbreaks in tundra ecosystems.

Is009 Isenegger, D. and Price, B. and Wu, Y. and Fischlin, A. and Frei, U. and Weibel, R. and Allgower, B., 2005. IPODLAS - A software architecture for coupling temporal simulation systems, VR, and GIS. Photogramm. Remote Sens., 60(1): 34-47.    Is009.pdf      

Abstract: Environmental processes often vary in space and time and act over several scales. Current software applications dealing with aspects of these processes emphasize properties specific to their domain and tend to neglect other issues. For example, GIS prefers a static view and generally lacks the representation of dynamics, temporal simulation systems emphasize the temporal component but ignore space to a great extent, and virtual reality tends to ``forget'' the underlying data and models. In order to remedy this situation we present an approach that aims to bring together the three domains; temporal simulation systems, GIS, and virtual reality, and to foster the integration of particular functionalities. This paper concentrates on concepts and requirements for the development of a suitable software architecture using case studies and use cases seen from a GIS-based perspective. (C) 2005 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Published by Elsevier B.V. All rights reserved.

Ja106 Jang, S. R. and Yu, J., 2009. Models of plant quality and larch budmoth interaction. Nonlinear Anal. Theory, methods & appl., 71(12): e1904-e1908.    Ja106.pdf      
Ja115 Janis, C. and Damuth, J. and Theodor, J., 2000. Miocene ungulates and terrestrial primary productivity: where have all the browsers gone?. Proc. Natl. Acad. Sci. USA, 97(14): 7899-7904.    Ja115.pdf      

Abstract: Progressive changes are observed in both the composition of mammal faunas and vegetation during the Miocene epoch [24-5 mega-annum (Ma)], These changes are usually interpreted as a response to climatic changes. In the traditional view, forests or woodlands gradually gave way to more open habitats, with grazing (grass-eating) ungulate (hoofed) mammal species replacing the browsing (leafy-vegetation-eating) species as grasslands expanded. However, data from fossil assemblages in the Great Plains region of North America show that this faunal change was not a one-for-one replacement of browsers by grazers, as usually thought. Typical late early Miocene (17 Ma) fossil communities included extraordinarily high numbers of browsing ungulate species, comprising a fauna that cannot be directly analogized with any present-day community. Both maximum species richness of all ungulates and the proportion of browsers decpard steadily in ungulate communities through the middle Miocene, to levels comparable to those of the present by the late Miocene. The resulting dramatic, cumulative loss of browsing species constitutes one of the strongest faunal signals of the late Tertiary (but was not a single ``event''). We suggest that the early Miocene browser-rich communities may reflect higher levels of primary productivity in Miocene vegetation, compared with equivalent present-day vegetation types. The observed decpar in species richness may represent a gradual decpar in primary productivity, which would be consistent with one current hypothesis of a mid-Miocene decrease in atmospheric CO2 concentrations from higher mid-Cenozoic values.

Ja120 James, P. M. A. and Fleming, R. A. and Fortin, M.-J., 2010. Identifying significant scale-specific spatial boundaries using wavelets and null models: spruce budworm defoliation in Ontario, Canada as a case study. Landscape Ecol., 25(6): 873-887.    Ja120.pdf      

Abstract: We combine wavelet analysis and multiple null models to identify significant spatial scales of pattern and spatial boundaries in historical spruce budworm defoliation in Ontario, Canada. Previous analyses of budworm defoliation in Ontario over the last two outbreaks have suggested three distinct zones of defoliation. We asked the following three questions: (1) is there statistical support for the existence of these three zones? (2) Are the locations of these boundaries consistent between outbreak periods? And (3) how does boundary identification depend on the spatial null model used? Defoliation data for the two outbreak periods (1941-1965 and 1966-2001), and the combined period (1941-2001) were analyzed using a 1D continuous wavelet transform. Boundaries were identified through comparison of wavelet power spectra of each outbreak period to reference distributions based on three different spatial null models: (1) a complete spatial randomness model, (2) an autoregressive model, and (3) a Gaussian random field model. The Gaussian random field model identified coarser scales of pattern than the autoregressive model. Locally, the Gaussian random field model found significant boundaries similar to those previously described, whereas the autoregressive model only did so for the first outbreak. These results indicate that the coarse scale spatial factors that influenced defoliation were more consistent between outbreaks relative to fine scale factors, and that previously described boundaries were strongly driven by the first outbreak. Wavelet analysis combined with spatial null models provides a powerful tool for identifying non-arbitrary scales of structure and significant spatial boundaries in non-stationary ecological data.

Je027 Jepsen, J. U. and Hagen, S. B. and Ims, R. A. and Yoccoz, N. G., 2008. Climate change and outbreaks of the geometrids Operophtera brumata and Epirrita autumnata in subarctic birch forest: evidence of a recent outbreak range expansion. J. Anim. Ecol., 77(2): 257-264.    Je027.pdf      

Abstract: 1. Range expansions mediated by recent climate warming have been documented for many insect species, including some important forest pests. However, whether climate change also influences the eruptive dynamics of forest pest insects, and hence the ecological and economical consequences of outbreaks, is largely unresolved. 2. Using historical outbreak records covering more than a century, we document recent outbreak range expansions of two species of cyclic geometrid moth, Operophtera brumata Bkh. (winter moth) and Epirrita autumnata L. (autumnal moth), in subarctic birch forest of northern Fennoscandia. The two species differ with respect to cold tolerance, and show strikingly different patterns in their recent outbreak range expansion. 3. We show that, during the past 15-20 years, the less cold-tolerant species O. brumata has experienced a pronounced north-eastern expansion into areas previously dominated by E. autumnata outbreaks. Epirrita autumnata, on the other hand, has expanded the region in which it exhibits regular outbreaks into the coldest, most continental areas. Our findings support the suggestion that recent climate warming in the region is the most parsimonious explanation for the observed patterns. 4. The presence of O. brumata outbreaks in regions previously affected solely by E. autumnata outbreaks is likely to increase the effective duration of local outbreaks, and hence have profound implications for the subarctic birch forest ecosystem.

Jo115 Jones, P. D. and Briffa, K. R. and Osborn, T. J. and Lough, J. M. and van Ommen, T. D. and Vinther, B. M. and Lutherbacher, J. and Wahl, E. R. and Zwiers, F. W. and Mann, M. E. and Schmidt, G. A. and Ammann, C. M. and Buckley, B. M. and Cobb, K. M. and Esper, J. and Goosse, H. and Graham, N. and Jansen, E. and Kiefer, T. and Kull, C. and Kuettel, M. and Mosley-Thompson, E. and Overpeck, J. T. and Riedwyl, N. and Schulz, M. and Tudhope, A. W. and Villalba, R. and Wanner, H. and Wolff, E. and Xoplaki, E., 2009. High-resolution palaeoclimatology of the last millennium: a review of current status and future prospects. Holocene, 19(1): 3-49.    Jo115.pdf      

Abstract: This review of late-Holocene palaeoclimatology represents the results from a PAGES/CLIVAR Intersection Panel meeting that took place in June 2006. The review is in three parts: the principal high-resolution proxy discippars (trees, corals, ice cores and documentary evidence), emphasizing current issues in their e for climate reconstruction; the various approaches that have been adopted to combine multiple climate us proxy records to provide estimates of past annual-to-decadal timescale Northern Hemisphere surface temperatures and other climate variables, such as large-scale circulation indices; and the forcing histories used in climate model simulations of the past millennium. We discuss the need to develop a framework through which current and new approaches to interpreting these proxy data may be rigorously assessed using pseudo-proxies derived from climate model runs, where the 'answer' is known. The article concludes with a list of recommendations. First, more raw proxy data are required from the diverse discippars and from more locations, as well as replication, for all proxy sources, of the basic raw measurements to improve absolute dating, and to better distinguish the proxy climate signal from noise. Second, more effort is required to improve the understanding of what individual proxies respond to, supported by more site measurements and process studies. These activities should also be mindful of the correlation structure of instrumental data, indicating which adjacent proxy records ought to be in agreement and which not. Third, large-scale climate reconstructions should be attempted using a wide variety of techniques, emphasizing those for which quantified errors can be estimated at specified timescales. Fourth, a greater use of climate model simulations is needed to guide the choice of reconstruction techniques (the pseudo-proxy concept) and possibly help determine where, given limited resources, future sampling should be concentrated.

Jo122 Johnson, D. M. and Büntgen, U. and Frank, D. C. and Kausrud, K. and Haynes, K. J. and Liebhold, A. M. and Esper, J. and Stenseth, N. C., 2010. Climatic warming disrupts recurrent Alpine insect outbreaks. PNAS, 107(47): 20576-20581.    Jo122.pdf    Jo122_S.pdf      

Abstract: Climate change has been identified as a causal factor for diverse ecological changes worldwide. Warming trends over the last couple of decades have coincided with the collapse of long-term population cycles in a broad range of taxa, although causal mechanisms are not well-understood. Larch budmoth (LBM) population dynamics across the European Alps, a classic example of regular outbreaks, inexplicably changed sometime during the 1980s after 1,200 y of nearly uninterrupted periodic outbreak cycles. Herein, analysis of perhaps the most extensive spatiotemporal dataset of population dynamics and reconstructed Alpine-wide LBM defoliation records reveals elevational shifts in LBM outbreak epicenters that coincide with temperature fluctuations over two centuries. A population model supports the hypothesis that temperature-mediated shifting of the optimal elevation for LBM population growth is the mechanism for elevational epicenter changes. Increases in the optimal elevation for population growth over the warming period of the last century to near the distributional limit of host larch likely dampened population cycles, thereby causing the collapse of a millennium-long outbreak cycle. The threshold-like change in LBM outbreak pattern highlights how interacting species with differential response rates to climate change can result in dramatic ecological changes.

Jo124 Johnson, E. A. and Miyanishi, K., 2007. Disturbance and succession. In: Johnson, E. A. and Miyanishi, K. (eds.), Plant Disturbance Ecology. Academic Press, Introduction, Burlington, 1-14pp.    Jo124.pdf      

Abstract: Natural or anthropogenic disturbance was traditionally viewed as an event that initiated primary or secondary succession, and succession explained the development of vegetation in the absence of disturbance. Thus, the concepts of disturbance and succession are inextricably linked in plant ecology.

Ju016 Jungclaus, J. H. and Lorenz, S. J. and Timmreck, C. and Reick, C. H. and Brovkin, V. and Six, K. and Segschneider, J. and Giorgetta, M. A. and Crowley, T. J. and Pongratz, J. and Krivova, N. A. and Vieira, L. E. and Solanki, S. K. and Klocke, D. and Botzet, M. and Esch, M. and Gayler, V. and Haak, H. and Raddatz, T. J. and Roeckner, E. and Schnur, R. and Widmann, H. and Claussen, M. and Stevens, B. and Marotzke, J., 2010. Climate and carbon-cycle variability over the last millennium. Clim. Past, 6(5): 723-737.    Ju016.pdf      

Abstract: A long-standing task in climate research has been to distinguish between anthropogenic climate change and natural climate variability. A prerequisite for fulfilling this task is the understanding of the relative roles of external drivers and internal variability of climate and the carbon cycle. Here, we present the first ensemble simulations over the last 1200 years with a comprehensive Earth system model including a fully interactive carbon cycle. Applying up-to-date reconstructions of external forcing including the recent low-amplitude estimates of solar variations, the ensemble simulations reproduce temperature evolutions consistent with the range of reconstructions. The 20th-century warming trend stands out against all pre-industrial trends within the ensemble. Volcanic eruptions are necessary to explain variations in pre-industrial climate such as the Little Ice Age; yet only the strongest, repeated eruptions lead to cooling trends that differ significantly from the internal variability across all ensemble members. The simulated atmospheric CO2 concentrations exhibit a stable carbon cycle over the pre-industrial era with multi-centennial variations somewhat smaller than in the observational records. Early land-cover changes have modulated atmospheric CO2 concentrations only slightly. We provide a model-based quantification of the sensitivity (termed gamma) of the global carbon cycle to temperature for a variety of climate and forcing conditions. We diagnose a distinct dependence of gamma on the forcing strength and time-scales involved, thus providing a possible explanation for the systematic difference in the observational estimates for different segments of the last millennium.

Ka044 Karban, R. and Myers, J. H., 1989. Induced plant responses to herbivory. Annu. Rev. Ecol. Syst., 20: 331-348.    Ka044.pdf    Ka044_S.pdf   

Ka172 Kausrud, K. L. and Mysterud, A. and Steen, H. and Vik, J. O. and Ostbye, E. and Cazelles, B. and Framstad, E. and Eikeset, A. M. and Mysterud, I. and Solhoy, T. and Stenseth, N. C., 2008. Linking climate change to lemming cycles. Nature, 456(7218): 93-97.    Ka172.pdf      

Abstract: The population cycles of rodents at northern latitudes have puzzled people for centuries(1,2), and their impact is manifest throughout the alpine ecosystem(2,3). Climate change is known to be able to drive animal population dynamics between stable and cyclic phases(4,5), and has been suggested to cause the recent changes in cyclic dynamics of rodents and their predators(3,6-9). But although predator - rodent interactions are commonly argued to be the cause of the Fennoscandian rodent cycles(1,10-13), the role of the environment in the modulation of such dynamics is often poorly understood in natural systems(8,9,14). Hence, quantitative links between climate-driven processes and rodent dynamics have so far been lacking. Here we show that winter weather and snow conditions, together with density dependence in the net population growth rate, account for the observed population dynamics of the rodent community dominated by lemmings ( Lemmus lemmus) in an alpine Norwegian core habitat between 1970 and 1997, and predict the observed absence of rodent peak years after 1994. These local rodent dynamics are coherent with alpine bird dynamics both locally and over all of southern Norway, consistent with the influence of large- scale fluctuations in winter conditions. The relationship between commonly available meteorological data and snow conditions indicates that changes in temperature and humidity, and thus conditions in the subnivean space, seem to markedly affect the dynamics of alpine rodents and their linked groups. The pattern of less regular rodent peaks, and corresponding changes in the overall dynamics of the alpine ecosystem, thus seems likely to prevail over a growing area under projected climate change.

Ka173 Kaitaniemi, P. and Ruohomäki, K. and Tammaru, T. and Haukioja, E., 1999. Induced resistance of host tree foliage during and after a natural insect outbreak. J. Anim. Ecol., 68(2): 382-389.    Ka173.pdf      

Abstract: 1. Plant resistance against insect herbivores often increases after experimental damage to foliage, but few studies have obtained field estimates of the effect of induced resistance on insect populations during and after a natural insect outbreak. 2. This study measured the effect of quality of the host tree, mountain birch (Betula pubescens ssp. czerepanovii), on the periodically fluctuating folivore Epirrita autumnata (Lepidoptera, Geometridae) during peak and postpeak years of an outbreak in Finnish Lapland. Comparisons were made both within and between study sites to assess host plant quality, anti thereby the effect of delayed induced resistance (DIR). 3. In within-site comparisons, a set of experimental trees was defoliated by wild larvae in the peak year of the outbreak, whereas control trees were protected from defoliation by spraying with an insecticide. The effect of host plant quality was quantified in :ht following year bq measuring the pupal mass of E. autumnata larvae reared in enciosures on these trees. 4. In between-site comparisons, the sizes of pheromone-trapped males were measured at both outbreak and low density sites during the progress of the outbreak. The size of trapped males was subsequently used to estimate the corresponding fecundity of females at the same sites. 5. Pupal mass of E. autumnata reared on trees defoliated in the previous year was 0- 10\% lower than on those trees protected from defoliation by the insecticide. Field-collected adults indicated 3 similar pattern: they were smaller at outbreak sites than at low-density sites, and the size reached its minimum in the post-peak year. However the estimated loss of reproductive capacity of females resulting from DIR was too small to be: the sole explanation for the termination of the outbreak. 6. Whether the weak DIR response in this system was a characteristic of the 1990s outbreak alone ri mains unclear, because different terminating agents may be important for different individual outbreak peaks. During this outbreak, larval parasitism and developmental asynchrony between larvae and birch were probably more important reasons for population collapse than DIR.

Ka175 Kambatuku, J. R. and Cramer, M. D. and Ward, D., 2011. Savanna tree-grass competition is modified by substrate type and herbivory. J. Veg. Sci., 22(2): 225-237.    Ka175.pdf      

Abstract: Question Woody plant and grass interactions in savannas have frequently been studied from the perspective of the response of one growth form on the other but seldom evaluated as two-way interactions. What causes woody plant encroachment in semi-arid savannas and what are the competitive responses of tree seedlings and grasses on rocky and sandy substrates? Methods In this greenhouse study, we investigated the influence of substrate and grazing on responses to interspecific competition by tree seedlings and grasses. We measured competitive/facilitative responses on biomass and nutrient status of tree seedlings and grasses grown together. Results Interspecific competition suppressed growth of trees and grasses. Tree seedlings and uncut grass accumulated double the biomass when grown without competition relative to when they competed. Competitive responses varied on different substrates. Grass biomass on rocky substrate showed no response to tree competition, but appeared to be facilitated by trees on sandy substrate. Grass clipping resulted in higher tree seedling biomass on rocky substrate, but not on sandy substrate. There was a positive response of grass nutrient status to competition from tree seedlings. Conclusion Selective grass herbivory in the absence of browsing or suppression of shade-intolerant grasses by trees are commonly cited reasons behind bush encroachment in savannas. We show that grazing may confer a competitive advantage to tree seedlings and promote bush encroachment more readily on rocky substrates. This may be due to the imposed sharing of the soil depth niche on rocky substrates, whereas possible niche separation on sandy substrates minimizes the advantage conferred by reduced competition.

Ke013 Kettala, E. G., 1983. A cartographic history of spruce budworm defoliation from 1967 to 1981 in Eastern North America. Information report DPC-X-14, Canadian Forestry Service, Departement of Environment, Ottawa, Ontario, 8pp.
Ke094 Kendall, B. E. and Briggs, C. J. and Murdoch, W. W. and Turchin, P. and Ellner, S. P. and McCauley, E. and Nisbet, R. M. and Wood, S. N., 1999. Why do populations cycle? A synthesis of statistical and mechanistic modeling approaches. Ecology, 80(6): 1789-1805.    Ke094.pdf      

Abstract: Population cycles have long fascinated ecologists. Even in the most-studied populations, however, scientists continue to dispute the relative importance of various potential causes of the cycles, Over the past three decades, theoretical ecologists have cataloged a large number of mechanisms that are capable of generating cycles in population models. At the same time, statisticians have developed new techniques both for characterizing time series and for fitting population models to time-series data. Both disciplines are now sufficiently advanced that great gains in understanding can be made by synthesizing these complementary, and heretofore mostly independent, quantitative approaches. In this paper we demonstrate how to apply this synthesis to the problem of population cycles, using both long-term population time series and the often-rich observational and experimental data on the ecology of the species in question. We quantify hypotheses by writing mathematical models that embody the interactions and forces that might cause cycles. Some hypotheses can be rejected out of hand, as being unable to generate even qualitatively appropriate dynamics, We finish quantifying the remaining hypotheses by estimating parameters, both from independent experiments and from fitting the models to the time-series data using modern statistical techniques, Finally, we compare simulated time series generated by the models to the observed time series, using a variety of statistical descriptors, which we refer to collectively as ``probes.'' The model most similar to the data, as measured by these probes, is considered to be the most likely candidate to represent the mechanism underlying the population cycles. We illustrate this approach by analyzing one of Nicholson's blowfly populations, in which we know the ``true'' governing mechanism. Our analysis, which uses only a subset of the information available about the population, uncovers the correct answer, suggesting that this synthetic approach might be successfully applied to field populations as well.

Ke169 Kendall, B. and Ellner, S. and McCauley, E. and Wood, S. and Briggs, C. and Murdoch, W. and Turchin, P., 2005. Population cycles in the pine looper moth: dynamical tests of mechanistic hypotheses. Ecol. Monogr., 75(2): 259-276.    Ke169.pdf      

Abstract: The forest insect pest Bupalus piniarius (pine looper moth) is a classic example of a natural population cycle. As is typical for Populations that exhibit regular oscillations in density, there are several biological mechanisms that are hypothesized to be responsible for the cycles; but despite several decades of detailed study there has been no definite conclusion as to which mechanism is most important. We evaluated three hypotheses for which there was direct experimental evidence: (1) food quality (nutritional value of pine needles affected by defoliation); (2) parasitoids (trophic interactions with specialist parasitoids), and (3) maternal effects (maternal body size affects the performance of offspring). We reviewed the empirical evidence for each of these hypotheses and expressed each hypothesis in the form of a mechanistic dynamic model. We used a nonparar forecasting approach to fit each model to three long-term Population time series in Britain that exhibit some degree of regular cycling, and we used parametric bootstrap to evaluate the significance of differences between models in their goodness of fit to the data. The results differed among the three forests: at Culbin, the parasitoid and maternal effects models fit equally well; at Roseisle, the food quality and maternal effects models fit equally well; and at Tentsmuir, the parasitoid model fit best. However, the best-fit parasitism models required that the parasitism rate vary between nearly 0 and nearly 1 during a cycle, greatly exceeding the range of parasitism rates that have been observed in the field. In contrast, the required variation in the observable maternal quality variable (pupal mass) was within the range of empirical observations. Under mild constraints on the parasitism rate (though allowing a much wider range than has been measured in B. piniarius at any location), the fit of the parasitism model fell off dramatically. The maternal effects model then had uniformly strong support, outperforming the constrained parasitism model at all three sites and the food quality model at two; it performed slightly better than the food quality model at the remaining site. This represents the first system in which the maternal effects hypothesis for population cycles has been supported by both strong biological and dynamical evidence.

Ke184 Kelly, B. and Whiteley, A. and Tallmon, D., 2010. The arctic melting pot. Nature, 468(7326): 891-891.    Ke184.pdf    Ke184_S.pdf      

Abstract: Hybridization in polar species could hit biodiversity hard, say Brendan Kelly, Andrew Whiteley and David Tallmon.

Ke185 Kendall, B., 2001. Cycles, chaos, and noise in predator-prey dynamics. Chaos Soliton. Fract., 12(2): 321-332.    Ke185.pdf      

Abstract: In contrast to the single species models that were extensively studied in the 1970s and 1980s, predator-pray models give rise to long-period oscillations, and even systems with stable equilibria can display oscillatory transients with a regular frequency. Many fluctuating populations appear to be governed by such interactions. However, predator-prey models have been poorly studied with respect to the interaction of nonparar dynamics, noise, and system identification. I use simulated data from a simple host-parasitoid model to investigate these issues. The addition of even a modest amount of noise to a stable equilibrium produces enough structured variation to allow reasonably accurate parameter estimation. Despite the fact that more-or-less regular cycles are generated by adding noise to any of the classes of deterministic attractor (stable equilibrium, periodic and quasiperiodic orbits, and chaos), the underlying dynamics can usually be distinguished, especially with the aid of the mechanistic model. However, many of the time series can also be fit quite well by a wrong model, and the fitted wrong model usually misidentifies the underlying attractor. Only the chaotic time series convincingly rejected the wrong model in favor of the true one. Thus chaotic population dynamics offer the best chance for successfully identifying underlying regulatory mechanisms and attractors. (C) 2000 Elsevier Science Ltd. All rights reserved.

Ki177 Kielland, K. and Bryant, J., 1998. Moose herbivory in Taiga: effects on biogeochemistry and vegetation dynamics in primary succession. OIKOS, 82(2): 377-383.      

Abstract: Early successional processes in taiga forest ecosystems are believed to be primarily under abiotic controls, with biotic factors taking on greater importance later in the successional sequence. Here we report how moose (Alces alces L.), a dominant mammalian herbivore, exert major control over biogeochemical processes early in succession in the taiga of Alaska. Moose browsing affects soil chemistry and vegetation dynamics in ways that influence subsequent plant establishment and ultimately forest development. Browsing significantly changed soil organic matter pools, the composition of soil carbon fractions, and the stable isotope signature (delta(13)C and delta(15)N) of surface soils. These edaphic modifications were accompanied by changes in plant species composition that accelerate the successional trajectory. Thus, we contend that the rate of initial plant establishment and early forest succession in taiga is under significant control by mammalian herbivores.

Kl059 Kleinen, T. and Brovkin, V. and von Bloh, W. and Archer, D. and Munhoven, G., 2010. Holocene carbon cycle dynamics. Geophys. Res. Lett., 37: L02705.    Kl059.pdf      

Abstract: We are investigating the late Holocene rise in CO2 by performing four experiments with the climate-carbon-cycle model CLIMBER2-LPJ. Apart from the deep sea sediments, important carbon cycle processes considered are carbon uptake or release by the vegetation, carbon uptake by peatlands, and CO2 release due to shallow water sedimentation of CaCO3. Ice core data of atmospheric CO2 between 8 ka BP and preindustrial climate can only be reproduced if CO2 outgassing due to shallow water sedimentation of CaCO3 is considered. In this case the model displays an increase of nearly 20 ppmv CO2 between 8 ka BP and present day. Model configurations that do not contain this forcing show a slight decrease in atmospheric CO2. We can therefore explain the late Holocene rise in CO2 by invoking natural forcing factors only, and anthropogenic forcing is not required to understand preindustrial CO2 dynamics. Citation: Kleinen, T., V. Brovkin, W. von Bloh, D. Archer, and G. Munhoven (2010), Holocene carbon cycle dynamics, Geophys. Res. Lett., 37, L02705, doi: 10.1029/2009GL041391.

Kl060 Klemola, T. and Hanhimäki, S. and Ruohomäki, K. and Senn, J. and Tanhuanpää, M. and Kaitaniemi, P. and Ranta, H. and Haukioja, E., 2003. Performance of the cyclic autumnal moth, Epirrita autumnata, in relation to birch mast seeding. Oecologia, 135(3): 354-361.    Kl060.pdf      

Abstract: The mast depression hypothesis has been put forward to explain the 9- to 10-year population cycle of the autumnal moth (Epirrita autumnata; Lepidoptera: Geometridae) in northern Fennoscandia. We analysed long-term data from Finnish Lapland in order to evaluate the critical assumption of the mast depression hypothesis: that better individual performance of herbivores, followed by high annual growth rate of populations, occurs in the year following mast seeding of the host, the mountain birch (Betula pubescens ssp. czerepanovii). Since mast seeding has been suggested to occur at the expense of chemical defence against herbivores, we bioassayed the quality of birch leaves from the same trees by means of yearly growth trials with autumnal moth larvae. We also measured the size of wild adults as a determinant of potential fecundity of the species in different years. The relative growth rate of larvae was poorer in post-mast years compared to other years, rather than better as assumed by the hypothesis. Conversely, a slight indication of the increase in potential fecundity was observed due to the somewhat larger adult size in post-mast years. Population growth rate estimates, however, showed that the increase in fecundity would have to be much higher to facilitate population increase towards a cyclic peak with outbreak density. Accordingly, our two data sets do not support the assumption of a higher annual growth rate in autumnal moth populations subsequent to mast seeding of the host, thereby contradicting the predictions of the mast depression hypothesis. Temperatures, when indexed by the North Atlantic Oscillation and accumulated thermal sums, were observed to correlate with the abundance or rate of population change of the autumnal moth. The factors underlying the regular population cycles of the autumnal moth, however, remain unidentified. Overall, we suggest that the causal agents in cyclic insect population dynamics should be clarified by field experimentation, since trophic interactions are complex and are further modified by abiotic factors such as climate.

Kl061 Klemola, T. and Norrdahl, K. and Korpimäki, E., 2000. Do delayed effects of overgrazing explain population cycles in voles?. OIKOS, 90(3): 509-516.    Kl061.pdf      

Abstract: Theoretical models predict that delayed density-dependent processes with a time-lag of approximately nine months are sufficient to generate regular 3-5 year fluctuations in densities of northern small rodents. To examine whether this time-lag could be generated by plant-herbivore interactions, we studied delayed effects of overgrazed food plants on voles. We introduced field voles (Microtus agrestis) in four large predator-proof enclosures that had suffered heavy grazing during the preceding autumn and winter, and compared them with voles introduced to previously ungrazed control areas. We found no detrimental effects of previous grazing on population growth, reproduction or body condition of voles. Chemical analyses did not show consistent effects of grazing on nutritional components of common food plants (grasses). These results suggest that short-term population cycles of Microtus voles in grassland habitats are not primarily driven by delayed effects of plant-herbivore interactions.

Ko155 Korpimäki, E. and Brown, P. and Jacob, J. and Pech, R., 2004. The puzzles of population cycles and outbreaks of small mammals solved?. Bioscience, 54(12): 1071-1079.    Ko155.pdf      

Abstract: Well-known examples of high-amplitude, large-scalefluctuations of small-mammal populations include vole cycles in the boreal zone of Eurasia, lemming cycles in the high-arctic tundra of Eurasia and North America, snowshoe hare cycles in the boreal zone of North America, and outbreaks of house mice in southeastern Australia. We synthesize the recent knowledge of three key aspects of these animals' population cyles: (1) periodicity, amplitude, and spatiotemporal synchrony; (2) reproduction and survival; and (3) underlying mechanisms. Survival rather than reproductive rate appears to drive rates of population increase during these fluctuations. Food limitation may stop increases of cyclic vole, lemming, and hare poptulations, whereas the decpar from peak numbers is caused by predation mortality. In house mice, without coevolved predators, outbreaks may be driven by rainfall, food supply, and disease.

Ko159 Kocsis, M. and Hufnagel, L., 2011. Impacts of climate change on Lepidoptera species and communities. Appl. Ecol. Environ. Res., 9(1): 43-72.    Ko159.pdf      

Abstract: In this review, the impacts of climate change on Lepidoptera species and communities are summarized, regarding already registered changes in case of individual species and assemblies, and possible future effects. These include changes in abundance, distribution ranges (altitude above sea level, geographical distribution), phenology (earlier or later flying, number of generations per year). The paper also contains a short description of the observed impacts of single factors and conditions (temperature, atmospheric CO2 concentration, drought, predators and parasitoids, UV-B radiation) affecting the life of moths and butterflies, and recorded monitoring results of changes in the Lepidoptera communities of some observed areas. The review is closed with some theoretical considerations concerning the characteristics of ``winner'' species and also the features and conditions needed for a successful invasion, conquest of new territories.

Kr029 Krebs, C. J., 1996. Population cycles revisited. J. Mamm., 77(1): 8-24.    Kr029.pdf      

Abstract: Periodic fluctuations or cycles in populations of small mammals have been widely studied, but much controversy still exists about their causes. Cycles of voles and lemmings are produced by the integrated effects of intrinsic and extrinsic factors, and the problem is to define accurately how these interact. Spacing behavior is a key component of population regulation in voles and lemmings, and this is illustrated most dramatically by the fence effect. We do not know which mechanisms produce changes in social behavior. Phenotypic changes produced by maternal effects or stress are now believed most likely, but there has been too little work done on genetic effects on spacing and we know almost nothing about kin-related social behavior in voles and lemmings. Both predation and food supply may be the extrinsic factors involved in cyclic population dynamics. Single-factor experiments suggest that food shortage by itself does not seem to be a necessary factor for cycles nor does predation, but the interaction between food and predation could be a key variable in understanding how extrinsic factors affect cycles of voles. Cycles of snowshoe hares are caused by an interaction between predation and food supplies, possibly integrated through risk-sensitive foraging. Spacing behavior is not a component of cycles of hares because snowshoe hares differ from voles and lemmings in having no known form of spacing behavior that can produce social mortality. The short- term cycle of voles and lemmings thus seems to have a different explanation from the long-term cycle of snowshoe hares. In some places, lemmings may be locked in a predator-pit at low density. Experimental exclusion of predators improved survival of adults in a population of collared lemmings, but was not sufficient to allow them to escape the predator-pit because of losses of juveniles. Whether cyclic populations of lemmings also fall into a predator-pit in the low phase remains to be determined. The low phase does not occur in every cycle and it is particularly difficult to explain. Progress in analyzing cyclic fluctuations has been made most rapidly when we define clear alternative hypotheses and carry out experimental manipulations on field populations. Much remains to be done on these small mammals.

Kr068 Krebs, C. and Boonstra, R. and Boutin, S. and Sinclair, A., 2001. What drives the 10-year cycle of snowshoe hares?. Bioscience, 51(1): 25-35.    Kr068.pdf      

Abstract: The ten-year cycle of snowshoe hares---one of the most striking features of the boreal forest--- is a product of the interaction between predation and food supplies, as large-scale experiments in the yukon have demonstrated.

Kr069 Krebs, C. J., 2011. Of lemmings and snowshoe hares: the ecology of Northern Canada. Proc. R. Soc. Lond. Ser. B Biol. Sci., 278(1705): 481-489.    Kr069.pdf      

Abstract: Two population oscillations dominate terrestrial community dynamics in northern Canada. In the boreal forest, the snowshoe hare (Lepus americanus) fluctuates in cycles with an 8-10 year periodicity and in tundra regions lemmings typically fluctuate in cycles with a 3-4 year periodicity. I review 60 years of research that has uncovered many of the causes of these population cycles, outpar areas of controversy that remain and suggest key questions to address. Lemmings are keystone herbivores in tundra ecosystems because they are a key food resource for many avian and mammalian predators and are a major consumer of plant production. There remains much controversy over the role of predation, food shortage and social interactions in causing lemming cycles. Predation is well documented as a significant mortality factor limiting numbers. Food shortage is less likely to be a major limiting factor on population growth in lemmings. Social interactions might play a critical role in reducing the rate of population growth as lemming density rises. Snowshoe hares across the boreal forest are a key food for many predators and their cycles have been the subject of large-scale field experiments that have pinpointed predation as the key limiting factor causing these fluctuations. Predators kill hares directly and indirectly stress them by unsuccessful pursuits. Stress reduces the reproductive rate of female hares and is transmitted to their offspring who also suffer reduced reproductive rates. The maternal effects produced by predation risk induce a time lag in the response of hare reproductive rate to density, aiding the cyclic dynamics.

Kr070 Kress, A. and Saurer, M. and Buentgen, U. and Treydte, K. S. and Bugmann, H. and Siegwolf, R. T. W., 2009. Summer temperature dependency of larch budmoth outbreaks revealed by alpine tree-ring isotope chronologies. Oecologia, 160(2): 353-365.    Kr070.pdf      

Abstract: Larch budmoth (LBM, Zeiraphera diniana Gn.) outbreaks cause discernable physical alteration of cell growth in tree rings of host subalpine larch (Larix decidua Mill.) in the European Alps. However, it is not clear if these outbreaks also impact isotopic signatures in tree-ring cellulose, thereby masking climatic signals. We compared LBM outbreak events in stable carbon and oxygen isotope chronologies of larch and their corresponding tree-ring widths from two high-elevation sites (1800-2200 m a.s.l.) in the Swiss Alps for the period AD 1900-2004 against isotope data obtained from non-host spruce (Picea abies). At each site, two age classes of tree individuals (150-250 and 450-550 years old) were sampled. Inclusion of the latter age class enabled one chronology to be extended back to AD 1650, and a comparison with long-term monthly resolved temperature data. Within the constraints of this local study, we found that: (1) isotopic ratios in tree rings of larch provide a strong and consistent climatic signal of temperature; (2) at all sites the isotope signatures were not disturbed by LBM outbreaks, as shown, for example, by exceptionally high significant correlations between non-host spruce and host larch chronologies; (3) below-average July to August temperatures and LBM defoliation events have been coupled for more than three centuries. Dampening of Alps-wide LBM cyclicity since the 1980s and the coincidence of recently absent cool summers in the European Alps reinforce the assumption of a strong coherence between summer temperatures and LBM defoliation events. Our results demonstrate that stable isotopes in tree-ring cellulose of larch are an excellent climate proxy enabling the analysis of climate-driven changes of LBM cycles in the long term.

Ku071 Kurz, W. A. and Stinson, G. and Rampley, G. J. and Dymond, C. C. and Neilson, E. T., 2008. Risk of natural disturbances makes future contribution of Canada's forests to the global carbon cycle highly uncertain. PNAS, 105(5): 1551-1555.    Ku071.pdf    Ku071_S.pdf      

Abstract: A large carbon sink in northern land surfaces inferred from global carbon cycle inversion models led to concerns during Kyoto Protocol negotiations that countries might be able to avoid efforts to reduce fossil fuel emissions by claiming large sinks in their managed forests. The greenhouse gas balance of Canada's managed forest is strongly affected by naturally occurring fire with high interannual variability in the area burned and by cyclical insect outbreaks. Taking these stochastic future disturbances into account, we used the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) to project that the managed forests of Canada could be a source of between 30 and 245 Mt CO2e yr1 during the first Kyoto Protocol commitment period (20082012). The recent transition from sink to source is the result of large insect outbreaks. The wide range in the predicted greenhouse gas balance (215 Mt CO2e yr1) is equivalent to nearly 30% of Canada's emissions in 2005. The increasing impact of natural disturbances, the two major insect outbreaks, and the Kyoto Protocol accounting rules all contributed to Canada's decision not to elect forest management. In Canada, future efforts to influence the carbon balance through forest management could be overwhelmed by natural disturbances. Similar circumstances may arise elsewhere if global change increases natural disturbance rates. Future climate mitigation agreements that do not account for and protect against the impacts of natural disturbances, for example, by accounting for forest management benefits relative to baselines, will fail to encourage changes in forest management aimed at mitigating climate change.

Ku075 Kurz, W., 2008. Making the paper: Werner Kurz. Nature, 452(7190): x-x.    Ku075.pdf   
Ku076 Kurz, W. A. and Dymond, C. C. and Stinson, G. and Rampley, G. J. and Neilson, E. T. and Carroll, A. L. and Ebata, T. and Safranyik, L., 2008. Mountain pine beetle and forest carbon feedback to climate change. Nature, 452(7190): 987-990.    Ku076.pdf    Ku076_S.pdf      

Abstract: The mountain pine beetle (Dendroctonus ponderosae Hopkins, Coleoptera: Curculionidae, Scolytinae) is a native insect of the pine forests of western North America, and its populations periodically erupt into large-scale outbreaks1, 2, 3. During outbreaks, the resulting widespread tree mortality reduces forest carbon uptake and increases future emissions from the decay of killed trees. The impacts of insects on forest carbon dynamics, however, are generally ignored in large-scale modelling analyses. The current outbreak in British Columbia, Canada, is an order of magnitude larger in area and severity than all previous recorded outbreaks4. Here we estimate that the cumulative impact of the beetle outbreak in the affected region during 2000--2020 will be 270 megatonnes (Mt) carbon (or 36 g carbon m-2 yr-1 on average over 374,000 km2 of forest). This impact converted the forest from a small net carbon sink to a large net carbon source both during and immediately after the outbreak. In the worst year, the impacts resulting from the beetle outbreak in British Columbia were equivalent to 75% of the average annual direct forest fire emissions from all of Canada during 1959--1999. The resulting reduction in net primary production was of similar magnitude to increases observed during the 1980s and 1990s as a result of global change5. Climate change has contributed to the unprecedented extent and severity of this outbreak6. Insect outbreaks such as this represent an important mechanism by which climate change may undermine the ability of northern forests to take up and store atmospheric carbon, and such impacts should be accounted for in large-scale modelling analyses.

Ku080 Kurz, W. A. and Stinson, G. and Rampley, G., 2008. Could increased boreal forest ecosystem productivity offset carbon losses from increased disturbances?. Phil. Trans. R. Soc. Lond. B, 363(1501): 2261-2269.    Ku080.pdf      

Abstract: To understand how boreal forest carbon (C) dynamics might respond to anticipated climatic changes, we must consider two important processes. First, projected climatic changes are expected to increase the frequency of fire and other natural disturbances that would change the forest age-class structure and reduce forest C stocks at the landscape level. Second, global change may result in increased net primary production (NPP). Could higher NPP offset anticipated C losses resulting from increased disturbances? We used the Carbon Budget Model of the Canadian Forest Sector to simulate rate changes in disturbance, growth and decomposition on a hypothetical boreal forest landscape and to explore the impacts of these changes on landscape-level forest C budgets. We found that significant increases in net ecosystem production (NEP) would be required to balance C losses from increased natural disturbance rates. Moreover, increases in NEP would have to be sustained over several decades and be widespread across the landscape. Increased NEP can only be realized when NPP is enhanced relative to heterotrophic respiration. This study indicates that boreal forest C stocks may decline as a result of climate change because it would be difficult for enhanced growth to offset C losses resulting from anticipated increases in disturbances.

La004iw Lassance, J.-M. and Groot, A. T. and Lienard, M. A. and Antony, B. and Borgwardt, C. and Andersson, F. and Hedenstrom, E. and Heckel, D. G. and Lofstedt, C., 2010. Allelic variation in a fatty-acyl reductase gene causes divergence in moth sex pheromones. Nature, 466(7305): 486.    La004iw.pdf      

Abstract: Pheromone-based behaviours are crucial in animals from insects to mammals(1,2), and reproductive isolation is often based on pheromone differences(1-4). However, the genetic mechanisms by which pheromone signals change during the evolution of new species are largely unknown(4). In the sexual communication system of moths (Insecta: Lepidoptera), females emit a species-specific pheromone blend that attracts males over long distances(1,2,4). The European corn borer, Ostrinia nubilalis, consists of two sex pheromone races, Z and E, that use different ratios of the cis and trans isomers of acetate pheromone components(5). This subtle difference leads to strong reproductive isolation in the field between the two races(6,7), which could represent a first step in speciation. Female sex pheromone production and male behavioural response are under the control of different major genes(8,9), but the identity of these genes is unknown. Here we show that allelic variation in a fatty-acyl reductase gene essential for pheromone biosynthesis accounts for the phenotypic variation in female pheromone production, leading to race-specific signals. Both the cis and trans isomers of the pheromone precursors are produced by both races, but the precursors are differentially reduced to yield opposite ratios in the final pheromone blend as a result of the substrate specificity of the enzymes encoded by the Z and E alleles. This is the first functional characterization of a gene contributing to intraspecific behavioural reproductive isolation in moths, highlighting the importance of evolutionary diversification in a lepidopteran-specific family of reductases. Accumulation of substitutions in the coding region of a single biosynthetic enzyme can produce pheromone differences resulting in reproductive isolation, with speciation as a potential end result.

La166 Lavorel, S. and Díaz, S. and Cornelissen, J. H. C. and Garnier, E. and Harrison, S. P. and McIntyre, S. and Pausas, J. G. and Pérez-Harguindeguy, N. and Roumet, C. and Urcelay, C., 2007. Plant functional types: Are we getting any closer to the Holy Grail?. In: Canadell, J. G. and Pataki, D. E. and Pitelka, L. F. (eds.), Terrestrial ecosystems in a changing world. Springer-Verlag, Berlin, 149-164pp.    La166.pdf      
Le146 Lenihan, J. M. and Daly, C. and Bachelet, D. and Neilson, R. P., 1998. Simulating broad-scale fire severity in a Dynamic Global Vegetation Model. Northwest Sci., 72(Spec. Iss.): 91-103.    Le146.pdf      

Abstract: Simulating the impact of fire in a broad-scale Dynamic Vegetation Model (DGVM) used for global change impact assessments requires components and concepts not part of existing fire modeling systems. The focus shifts from fire behavior and danger at the small scale to the system-specific impacts of fire at the broad scale (i.e., fire severity). MCFIRE, a broad-scale fire severity model we are currently developing as part of our MAPSS-CENTURY DGVM, simulates the occurrence and impacts (i.e., vegetation mortality and fuel consumption) of relatively infrequent and extreme events historically responsible for the majority of fire disturbance to ecosystems. The occurrence of severe fire is strongly related to synoptic-scale climatic conditions producing extended drought, which is indicated in MCFIRE by the low moisture content of large dead fuels. Due to constraints posed by currently available datasets, we have been developing our DGVM model on a relatively fine-scale data grid at a landscape-scale, but we will implement the model at regional to global scales on much coarser data grids. Constraints on the broad-scale impact of severe fire imposed by the fine-scale heterogeneity of fuel properties will be represented in our coarse-scale simulations by sub-grid parameterizations of the fire behavior and effects algorithms for distinct land surface types. Ecosystem structure and function are often constrained by disturbance, so it is critical to include disturbance processes in dynamic vegetation models used to assess the potential broad-scale impact of global change. The ability to simulate the impact of changes in fire severity on vegetation and the atmosphere has been a central focus in the development of the MAPSS-Century Dynamic Global Vegetation Model.

Le232 Le Quere, C. and Takahashi, T. and Buitenhuis, E. T. and Roedenbeck, C. and Sutherland, S. C., 2010. Impact of climate change and variability on the global oceanic sink of CO2. Glob. Biogeochem. Cycles, 24: GB4007.    Le232.pdf      

Abstract: About one quarter of the CO2 emitted to the atmosphere by human activities is absorbed annually by the ocean. All the processes that influence the oceanic uptake of CO2 are controlled by climate. Hence changes in climate (both natural and human-induced) are expected to alter the uptake of CO2 by the ocean. However, available information that constrains the direction, magnitude, or rapidity of the response of ocean CO2 to changes in climate is limited. We present an analysis of oceanic CO2 trends for 1981 to 2007 from data and a model. Our analysis suggests that the global ocean responded to recent changes in climate by outgassing some preindustrial carbon, in part compensating the oceanic uptake of anthropogenic CO2. Using a model, we estimate that climate change and variability reduced the CO2 uptake by 12\% compared to a simulation where constant climate is imposed, and offset 63\% of the trend in response to increasing atmospheric CO2 alone. The response is caused by changes in wind patterns and ocean warming, with important nonparar effects that amplify the response of oceanic CO2 to changes in climate by > 30\%.

Le233 Le Quere, C., 2010. Trends in the land and ocean carbon uptake. Curr. Opinion in Environ. Sustainability, 2(4): 219-224.    Le233.pdf      

Abstract: Only about 45\% of the total CO2 emitted from fossil fuel burning and land use change stayed in the atmosphere on average during the past few decades. The remaining CO2 was taken up by the carbon reservoirs (the 'CO2 sinks') in the ocean and on land. The sinks are sensitive to climate and elevated CO2 levels. Their efficiency in removing CO2 emissions from the atmosphere is expected to decrease in the future under increasing atmospheric CO2 because of their response to elevated CO2 levels, warming and other climate changes. Recent evidence from observations and models suggests that the efficiency of the sinks could have already decreased in the past few decades, but the uncertainties are very large. There is an urgent need for reducing these uncertainties by better monitoring the CO2 emissions and sinks, and by improving our understanding of the sinks dynamics.

Le235 Levis, S. and Bonan, G. B. and Vertenstein, M. and Oleson, K. W., 2004. The Community Land Model's Dynamic Global Vegetation Model (CLM-DGVM): technical description and user's guide. Technical Note, National Center for Atmospheric Research (NCAR), Climate and Global Dynamics Division, Boulder, Col., USA, 50pp.    Le235.pdf      
Li039 Lischke, H. and Guisan, A. and Fischlin, A. and Williams, J. and Bugmann, H., 1998. Vegetation responses to climate change in the Alps: modeling studies. In: Cebon, P. and Dahinden, U. and Davies, H. C. and Imboden, D. M. and Jager, C. C. (eds.), Views from the Alps: regional perspectives on climate change. MIT Press, Results from the Coordinated Project CLEAR (Climate and Environment in Alpine Regions), Module 1 of the Swiss Priority Programme Environment, Boston, Massachusetts a.o., 309-350pp.    Li039.pdf      
Li042 Lischke, H. and Löffler, T. J. and Fischlin, A., 1998. Aggregation of individual trees and patches in forest succession models: Capturing variability with height structured , random, spatial distributions. Theor. Popul. Biol., 54(3): 213-226.    Li042.pdf      

Abstract: Individual based, stochastic forest patch models have the potential to realistically describe forest dynamics. However, they are mathematically intransparent and need long computing times. We simplified such a forest patch model by aggregating the individual trees on many patches to height-structured tree populations with theoretical random dispersions over the whole simulated forest area. The resulting distribution-based model produced results similar to those of the patch model under a wide range of conditions. We concluded that the height- structured tree dispersion is an adequate population descriptor to capture the stochastic variability in a forest and that the new approach is generally applicable to any patch model. The simplified model required only 4.1% of the computing time needed by the patch model. Hence, this new model type is well-suited for applications where a large number of dynamic forest simulations is required.

Li043 Lischke, H. and Lotter, A. F. and Fischlin, A., 2002. Untangling a Holocene pollen record with forest model simulations and independent climate data. Ecol. Modelling, 150(1-2): 1-21.    Li043.pdf      

Abstract: Adaptation potential of forests to rapid climatic changes can be assessed from vegetation dynamics during past climatic changes as preserved in fossil pollen data. However, pollen data reflect the integrated effects of climate and biotic processes, such as establishment, survival, competition, and migration. To disentangle these processes, we compared an annually laminated late Würm and Holocene pollen record from the Central Swiss Plateau with simulations of a dynamic forest patch model. All input data used in the simulations were largely independent from pollen data; i.e. the presented analysis is non-circular. Temperature and precipitation scenarios were based on reconstructions from pollen-independent sources. The earliest arrival times of the species at the study site after the last glacial were inferred from pollen maps. We ran a series of simulations under different combinations of climate and immigration scenarios. In addition, the sensitivity of the simulated presence/absence of four major species to changes in the climate scenario was examined. The pattern of the pollen record could partly be explained by the used climate scenario, mostly by temperature. However, some features, in particular the absence of most species during the late Würm could only be simulated if the winter temperature anomalies of the used scenario were decreased considerably. Consequently, we had to assume in the simulations, that most species immigrated during or after the Younger Dryas (12 000 years BP), Abies and Fagus even later. Given the timing of tree species immigration, the vegetation was in equilibrium with climate during long periods, but responded with lags at the time-scale of centuries to millennia caused by a secondary succession after rapid climatic changes such as at the end of Younger Dryas, or immigration of dominant taxa. Climate influenced the tree taxa both directly and indirectly by changing inter-specific competition. We concluded, that also during the present fast climatic change, species migration might be an important process, particularly if geographic barriers, such as the Alps are in the migrational path.

Li138 Lindgren, A. and Klint, J. and Moen, J., 2007. Defense mechanisms against grazing: a study of trypsin inhibitor responses to simulated grazing in the sedge carex bigelowii. OIKOS, 116(9): 1540-1546.    Li138.pdf      

Abstract: Trypsin inhibitors have been suggested to constitute an inducible defense in the sedge Carex bigelowii, and some former studies suggest that this might be a cause for the cyclic population dynamics in many alpine and arctic small mammals, for example lemmings (Lemmus lemmus). We investigated this further by using a method of simulated grazing (clipping) at different intensities, in three different habitats with varying resource availability, with different harvest times (hours after clipping), and two different stages of ramets (reproductive/vegetative) in a study from the Swedish mountain range. Our results do not indicate that C. bigelowii has an inducible defense constituted by an increase in trypsin inhibitor activity (TIA), but rather that the amount of soluble plant proteins (SPP) is lowered in wounded plants. The responses were somewhat different in the three habitats, with ramets growing in the marsh showing the highest ratio of TIA to SPP, due to low amounts of SPP. We did not find any significant effects of harvest time, or of the stage of the ramet that could support the hypothesis of an inducible defense. To conclude, we could not find any evidence for an inducible defense consisting of trypsin inhibitors in Carex bigelowii ramets, but we did find variations in the amount of SPP that may have nutritional consequences for herbivores.

Li139 Liebhold, A. and Elkinton, J. and Williams, D. and Muzika, R., 2000. What causes outbreaks of the gypsy moth in North America?. Popul. Ecol., 42(3): 257-266.    Li139.pdf      

Abstract: The gypsy moth has been present in North America for more than 100 years, and in many of the areas where it has become established outbreaks occur with varying degrees of periodicity. There also exists extensive spatial synchrony in the onset of outbreaks over large geographic regions. Density-dependent mortality clearly limits high-density populations, but there is little evidence for strong regulation of low-density populations. Predation by small mammals appears to be the major source of mortality affecting low-density populations. but because these are generalist predators and gypsy moths are a less preferred food item, mammals do not appear to regulate populations in a density-dependent fashion. Instead, predation levels appear to be primarily determined by small mammal abundance, which is in turn closely linked to the production of acorns that are a major source of food for overwintering predator populations. Mast production by host oak trees is typically variable among years, but considerable spatial synchrony in masting exists over large geographic areas. Thus, it appears that the temporal and spatial patterns of mast production may be responsible for the episodic and spatially synchronous behavior of gypsy moth outbreaks in North America. This multitrophic relationship among mast, predators, and gypsy moths represents a very different explanation of forest insect outbreak dynamics than the more widely applied theories based upon predator-prey cycles or feedbacks with host foliage quality.

Li140 Li, Y. and Feng, Z. and Swihart, R. and Bryant, J. and Huntly, N., 2006. Modeling the impact of plant toxicity on plant-herbivore dynamics. J. Dyn. Diff. Equ., 18(4): 1021-1042.    Li140.pdf      

Abstract: Numerous empirical studies over the past two decades have documented substantial effects of plant toxins on diet choice and feeding behavior of herbivores, but analytical models have failed thus far to incorporate toxin-mediated effects of browsing on plant population dynamics. We study a mathematical model that incorporates plant toxicity in the functional response of plant-herbivore interactions. The model also includes a Lotka-Volterra type competition between plants. The model exhibits a rich variety of complex dynamics including Hopf bifurcation and period-doubling bifurcations. Differences in dynamical behavior stem from interspecific differences in plant biology and strategies for growth and defense as well as variation in responses of herbivores to toxins. Analyses suggest that for realistic parameter values, herbivores are capable of promoting coexistence of plant species by ameliorating competitive effects and hence enhancing biodiversity.

Ll004 Lloyd, A. L. and May, R. M., 1999. Synchronicity, chaos and population cycles: spatial coherence in an uncertain world. Tree, 14(11.Nov.): 417-418.    Ll004.pdf   

Lo131 Logan, J. A. and Powell, J. A., 2001. Ghost forests, global warming, and the mountain pine beetle (Coleoptera: Scolytidae). Am. Entomol., 47: 160-172.    Lo131.pdf

Abstract: Outbreaks of the mountain pine beetle are an important part of ecological cycles in western pine forests and have provided researchers with insights into both the beetle's and the forest's evolutionary adaptability

Lo155 Lopatin, V. and Abaturov, B., 1994. Comparison of populations of herbivorous mammals with density, trophic, and density-trophic dependent types of regulation. Zhurnal Obshchei Biologii, 55(4-5): 573-582.   

Abstract: Mathematical models of population dynamics of herbivorous mammals with three types of regulations are formalized and generalized. Variation of some population characteristics under influence of fodder vegetation productivity and population parameters are considered. Regulatory mechanisms and productivity characteristics of populations (biomass, productivity, production formation efficiency) are analyzed for different types of regulation. Populations with mixed density and trophic dependent regulation are shown to take intermediate position between those with density dependent and with trophic dependent regulations. The first type of regulation thus may be considered as more general one, while the two others are its extreme cases. Mechanisms of realization of these regulation types and their examples are considered.

Lu063 Lucarotti, C. J. and Eveleigh, E. S. and Royama, T. and Morin, B. and McCarthy, P. and Ebling, P. M. and Kaupp, W. J. and Guertin, C. and Arella, M., 2004. Prevalence of baculoviruses in spruce budworm (Lepidoptera : Tortricidae) populations in New Brunswick. Can. Entomol., 136(2): 255-264.    Lu063.pdf      

Abstract: Outbreak and declining populations of spruce budworm (Choristoneura fumiferana (Clem.)) were sampled extensively at three locations in New Brunswick, Canada, between 1982 and 1992 and were examined for the prevalence of granulosis and nuclear polyhedrosis viruses (Baculoviridae). Larvae, pupae, and adults were collected using a variety of methods. Spruce budworm nuclear polyhedrosis virus (CfMNPV) genomic DNA probes and wet-mount light microscopy were used to determine CfMNPV prevalence in 50 274 juvenile spruce budworms. Spruce budworm granulosis virus (ChfuGV) genomic DNA probes were used to determine the prevalence of ChfuGV in 25 703 of these same samples. The prevalence of both viruses was low, with ChfuGV and CfMNPV not found in more than 15% and 2%, respectively, of samples in any collection in a given year. Prevalence of ChfuGV was greatest in mid- to late June in sixth-instar larvae. Each virus was detected in only two of 2177 female moths and in none of the 420 male moths examined. In the entire collection, cytoplasmic polyhedrosis virus (Reoviridae) was detected in only two budworm larvae and entomopoxvirus (Poxviridae) was not detected in any.

Lu077 Lucht, W. and Schaphoff, S. and Erbrecht, T. and Heyder, U. and Cramer, W., 2006. Terrestrial vegetation redistribution and carbon balance under climate change. Carbon Balance Manage., 1(6): 1-7.    Lu077.pdf      

Abstract: Background Dynamic Global Vegetation Models (DGVMs) compute the terrestrial carbon balance as well as the transient spatial distribution of vegetation. We study two scenarios of moderate and strong climate change (2.9K and 5.9K terrestrial temperature increase over present) to investigate the spatial redistribution of major vegetation types and their carbon balance in the year 2100. Results The world's land vegetation will be more deciduous than at present, and contain about 125 billion tons of additional carbon. While a recession of the boreal forest is simulated in some areas, along with a general expansion to the north, we do not observe a reported collapse of the central Amazonian rain forest. Rather, a decrease of biomass and a change of vegetation type occurs in its northeastern part. The ability of the terrestrial biosphere to sequester carbon from the atmosphere declines strongly in the second half of the 21st century. Conclusions Climate change will cause widespread shifts in the distribution of major vegetation functional types on all continents by the year 2100.

Lu099 Luo, Y., 2007. Terrestrial carbon-cycle feedback to climate warming. Annu. Rev. Ecol. Evol. Syst., 38: 683-712.    Lu099.pdf      

Abstract: The coupled carbon-climate models reported in the literature all demonstrate a positive feedback between terrestrial carbon cycles and climate warming. A primary mechanism underlying the modeled positive feedback is the kinetic sensitivity of photosynthesis and respiration to temperature. Field experiments, however, suggest much richer mechanisms driving ecosystem responses to climate warming, including extended growing seasons, enhanced nutrient availability, shifted species composition, and altered ecosystem-water dynamics. The diverse mechanisms likely define more possibilities of carbon-climate feedbacks than projected by the kinetics-based models. Nonetheless, experimental results are so variable that we have not generated the necessary insights on ecosystem responses to effectively improve global models. To constrain model projections of carbon-climate feedbacks, we need more empirical data from whole-ecosystem warming experiments across a wide range of biomes, particularly in tropic regions, and closer interactions between models and experiments.

Ma343 Malausa, T. and Bethenod, M. T. and Bontemps, A. and Bourguet, D. and Cornuet, J. M. and Ponsard, S., 2005. Assortative mating in sympatric host races of the European corn borer. Science, 308(5719): 258-260.    Ma343.pdf      

Abstract: Although a growing body of work supports the plausibility of sympatric speciation in animals, the practical difficulties of directly quantifying reproductive isolation between diverging taxa remain an obstacle to analyzing this process. We used a combination of genetic and biogeochemical markers to produce a direct field estimate of assortative mating in phytophagous insect populations. We show that individuals of the same insect species, the European corn borer Ostrinia nubilalis, that develop on different host plants can display almost absolute reproductive isolation-the proportion of assortative mating was >95%-even in the absence of temporal or spatial isolation.

Ma472 Maraseni, T. N. and Cockfield, G., 2011. Crops, cows or timber? Including carbon values in land use choices. Agric. Ecosyst. & Environ., 140(1-2): 280-288.    Ma472.pdf      

Abstract: Farm forestry is a very minor land use in the inland agricultural landscapes of Australia. The Australian Government intends to introduce a program to encourage landholders to trade the carbon sequestration value of plantations and this may change the relative profitability of plantations against other agricultural land uses. This research compares the returns from a timber and 'carbon' plantation, with those from grazing and a common crop rotation in the Kingaroy area of Queensland. Typical production patterns for all systems were developed from producer and expert knowledge and soil and vegetation sampling were used to estimate sequestration rates. The costs and benefits of all land use systems were converted into monetary terms and discounted to produce net present values. With a standard discount rate and average commodity prices based on recent history, cultivation is the most profitable option, followed by pasture and plantations. After the inclusion of carbon, plantations are the most profitable option, followed by pasture and cultivation. A number of qualifications of these findings are also discussed. (C) 2010 Elsevier B.V. All rights reserved.

Me283 Metsaranta, J. M. and Kurz, W. A. and Neilson, E. T. and Stinson, G., 2010. Implications of future disturbance regimes on the carbon balance of Canada's managed forest (2010-2100). Tellus (Ser. B: Chem. Phys. Meteorol.), 62(5): 719-728.    Me283.pdf      

Abstract: Recent increases in fire and insect disturbances have contributed to a transition of Canada's managed forest carbon balance from sink to source. Further increases in area burned could contribute positive feedback to climate change. We made probabilistic forecasts of the recovery of C sinks in Canada's managed forest between 2010 and 2100 under two assumptions about future area burned by wildfire: (1) no increase relative to levels observed in the last half of the 20th century and (2) parar increases by a factor of two or four (depending on region) from 2010 to 2100. Recovery of strong C sinks in Canada's managed forest will be delayed until at least the 2030s because of insect outbreaks, even if predicted increases in area annually burned do not occur. After 2050, our simulations project an annual probability of a sink near 70\% with no increase in area burned and 35\% with increasing area burned. All simulations project a cumulative C source from 2010-2100, even if annual area burned does not increase. If the sink strength of terrestrial ecosystems is reduced because of increasing natural disturbances, then it will become more difficult to achieve global atmospheric CO2 stabilization targets.

Mo004 Morris, R. F. (eds.), 1963. The dynamics of epidemic spruce budworm populations. Mem. Ent. Soc. Can., 95(31): 1-332.    Mo004.pdf    Mo004_S.pdf   
Mo161 Morin, H. and Jardon, Y. and Gagnon, R., 2007. Relationship between spruce budworm outbreaks and forest dynamics in eastern North America. In: Johnson, E. A. and Miyanishi, K. (eds.), Plant Disturbance Ecology. Academic Press, Burlington, 555-577pp.    Mo161.pdf      

Abstract: In Chapter 15, Cooke et al. explain the periodic disturbances by native for- est-defoliating insects by examining the population dynamics of the insects. They argue that the population density of forest insects is determined by the ecological relationships among host plants, the herbivorous insects, and their natural enemies in a so-called tritrophic interaction. The objective of this chapter is to discuss the effects of these disturbances by native forest-defoliators on the forest dynamics. However, we cannot understand the effects of forest-defoliating insects without understanding the reciprocal effect of forest dynamics on the population dynamics of the insects. Because both are so closely related and difficult to separate, this chapter focuses on the relationship between disturbances caused by native forest-defoliating insects and forest dynamics, which is recognized as an important part of the tritrophic interactions described in Chapter 15, especially for the spruce budworm system.

Mo162 Molinar, F. and Navarro, J. and Holechek, J. and Galt, D. and Thomass, M., 2011. Long-term vegetation trends on grazed and ungrazed Chihuahuan desert rangelands. Rangeland Ecol. & Manage., 64(1): 104-108.    Mo162.pdf      

Abstract: Long-term information on the effects of managed grazing versus excluded grazing effects on vegetation composition of desert rangelands is limited. Our study objectives were to evaluate changes in frequency of vegetation components and ecological condition scores under managed livestock grazing and excluded livestock grazing over a 38-yr period at various locations in the Chihuahuan Desert of southwestern New Mexico. Sampling occurred in 1962, 1981, 1992, 1998, 1999, and 2000. Range sites of loamy (1), gravelly (2), sandy (2), and shallow sandy (2) soils were used as replications. Black grama (Bouteloua eriopoda Tort.) was the primary vegetation component at the seven locations. Dyksterhuis quantitative climax procedures were used to determine trends in plant frequency based on a 1.91-cm loop and rangeland ecological condition scores. Frequency measures of total perennial grass, black grama, tobosa (Hilaria mutica Buckley), total shrubs, honey mesquite (Prosopis glandulosa Torr.), and other vegetation components were similar on both grazed and ungrazed treatments (P > 0.1) at the beginning and end of the study. The amount of change in rangeland ecological condition scores was the same positive increase (14\%) for both grazed and ungrazed treatments. Major changes (P < 0.1) occurred within this 38-yr study period in ecological condition scores and frequency of total perennial grasses and black grama in response to annual fluctuations in precipitation. Based on this research, managed livestock grazing and excluded livestock grazing had the same long-term effects on change in plant frequency and rangeland ecological condition; thus, it appears that managed livestock grazing is sustainable on Chihuahuan desert rangelands receiving over 25 cm annual precipitation.

Mo163 Moen, J. and Oksanen, L., 1998. Long-term exclusion of folivorous mammals in two arctic-alpine plant communities: a test of the hypothesis of exploitation ecosystems. OIKOS, 82(2): 333-346.      

Abstract: During 1987-1994 we monitored changes in vegetation in exclosures and permanent open plots established in two contrasting habitats: a productive hemiarctic tall herb meadow and a less productive alpine snow-bed. In addition, we studied the survival and growth of transplanted tall herbs, woody plants and arctic-alpine plants together with their seed germination and seedling survival in the same habitats. The primary objective of the study was to test the following prediction of the hypothesis of exploitation ecosystems: exclusion of herbivorous vertebrates from the snow-bed initiates radical changes in the vegetation of the snow-bed, whereas in the tall herb meadow, the impact of grazer exclusion on the vegetation is modest. The vegetation within the snow-bed exclosures changed from a grassland to a herbfield during the experimental period. Transplanted tall herbs and seedlings of erect woody plants had high rates of survival and growth in snow-bed exclosures. No such changes were seen in the open snow-bed plots. Survival rates of transplanted woody plants and tall herbs in open snow-bed plots were low and the net growth rates of the survivors were close to zero. In the productive tall herb meadow, vegetational changes were modest on open plots and within exclosures. No clear treatment effects on survival or growth of transplanted woody plants and tall herbs were observed. The results of the experiment thus conformed to the predictions of the hypothesis of exploitation ecosystems.

Mu087 Münster-Swendsen, M. and Berryman, A., 2005. Detecting the causes of population cycles by analysis of R-functions: the spruce needle-miner, Epinotia tedella, and its parasitoids in danish spruce plantations. OIKOS, 108(3): 495-502.    Mu087.pdf      

Abstract: Explaining the causes of regular multi annual oscillations (cycles) in animal populations has been a major problem for ecology, partly due to a lack of methodological rigor. In this paper we show how the analysis of R-functions, the functional relationship between the per capita rate of change of a species and components of its environment, can be used to detect the causes of population cycles. Analysis of the R-functions enables one to separate cycles due to negative feedback between species (endogenous causes) from those forced by one-way effects (exogenous causes). We illustrate the approach by reference to the spruce needle-miner inhabiting Danish spruce plantations, and conclude that population cycles in this insect are probably caused by interactions with two species of parasitic hymenoptera.

Mu088 Murdoch, W. and Briggs, C. and Nisbet, R. and Kendall, B. and McCauley, E., 2003. Natural enemy specialization and the period of population cycles - reply. Ecol. Lett., 6(5): 384-387.    Mu088.pdf      

Abstract: The dynamical consequences of multiple-species interactions remain an elusive and fiercely debated topic. Recently, Murdoch and colleagues proposed a general rule for the dynamics of generalist natural enemies: when periodic, they exhibit single generation cycles (SGCs), similar to single species systems. This contrasts markedly with specialists, which tend to show classic (longer period) consumer--resource cycles. Using a wellstudied laboratory system, we show that this general rule is contradicted when we consider resource age-structure.

My013 Myers, J. H., 1988. Can a general hypothesis explain population cycles of forest Lepidoptera?. Adv. Ecol. Res., 18: 179-242.    My013.pdf   
My024 Myers, J. H., 1998. Synchrony in outbreaks of forest Lepidoptera: a possible example of the Moran effect. Ecology, 79(3): 1111-1117.    My024.pdf   

Abstract: I compiled information from the literature on 140 population outbreaks of 26 species of forest Lepidoptera that occurred between the years 1932 and 1992 in the Northern Hemisphere, including Asia, North America, and Europe. Considerable variation in the number of outbreaks occurred among years, with a tendency for outbreaks to be synchronous. Years of numerous outbreaks include 1948, 1956, 1964, the mid-1970s, and the mid-1980s. Published summaries of weather in the Northern Hemisphere indicate the occurrence of above-normal precipitation and cool temperatures between 1954 and 1957, and a high proportion of populations were at peak density in 1954 and 1956. Cool springs in 1964, 1965, and 1976 were also associated with outbreaks in a number of species of forest Lepidoptera. Periods of synchrony of population outbreaks and cool temperatures appear to be associated with troughs in the sunspot cycle. While the details of population dynamics of caterpillars are determined through endogenous processes that influence fecundity and mortality, exogenous forces, such as cool springs, may occasionally play a role in synchronizing populations in the Northern Hemisphere. Thus weather conditions may act as a Moran effect and synchronize fluctuating populations of forest caterpillars over large geographic areas. Read More: http://www.esajournals.org/doi/abs/10.1890/0012-9658(1998)079[1111:SIOOFL]2.0.CO;2

My048 Myers, J. and Kuken, B., 1995. Changes in the fecundity of tent caterpillars - a correlated character of disease resistance or sublethal effect of disease. Oecologia, 103(4): 475-480.    My048.pdf      

Abstract: Over the fluctuation in population density of tent caterpillars, Malacosoma californicum pluviale and M. disstria, fecundity changes from being high at peak density to low for several years during the decpar. During the increase phase, fecundity rapidly returns to moderately high levels with a further increase occurring toward the end of the increase phase. Two hypotheses which might explain these shifts are that (1) mortality from Viral disease which is common during population decpars selects for resistant individuals with low fecundity as an associated characteristic, and (2) sublethal viral disease reduces fecundity of moths during population decpar. In this study we observed rapid shifts in the frequencies of large and small egg masses and in the mean fecundity between different phases of the population fluctuation. Viral disease was more common in caterpillars from small egg masses of the forest tent caterpillar. These observations are consistent with the hypothesis that sublethal effects of virus reduce the fecundity of moths during the population decpar, but high fecundity is quickly restored when disease is rare during the population increase.

Na046 Nabuurs, G. J. and Masera, O. and Andrasko, K. and P. Benitez-Ponce, Boer, R. and Dutschke, M. and Elsiddig, E. and J. Ford-Robertson, Frumhoff, P. and Karjalainen, T. and Krankina, O. and Kurz, W. and Matsumoto, M. and Oyhantcabal, W. and Ravindranath, N. H. and Sanz Sanchez, M. J. and Zhang, X., 2007. Forestry. In: Metz, B. and Davidson, O. R. and Bosch, P. R. and Dave, R. and Meyer, L. A. (eds.), Climate change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge, UK, 541-584pp.    Na046.pdf   
No082 Nobre, C. and Brasseur, G. P. and Shapiro, M. A. and Lahsen, M. and Brunet, G. and Busalacchi, A. J. and Hibbard, K. and Seitzinger, S. and Noone, K. and Ometto, J. P., 2010. Addressing the complexity of the earth system. Bull. Am. Meteorol. Soc., 91(10): 1389-1396.    No082.pdf      

Abstract: This paper discusses the development of a prediction system that integrates physical, biogeochemical, and societal processes in a unified Earth system framework. Such development requires collaborations among physical and social scientists, and should include i) the development of global Earth system analysis and prediction models that account for physical, chemical, and biological processes in a coupled atmosphere--ocean--land--ice system; ii) the development of a systematic framework that links the global climate and regionally constrained weather systems and the interactions and associated feedbacks with bio-geochemistry, biology, and socioeconomic drivers (e.g., demography, global policy constraints, technological innovations) across scales and discippars; and iii) the exploration and development of methodologies and models that account for societal drivers (e.g., governance, institutional dynamics) and their impacts and feedbacks on environmental and climate systems.

Nu010 Nussbaumer, S. U. and Steinhilber, F. and Trachsel, M. and Breitenmoser, P. and Beer, J. and Blass, A. and Grosjean, M. and Hafner, A. and Holzhauser, H. and Wanner, H. and Zumbuehl, H. J., 2011. Alpine climate during the Holocene: a comparison between records of glaciers, lake sediments and solar activity. J. Quaternary Sci., 26(7): 703-713.    Nu010.pdf      

Abstract: The European Alps are very sensitive and vulnerable to climate change. Recent improvements in Alpine glacier length records and climate reconstructions from annually laminated sediments of Alpine Lake Silvaplana give the opportunity to investigate the relationship between these two data sets of Alpine climate. Two different time frames are considered: the last 500-1000 years as well as the last 7400 years. First, we found good agreement between the two different climate archives during the past millennium: mass accumulation rates and biogenic silica concentration are largely in phase with the glacier length changes of Mer de Glace and Unterer Grindelwaldgletscher, and with the records of glacier length of Grosser Aletschgletscher and Gornergletscher. Secondly, the records are compared with temporally highly resolved data of solar activity. The Sun has had a major impact on the Alpine climate variations in the long term, i.e. several centuries to millennia. Solar activity varies with the Hallstatt periodicity of about 2000 years. Hallstatt minima are identified around 500, 2500 and 5000 a. Around these times grand solar minima (such as the Maunder Minimum) occurred in clusters coinciding with colder Alpine climate expressed by glacier advances. During the Hallstatt maxima around 0, 2000 and 4500 a, the Alpine glaciers generally retreated, indicating a warmer climate. This is supported by archaeological findings at Schnidejoch, a transalpine pass in Switzerland that was only accessible when glaciers had retreated. On shorter timescales, however, the influence of the Sun cannot be as easily detected in Alpine climate change, indicating that in addition to solar forcing, volcanic influence and internal climate variations have played an important role. Copyright (C) 2011 John Wiley \& Sons, Ltd.

Ok007 Oksanen, T. and Oksanen, L. and Dahlgren, J. and Olofsson, J., 2008. Arctic lemmings, Lemmus spp. and Dicrostonyx spp.: integrating ecological and evolutionary perspectives. Evol. Ecol. Res., 10(3): 415-434.    Ok007.pdf      

Abstract: Question: What do the evolution and the fluctuation patterns of arctic lemmings - Lemmus spp. and Dicrostonyx spp. - tell us about their population dynamics and the influence of lemmings on the ecology and evolution of arctic plants? Methods: We reviewed the literature concerning the evolution of arctic lemmings and analysed their current fluctuation patterns with a focus on the following aspects: (1) changes in morphology related to feeding ecology; (2) per capita rate of population growth during the year preceding the peak (r(p)), predicted to be high for arvicopar rodents interacting with the winter forage plants and low for arvicopar rodents interacting with specialized predators; (3) the skew of logarithmically transformed density data (sk(d)), predicted to be zero for arvicopars interacting with their winter forage plants, negative for arvicopars interacting with specialized predators, and positive for arvicopars interacting with both seasonally renewed and depletable winter forage plants (the 'Barrow model' of Turchin and Batzli, 200 1). Moreover, we conducted spectral analysis of those density records, which were at least 15 years long. Here predator-arvicopar models predict that similar spectral density profiles, with statistically significant peaks, are obtained with untransformed and logarithmically transformed data, whereas arvicopar-plant models predict that such profiles are only obtained using logarithmically transformed data. Key insights: Arctic lemmings differ from other microtine rodents by having several features which increase their foraging efficiency under harsh conditions at the cost of reduced agility. These features were acquired rapidly at the dawn of the Pleistocene. Density fluctuations of all arctic lemming populations, for which sufficient data are available, correspond to the predictions of the 'Barrow model' and differ from the predictions of predator-arvicopar models. Our interpretation is as follows. When the Polar Sea froze, the primary productivity of northernmost Eurasia and North America was reduced, causing a shift from predation-controlled to food-limited dynamics in microtine rodents. This change in population dynamics triggered an extraordinarily rapid change in the characteristics of lemmings and precipitated an intense, sustained lemming-vegetation interaction, as old as the tundra itself, which has probably played a major role in the evolution of arctic plants. Predictions: Increasing primary productivity along the southern (lower) boundary of the ranges of arctic lemmings should lead to their elimination by voles via apparent competition. Exclusion of lemmings should initiate dramatic changes in the vegetation of those tundra habitats, which have at least moderate snow cover and do not freeze in solid ice in winter. Exclusion of predators should have no impact on dynamics of inland populations of arctic lemmings.

Ok008 Oksanen, T. and Oksanen, L. and Schneider, M. and Aunapuu, M., 2001. Regulation, cycles and stability in northern carnivore-herbivore systems: back to first principles. OIKOS, 94(1): 101-117.    Ok008.pdf      

Abstract: In studies on dynamics of northern predator-prey systems. two assumptions are often made. First. the bifurcation from stable to cyclic dynamics is seen as a consequence of changing generalist-specialist ratio. ultimately due to reduced prey diversity at high latitudes and the negative impact of snow on the efficiency of generalists as predators of small, folivorous mammals. Supposedly, the primary mechanism is the qualitative difference between the functional response of specialist and generalist predators. Second, the interaction between large predators and ungulates is supposed to be prone to lead to two alternative equilibria, one where predation regulates ungulates at a relatively low equilibrium and another. where ungulate densities are close to carrying capacity, In the first-mentioned issue, our analysis corroborates the general idea of snow favoring specialists and leading to cycles. However, differences in functional response appear to be of secondary importance only, and rather special conditions are required for generalists to have a stabilizing type III functional response. A destabilizing type If functional response or a slight modification of it should be common in generalists, too, as also indicated by the classical experiments. Stability of generalist dominated systems seems primarily to derive from their relative inefficiency, allowing prey's density-dependent mechanisms to play a bigger role in the neighborhood of the equilibrium, Moreover. the main destabilizing impact of deep, long-lasting snow cover appears to lie in the protection it offers to the efficient but vulnerable specialists, which are eliminated or marginalized by intraguild predation in areas with snow-free winters, unless the habitat offers some other form of efficient protection. As for the conjecture of multiple equilibria in northern wolf-ungulate systems. it seems to be derived from an erroneous operational definition of numerical response and has little if any empirical support. Available data suggest that predation limitation of folivorous mammals prevails along the entire gradient from relatively productive low arctic habitats to the humid parts of the temperate zone. provided that the numbers of predators are not controlled by man.

Ok009 Oksanen, L. and Oksanen, T., 2000. The logic and realism of the hypothesis of exploitation ecosystems. Am. Nat., 155(6): 703-723.    Ok009.pdf      

Abstract: Hypotheses on trophic dynamics in terrestrial ecosystems fall into two major categories: those in which plants are assumed to be invulnerable to their consumers and those in which the build-up of plant biomass is assumed to require top-down control of folivores. The hypothesis of exploitation ecosystems (EEH) belongs to the latter category and focuses particularly on the consequences of the high energetic costs of maintenance of endotherms. Carnivorous endotherms require relatively high prey densities in order to break even. Moreover, they are dependent on folivorous prey during the limiting season, at least at high latitudes. The endotherm branch of the grazing web is thus predicted to collapse From three-link trophic dynamics (carnivores --> folivores --> plants --> inorganic resources) to two-link dynamics (folivores --> plants --> inorganic resources) along gradients of decreasing primary productivity. Consequently, the vegetation of cold and unproductive areas is predicted to be under intense winter grazing pressure, which prevents the accumulation of aboveground plant biomass and excludes erect woody plants. In the most extreme habitats (e.g., polar deserts and their high alpine counterparts), even folivorous endotherms are predicted to be absent, and the scanty vegetation is predicted to be structured by preemptive competition. Within temperature-determined productivity gradients, EEH is corroborated by biomass patterns, by patterns in the structure and dynamics of carnivore, folivore, and plant communities, and by experimental results. The general idea of top-down trophic dynamics is supported for other autotroph-based systems, too, but the relevance and sufficiency of the energy constraint in explaining patterns in trophic dynamics appears to be variable. Moreover, critical empirical evidence for or against the capacity of folivorous insects to regulate plant biomass has not yet been obtained. Another open question is the ability of boreal and temperate browsers, evolved in productive environments with intense predation pressure and abundance of forage, to prevent the regeneration of the least palatable tree species. There are, thus, many open questions waiting to be answered and many exciting experiments waiting to be conducted.

Ol032 Oli, M., 2003. Population cycles of small rodents are caused by specialist predators: or are they?. Tree, 18(3): 105-107.    Ol032.pdf    Ol032_S.pdf      

Abstract: Predation by specialist mammalian predators has been hypothesized to be the primary cause of multi-annual density fluctuations ('population cycles') in voles. Using a series of replicated field experiments, Isla Graham and Xavier Lambin have now shown that specialist mammalian predators are neither necessary nor sufficient to drive field vole Microtus agrestis population cycles. These findings conclusively contradict the specialist predator hypothesis. The search for the mechanisms underlying the spectacular dynamics of cyclic vole populations must, therefore, continue.

Ol033 Oli, M., 1999. The chitty effect: a consequence of dynamic energy allocation in a fluctuating environment. Theor. Popul. Biol., 56(3): 293-300.    Ol033.pdf      

Abstract: An important biological feature of cyclic populations of voles and lemmings is phase-related changes in average body mass, with adults in high-density phases being 20-30 \% heavier than those in low-density phases of a cycle. This observation, called the ``Chitty effect,'' is considered to be a ubiquitous feature of cyclic populations. It has been argued that understanding the Chitty effect is fundamental to unraveling the enigma of population cycles. However, there exists no agreement among biologists regarding the causes of the Chitty effect. Here, I propose a simple hypothesis to explain the Chitty effect, based on phase-related, dynamic allocation of energy between reproductive and somatic effort. The essence of the hypothesis is that: (1) reproduction is suppressed in animals born or raised in the later part of the increase phase by environmental factors, including social influences; (2) suppression of reproduction limits the amount of energy that is diverted for reproductive effort, and forces a disproportionately greater amount of surplus power (the energy left after the energetic costs of standard and active metabolism are met) to be allocated for somatic effort; (3) the surplus energy, above and beyond what is required for routine biological activities, will allow continuous growth and deposition of additional body mass, which causes an increase in body mass; and (4) animals grow to a larger size as a population enters the peak density phase, causing an increase in the average body mass. The Chitty effect is predicted to be most pronounced at the late increase or peak phase of a population cycle. Possible causes of reproductive suppression include direct or indirect influences of the environmental factors. The Chitty effect may be a consequence, not a cause, of population cycles in small mammals. (C) 1999 Academic Press.

Ol034 Oleson, K. W. and Lawrence, D. M. and Bonan, G. B. and Flanner, M. G. and Kluzek, E. and Lawrence, P. J. and Levis, S. and Swenson, S. C. and Thornton Aiguo Dai, P. E. and Decker, M. and Dickinson, R. and Feddema, J. and Heald, C. L. and Hoffman, F. and Lamarque, J.-F. and Mahowald, N. and Niu, G.-Y. and Qian, T. and Randerson, J. and Running, S. and Sakaguchi, K. and Slater, A. and Stöckli, R. and Wang, A. and Yang, Z.-L. and Zeng, X. and Zeng, X., 2010. Technical description of version 4.0 of the Community Land Model (CLM). Technical Note, National Center for Atmospheric Research (NCAR), Climate and Global Dynamics Division, Boulder, Col., USA, 266pp.    Ol034.pdf      

Abstract: The purpose of this technical note is to describe the physical parameterizations and numerical implementation of version 4.0 of the Community Land Model (CLM4.0) which is the land surface parameterization used with the Community Atmosphere Model (CAM4.0) and the Community Climate System Model (CCSM4.0). Scientific justification and evaluation of these parameterizations can be found in the referenced scientific papers (section 18). Chapters 1-16 constitute the description of CLM when coupled to CAM or CCSM, while Chapter 17 describes processes that pertain specifically to the operation of CLM in offline mode (uncoupled to an atmospheric model). Chapters 13 and 14 provide brief overviews only of the urban and carbon-nitrogen submodels. Full technical descriptions of these submodels can be found in Oleson et al. (2010) and Thornton et al. (2010, in preparation), respectively. These technical notes and the CLM4 User's Guide together provide the user with the scientific description and operating instructions for CLM.

Ot011 Otto, J. and Raddatz, T. and Claussen, M., 2009. Climate variability-induced uncertainty in mid-holocene atmosphere-ocean-vegetation feedbacks. Geophys. Res. Lett., 36: L23710.    Ot011.pdf      

Abstract: Previous modelling studies have shown that the response of the ocean and the vegetation to mid-Holocene insolation feeds back on the climate. There is less consensus, however, on the relative magnitude of the two feedbacks and the strength of the synergy between them. This discrepancy may arise partly from the statistical uncertainty caused by internal climate variability as the common analysis period is only about a century. Therefore, we have performed an ensemble of centennial-scale simulations using the general circulation model ECHAM5/JSBACH-MPIOM. The direct atmospheric response and the weak atmosphere-vegetation feedback are statistically robust. The synergy is always weak and it changes sign between the ensemble members. The simulations, including a dynamic ocean, show a large variability at sea-ice margins. This variability leads to a sampling error which affects the magnitude of the diagnosed feedbacks. Citation: Otto, J., T. Raddatz, and M. Claussen (2009), Climate variability-induced uncertainty in mid-Holocene atmosphere-ocean-vegetation feedbacks, Geophys. Res. Lett., 36, L23710, doi:10.1029/2009GL041457.

Ow004 Owen-Smith, N., 2004. Functional heterogeneity in resources within landscapes and herbivore population dynamics. Landscape Ecol., 19(7): 761-771.    Ow004.pdf      

Abstract: Large mammalian herbivores are notorious for their propensity towards population irruptions and crashes, yet many herbivore populations remain relatively stable. I explore how resource heterogeneity within landscapes dampens population instability, using a metaphysiological modelling approach considering patch state distributions. Resource heterogeneity is functionally stabilizing through spreading consumption away from preferred resources before these become critically depleted. Lower-quality resources act as a buffer against starvation during critical periods of the seasonal cycle. Enriching resource quality is destabilizing, even if patch diversity is maintained, because food quantity then becomes the limitation. The potential consequences of landscape fragmentation are explored using the Serengeti ecosystem, characterised by broadscale resource gradients, as a hypothetical example. Further insights provided by the model are illustrated with specific examples concerning the effects of patch scales and waterpoint distribution. A metaphysiological modelling approach enables the basic consequences of landscape heterogeneity to be distinguished from further effects that may arise from specific patch scales and configurations, without the distracting detail of spatially explicit models.

Pe044 Perruchoud, D. and Fischlin, A., 1995. The response of the carbon cycle in undisturbed forest ecosystems to climate change: A review of plant-soil models. J. Biogeogr., 22(4/5): 759-774.    Pe044.pdf      

Abstract: We compared six plant-soil models from the literature which describe the C-dynamics in forests and include climatic forcing explicitly. Given the differences in experimental frames of published simulations it was not possible to trace back behaviour deviations to particular model formulations. In order to make consistent projections of the C cycle's response in forests in a changing climate there remains an urgent need to analyse the models from a structural point of view based on quantitative model comparisons under well defined conditions.

Pe057 Perruchoud, D. and Joos, F. and Fischlin, A. and Hajdas, I. and Bonani, G., 1999. Evaluating time scales of carbon turnover in temperate forest soils with radiocarbon data. Global Biogeochem. Cycles, 13(2): 555-573.    Pe057.pdf      

Abstract: Timescales of soil organic carbon (SOC) turnover in forests were investigated with soil radiocarbon data. The C-12/C-14 ratios were measured by accelerated mass spectroscopy on soil sampled from a deciduous temperate forest in Switzerland during 1969-1995. The resulting Delta(14)C values (125-174 parts per thousand) were in line with previously published C-14 soil data. We applied FORCLIM-D, a model of nonliving organic matter decomposition including nine litter and two soil compartments to estimate SOC turnover times for this forest type. Carbon 14 aging in woody vegetation was explicitly accounted for. Parameters were calibrated to match radiocarbon ratios observed for forest soils at Meathop Wood, United Kingdom [Harkness et al., 1986]. We estimated that roughly 50-94% (best estimate, 49%) of foliar litter carbon and 11-74% (73%) of fine root litter carbon are eventually respired as CO2 at Meathop Wood; the rest is transferred to soil humus, where it undergoes further decomposition. Turnover times for the 0-20 cm mineral soil layer ranged from 9-50 years (25 years) for a fast overturning soil compartment comprising 38-74% (68%) of bulk SOC and 155-10,018 years (3,570 years) for a slowly overturning compartment. For the Swiss site, SOC turnover times were in the same range. Parameter uncertainties were correlated and induced by uncertainties in C-14 observations from small-scale spatial inhomogeneities, sample preparation and by lack of reliable C-14 observations for the "prebomb" test period. Model-based estimates of soil organic C turnover derived from C-14 data must be used cautiously since they depend on the underlying model structure: bypassing litter in FORCLIM-D overestimated SOC turnover by a factor of 2.5. Such an error might remain undetected in studies lacking samples from the late 1960s and early 1970s. Thus litter C turnover should be included when estimating SOC turnover in temperate forests from C-14 data.

Pe196 Petty, A. M. and Werner, P. A., 2010. How many buffalo does it take to change a savanna? A response to Bowman et al. (2008). J. Biogeogr., 37(1): 193-195.    Pe196.pdf      

Abstract: Bowman et al. (''Journal of Biogeography'', 2008, 35, 1976--1988) aimed to explain observed increases in woody cover on floodplains and savannas of Kakadu National Park using estimates of buffalo (Bubalus bubalis) density as a causal variable. They found that buffalo were a minor model variable and concluded that buffalo are 'not a major driver of floodplain and eucalypt dynamics'. However, the authors mislabelled the historical density of buffalo on their site, citing a period as high density instead of low density. Further, their results were not contextualized within the substantial body of scientific and historical evidence of the buffalo's strong influence on vegetation in Kakadu. The authors instead postulated three unanalysed drivers of observed patterns of change: fire regime, rainfall and atmospheric CO2. We suggest that further analyses of change in woody vegetation should make use of accurate historical records of grazers as well as available data sets on fire history.

Pe197 Petty, A. M. and Werner, P. A. and Lehmann, C. E. R. and Riley, J. E. and Banfai, D. S. and Elliott, L. P., 2007. Savanna responses to feral buffalo in Kakadu National Park, Australia. Ecol. Monogr., 77(3): 441-463.    Pe197.pdf      

Abstract: Savannas are the major biome of tropical regions, spanning 30% of the Earth's land surface. Tree?:?grass ratios of savannas are inherently unstable and can be shifted easily by changes in fire, grazing, or climate. We synthesize the history and ecological impacts of the rapid expansion and eradication of an exotic large herbivore, the Asian water buffalo (Bubalus bubalus), on the mesic savannas of Kakadu National Park (KNP), a World Heritage Park located within the Alligator Rivers Region (ARR) of monsoonal north Australia. The study inverts the experience of the Serengeti savannas where grazing herds rapidly decpard due to a rinderpest epidemic and then recovered upon disease control. Buffalo entered the ARR by the 1880s, but densities were low until the late 1950s when populations rapidly grew to carrying capacity within a decade. In the 1980s, numbers decpard precipitously due to an eradication program. We show evidence that the rapid population expansion and sudden removal of this exotic herbivore created two ecological cascades by altering ground cover abundance and composition, which in turn affected competitive regimes and fuel loads with possible further, long-term effects due to changes in fire regimes. Overall, ecological impacts varied across a north-south gradient in KNP that corresponded to the interacting factors of precipitation, landform, and vegetation type but was also contingent upon the history of buffalo harvest. Floodplains showed the greatest degree of impact during the period of rapid buffalo expansion, but after buffalo removal, they largely reverted to their prior state. Conversely, the woodlands experienced less visible impact during the first cascade. However, in areas of low buffalo harvest and severe impact, there was little recruitment of juvenile trees into the canopy due to the indirect effects of grazing and high frequency of prescribed fires once buffalo were removed. Rain forests were clearly heavily impacted during the first cascade, but the long term consequences of buffalo increase and removal remain unclear. Due to hysteresis effects, the simple removal of an exotic herbivore was not sufficient to return savanna systems to their previous state.

Po099 Pongratz, J. and Raddatz, T. and Reick, C. H. and Esch, M. and Claussen, M., 2009. Radiative forcing from anthropogenic land cover change since ad 800. Geophys. Res. Lett., 36: L02709.    Po099.pdf      

Abstract: We calculate the radiative forcing (RF) from surface albedo changes over the last millennium applying a recently published, population-based reconstruction of anthropogenic land cover change (ALCC). This study thus allows for the first time to assess anthropogenic effects on climate during the pre-industrial era at high spatial and temporal detail. We find that the RF is small throughout the pre-industrial period on the global scale (negative with a magnitude less than 0.05 W/m(2)) and not strong enough to explain the cooling reconstructed from climate proxies between A. D. 1000 and 1900. For the regional scale, however, our results suggest an early anthropogenic impact on climate: Already in A. D. 800, the surface energy balance was altered by ALCC at a strength comparable to present-day greenhouse gas forcing, e. g., -2.0 W/m(2) are derived for parts of India for that time. Several other regions exhibit a distinct variability of RF as a result of major epidemics and warfare, with RF changes in the order of 0.1 W/m(2) within just one century. Citation: Pongratz, J., T. Raddatz, C. H. Reick, M. Esch, and M. Claussen (2009), Radiative forcing from anthropogenic land cover change since A. D. 800, Geophys. Res. Lett., 36, L02709, doi: 10.1029/2008GL036394.

Pr066 Prentice, I. C. and Farquhar, G. D. and Fasham, M. J. R. and Goulden, M. L. and Heimann, M. and Jaramillo, V. J. and Kheshgi, H. S. and C. Le Quéré, Scholes, R. J. and and Wallace, D. W. R., 2001. The carbon cycle and atmospheric carbon dioxide. In: Houghton, J. T. and Ding, Y. and Griggs, D. J. and Noguer, M. and van der Linden, P. J. and Dai, X. and Maskell, K. and Johnson, C. A. (eds.), Climate change 2001: The scientific basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge a.o., 183-237pp.    Pr066.pdf      
Pr071 Price, B., 2006. Spatio-temporal modelling and analysis of larch bud moth population dynamics in the European Alps. Diss ETH ETH Zurich, Zürich, Switzerland, 220pp.    Pr071.pdf      

Abstract: The larch bud moth (Zeiraphera diniana GN.; Lep., Tortricidae) has caused large-scale defoliation of larch trees across the entire Alpine Arc every 8-10 years since at least Roman times. The temporal dynamics of the larch bud moth and its population cycles have been researched intensively, however the spatial patterns of larch bud moth population have received less attention. Some studies have noted the synchrony of population cycles within valleys, or, at the Alpine arc scale, travelling waves of larch bud moth (as a special case of synchrony). However, accurate quantification of these patterns has not previously been shown and the reasons for such patterns remain unclear. Recent research into synchrony suggests dispersal or regional environmental correlation (the Moran Effect) could result in such patterns of synchrony. Knowledge of spatiotemporal patterns of population dynamics is of general interest to ecologists and important for management and conservation purposes. As ecological field studies with high spatial and temporal resolution and extent are usually prohibitively expensive and time consuming, modelling studies are necessary for the management and understanding of systems over wide spatial and temporal grains and extents. However, knowledge of the appropriate grains and extents at which to model is necessary to achieve usable results. The main aims of this research were to 1) to determine the spatio-temporal dynamics of larch bud moth populations at differing scales and 2) to investigate the influence of spatial data resolution on modelling larch bud moth dynamics and determine an optimum resolution for modelling larch bud moth dynamics in the Upper Engadine valley allowing for a balance between model complexity, output accuracy and simulation time. Through time series analysis, in particular cross-correlation and cross-spectral analysis, we were able to confirm that patterns of synchrony at the valley scale and travelling waves at the Alpine arc scale in population cycles of larch bud moth are present but not consistent across all sites in the Upper Engadine valley. At the Alpine arc scale, waves of larch bud moth travel from west to east across the Alpine arc. Wind-driven dispersal mechanisms in conjunction with a gradient in habitat quality (possibly habitat connectivity) provide a feasible explanation for this phenomenon, whereas the Moran effect does not. At the scale of the Upper Engadine valley, populations of larch bud moth are in close synchrony with one another with the exception of populations in areas to which migration is restricted due to orographical effects. This finding also confirms the hypothesis that migration is driving synchrony at the valley extent rather than the Moran effect. We modelled larch bud moth population dynamics and migration under the same process models at the spatial extent of a single valley (The Upper Engadine valley) but with differing spatial grains: 1. that of the entire valley, 2. that of areas known as `sites' which have an average area of 3.7km2 and are homogeneous with respect to altitude, forest type and aspect, and 3. that of the forest compartment, which have an average area of 25 hectares. We revealed that for the larch bud moth, from these spatial grains, optimum modelling spatial grain is that of the `site'. However, dispersal appears to be more sensitive to wind conditions as influenced by orography at a higher spatial resolution than has been assumed previously. Thus, while larch bud moth populations should only be considered distinct at the `site' level and therefore local dynamics modelled at this spatial grain, modelling of migration processes between the `sites' taking into account orography at a higher resolution would produce more accurate predictions. Comparison of our time series analysis and modelling results revealed that migration is an important causal mechanism for observed patterns of synchrony in larch bud moth populations at the valley scale.

Pr072 Prentice, I. C. and Bondeau, A. and Cramer, W. and Harrison, S. P. and Hickler, T. and Lucht, W. and Sitch, S. and Smith, B. and Sykes, M. T., 2007. Dynamic global vegetation modelling: quantifying terrestrial ecosystem responses to large-scale environmental change. In: Canadell, J. G. and Pataki, D. E. and Pitelka, L. F. (eds.), Terrestrial ecosystems in a changing world. Springer-Verlag, Berlin, 175-192pp.    Pr072.pdf      
Pr110 Prud'homme, B. and Minervino, C. and Hocine, M. and Cande, J. D. and Aouane, A. and Dufour, H. D. and Kassner, V. A. and Gompel, N., 2011. Body plan innovation in treehoppers through the evolution of an extra wing-like appendage. Nature, 473(7345): 83-86.    Pr110.pdf      

Abstract: Body plans, which characterize the anatomical organization of animal groups of high taxonomic rank(1), often evolve by the reduction or loss of appendages (limbs in vertebrates and legs and wings in insects, for example). In contrast, the addition of new features is extremely rare and is thought to be heavily constrained, although the nature of the constraints remains elusive(2-4). Here we show that the treehopper (Membracidae) 'helmet' is actually an appendage, a wing serial homologue on the first thoracic segment. This innovation in the insect body plan is an unprecedented situation in 250 Myr of insect evolution. We provide evidence suggesting that the helmet arose by escaping the ancestral repression of wing formation imparted by a member of the Hox gene family, which sculpts the number and pattern of appendages along the body axis(5-8). Moreover, we propose that the exceptional morphological diversification of the helmet was possible because, in contrast to the wings, it escaped the stringent functional requirements imposed by flight. This example illustrates how complex morphological structures can arise by the expression of ancestral developmental potentials and fuel the morphological diversification of an evolutionary parage.

Ra091 Raupach, M. R. and Marland, G. and Ciais, P. and Le Quéré, C. and Canadell, J. G. and Klepper, G. and Field, C. B., 2007. Global and regional drivers of accelerating CO2 emissions. PNAS, 104(24): 10288-10293.    Ra091.pdf    Ra091_S.pdf      

Abstract: CO2 emissions from fossil-fuel burning and industrial processes have been accelerating at a global scale, with their growth rate increasing from 1.1% y-1 for 1990-1999 to >3% y-1 for 2000-2004. The emissions growth rate since 2000 was greater than for the most fossil-fuel intensive of the Intergovernmental Panel on Climate Change emissions scenarios developed in the late 1990s. Global emissions growth since 2000 was driven by a cessation or reversal of earlier declining trends in the energy intensity of gross domestic product (GDP) (energy/GDP) and the carbon intensity of energy (emissions/energy), coupled with continuing increases in population and per-capita GDP. Nearly constant or slightly increasing trends in the carbon intensity of energy have been recently observed in both developed and developing regions. No region is decarbonizing its energy supply. The growth rate in emissions is strongest in rapidly developing economies, particularly China. Together, the developing and least-developed economies (forming 80% of the world's population) accounted for 73% of global emissions growth in 2004 but only 41% of global emissions and only 23% of global cumulative emissions since the mid-18th century. The results have implications for global equity.

Ra144 Raddatz, T. J. and Reick, C. H. and Knorr, W. and Kattge, J. and Roeckner, E. and Schnur, R. and Schnitzler, K. G. and Wetzel, P. and Jungclaus, J., 2007. Will the tropical land biosphere dominate the climate-carbon cycle feedback during the twenty-first century?. Clim. Dyn., 29(6): 565-574.    Ra144.pdf      

Abstract: Global warming caused by anthropogenic CO2 emissions is expected to reduce the capability of the ocean and the land biosphere to take up carbon. This will enlarge the fraction of the CO2 emissions remaining in the atmosphere, which in turn will reinforce future climate change. Recent model studies agree in the existence of such a positive climate-carbon cycle feedback, but the estimates of its amplitude differ by an order of magnitude, which considerably increases the uncertainty in future climate projections. Therefore we discuss, in how far a particular process or component of the carbon cycle can be identified, that potentially contributes most to the positive feedback. The discussion is based on simulations with a carbon cycle model, which is embedded in the atmosphere/ocean general circulation model ECHAM5/MPI-OM. Two simulations covering the period 1860-2100 are conducted to determine the impact of global warming on the carbon cycle. Forced by historical and future carbon dioxide emissions (following the scenario A2 of the Intergovernmental Panel on Climate Change), they reveal a noticeable positive climate-carbon cycle feedback, which is mainly driven by the tropical land biosphere. The oceans contribute much less to the positive feedback and the temperate/boreal terrestrial biosphere induces a minor negative feedback. The contrasting behavior of the tropical and temperate/boreal land biosphere is mostly attributed to opposite trends in their net primary productivity (NPP) under global warming conditions. As these findings depend on the model employed they are compared with results derived from other climate-carbon cycle models, which participated in the Coupled Climate-Carbon Cycle Model Intercomparison Project (C4MIP).

Ra149 Ranta, E. and Lundberg, P. and Kaitala, V. and Stenseth, N. C., 2002. On the crest of a population wave. Science, 298: 973-974.    Ra149.pdf   

Ra179 Raupach, M. R., 2011. Pinning down the land carbon sink. Nature Clim. Change, 1(3): 148-149.    Ra179.pdf      

Abstract: Over half of all anthropogenic carbon dioxide emissions into the atmosphere are removed naturally by land and ocean carbon sinks. New analysis indicates that the land sink is increasing in some surprising places.

Re171 Reay, D. S. and Dentener, F. and Smith, P. and Grace, J. and Feely, R. A., 2008. Global nitrogen deposition and carbon sinks. Nature Geosci., 1(7): 430-437.    Re171.pdf      

Abstract: Land and ocean uptake of carbon dioxide plays a critical role in determining atmospheric carbon dioxide levels. Future increases in nitrogen deposition have been predicted to increase the size of these terrestrial and marine carbon sinks, but although higher rates of nitrogen deposition might enhance carbon uptake in northern and tropical forests, they will probably have less of an impact on ocean sink strength. Combined, the land and ocean sinks may sequester an additional 10\% of anthropogenic cabon emissions by 2030 owing to increased nitrogen inputs, but a more conservative estimate of 1 to 2\% is more likely. Thus nitrogen-induced increases in the strength of land and ocean sinks are unlikely to keep pace with future increases in carbon dioxide.

Re183 Reich, P. B., 2011. Taking stock of forest carbon. Nature Clim. Change, 1(7): 346-347.    Re183.pdf      

Abstract: Forests take up and store large quantities of carbon. An analysis of inventory data from across the globe suggests that temperate and boreal forests accounted for the majority of the terrestrial carbon sink over the past two decades.

Rh004 Rhoades, D., 1985. Offensive-defensive interactions between herbivores and plants - their relevance in herbivore population-dynamics and ecological theory. Am. Nat., 125(2): 205-238.    Rh004.pdf   
Ro012 Royama, T., 1971. A comparative study of models for predation and parasitism. Res. Popul. Ecol., Suppl. 1: 1-91.    Ro012.pdf      
Ro014 Royama, T., 1978. Do weather factors influence the dynamics of spruce budworm populations?. Bimon. Res. Notes, 34(2 (Mar.,Apr.)): 9-10.    Ro014.pdf      

Ro024 Royama, T., 1981. Fundamental concepts and methodology for the analysis of animal population dynamics, with particular reference to univoltine species. Ecol. Monogr., 51(4): 473-493.    Ro024.pdf   

Abstract: This paper presents some concepts and methodology essential for the analysis of population dynamics of univoltine species. Simple stochastic difference equations, comprised of endogenous and exogenous components, are introduced to provide a basic structure for density-dependent population processes. The endogenous component of a population process is modelled as a function of density in the past p generations, including the most recent. The exogenous component of the process consists of all density-independent components of the ecological factors involved, including enhance variations. The model is called a p^t^h order density-dependent process. For a successful analysis of a population process by the above model, it is important that the process be in a state of statistical equilibrium, or stationarity. The simplest notion of stationarity is introduced, and the average behavior of the process, under this assumption, discussed. The order of density dependence in the population process of a given species depends on its interaction with other species involved in the food web. Considering certain attributes of the food web, in particular the limited number of trophic levels, the pyrmaid of numbers, the linear linkages between closely interacting species, and niche separation among competing species, it is argued that the order of density dependence is probably not much higher than three. A second-order model is perhaps adequate in many practical cases. The dynamics of some lower order density-dependent processes are compared by simulations, with a view to showing the effect of density-dependent and density-independent components at different orders. Several types of density dependence are discussed. If a given factor influencing the temporal variation in density is by itself influenced by density, it is called @'causally density-dependent,@' which may reveal itself by some degree of correlation with density. A density-independent factor, however, may also show some sort of correlation with density in the recent past. This is called @'statistically density-dependent.@' Such statistical density dependence may be due to: (1) spurious correlation, (2) bias in an estimator of the correlation coefficient, (3) autocorrelations in the density-independent factor, and (4) an intriguing mathematical property of the stochastic process. Particularly because of the last two reasons, it is often difficult to distinguish, by correlation method, between causal and statistical density dependence. Distinction also exists between temporal and spatial density dependence, the latter not necessarily implying the involvement of the former. The importance of the distinction between these types of density dependence is discussed in relation to the data analysis and model building. A Statistical analysis of the effect of ecological factors on population dynamics is attempted. Since it is often difficult to determine, by correlation, the causally density-dependent structure of a population process under the influence of some unknown density-independent factors, it is suggested that we reverse the procedure to determine the effect of the density-independent factors first. To confirm the involvement of some suspected density-independent factors in the species dynamics, I propose several methods of correlation between annual fluctuations in some population parameters, such as density, rate of change in density, and their transforms, and those in suitable indices of the suspected factors. Merits, demerits, and limitations of these methods are also discussed. To simplify the arguments, the correlation models are set up first without stage division, and then are elaborated to those in which the whole generation span is divided into several life-cycle stages, so that life table information can be used effectively for the identification of the density-independent factors involved in each stage. A set of life tables of the spruce budworm, Choristoneura fumiferana (Clem.), is analyzed to provide an example of the application of the above concepts and methods. Concluding remarks include some notes on designing life table studies.

Ro029 Royama, T., 1984. Population dynamics of the spruce budworm Choristoneura fumiferana. Ecol. Monogr., 54(4): 429-462.    Ro029.pdf   

Abstract: Using the latest observations, experiments, and theoretical studies, I have reanalyzed spruce budworm data from the Green River Project, and now propose a new interpretation of the population dynamics of the species. Spruce budworm populations in the Province of New Brunswick have been oscillating more or less periodically for the last two centuries, the average period being @?35 yr. Local populations over the province tend to oscillate in unison, though their amplitudes and mean levels are not always the same. The local population process in the spruce bud worm is composed of two major parts, a basic oscillation, and secondary fluctuations about this basic oscillation. The basic oscillation is largely determined by the combined action of several intrinsic (density-dependent) mortality factors during the third to sixth larval instars. These factors include parasitoids and, probably, diseases (e.g., microsporidian infection), and, most important, an intriguing complex of unknown causes, which I term @'the fifth agent@' (a large number of larvae with no clear symptoms died during the population decline in the late 1950s). Other mortality factors, including predation, food shortage, weather, and losses during the spring and fall dispersal of young larvae, are not causes of the basic, universally occurring oscillation. Because of immigration and emigration of egg-carrying moths, the ratio of all eggs laid to the number of locally emerged moths (the E/M ratio, or the apparent oviposition rate) fluctuates widely from year to year but independently of the basic oscillation of density in the local populations that were studied. The fluctuation in this ratio is the main source of the secondary fluctuation in density about the basic oscillation, and is highly correlated with the meteorological conditions that govern the immigration and emigration of moths. The E/M ratio is the major density-independent component of budworm population dynamics. Contrary to common belief, there is no evidence to indicate that invasions of egg-carrying moths from other areas upset the assumed endemic equilibrium state of a local population and trigger outbreaks. Moth invasions can only accelerate an increase in a local population to an outbreak level, but this happens only when the population is already in an upswing phase of an oscillation caused by high survival of the feeding larvae. In other words, the @'seed@' of an outbreak lies in the survival of feeding larvae in the locality, and moth invasions can act only as @'fertilizers.@' The weight of evidence is against the idea that an outbreak occurs in an @'epicenter@' and spreads to the surrounding areas through moth dispersal. Rather, the egg mass survey data in New Brunswick since 1952 favor an alternative explanation. If the trough of a population oscillation in a certain area stays comparatively high, as in central New Brunswick in the 1960s, or if the area is more heavily invaded by egg-carrying moths when the populations in that area are in an upswing phase, these populations might reach an outbreak level slightly ahead of the surrounding populations, all of which are oscillating in unison. If a local population oscillates because of the action of density-dependent factors intrinsic to the local budworm system, it may appear to be difficult to explain why many local populations over a wide area oscillate in unison. However, Moran's (1953) theory shows that density-independent factors (such as weather) that are correlated among localities will bring independently oscillating local populations into synchrony, even if weather itself has no oscillatory trend. I illustrate this with a simple time-series model. The same model also illustrates a principle behind the fact that outbreaks occurred fairly regularly in New Brunswick and Quebec during the past two centuries but rather sporadically in other regions of eastern Canada. Finally, I review the commonly accepted theory of outbreaks based on the dichotomy of endemic and epidemic equilibrium states and argue that the theory does not apply to the spruce budworm system.

Ro132 Royama, T. and MacKinnon, W. E. and Kettela, E. G. and Carter, N. E. and Hartling, L. K., 2005. Analysis of spruce budworm outbreak cycles in New Brunswick, Canada, since 1952. Ecology, 86(5): 1212-1224.    Ro132.pdf      

Abstract: Spruce budworm populations in New Brunswick have been surveyed annually since 1952 by sampling egg masses (later, overwintering larvae) as part of the insecticide application program. Although not designed for an ecological investigation, we extracted as much information from the survey data as we could with respect to several ecological issues. (1) All populations across the province tended to cycle in unison, although three major regions were distinguished by dissimilarity in peak and trough levels. We found that these regional distinctions were a result of random variation in the egg recruitment rate, rather than due to factors associated with comparatively fixed ecoregional (e.g., topographic, climatic, or forest type) characteristics. (2) We found, among all regions, a significant correlation in the rate at which eggs were recruited to each generation, thus providing evidence for the Moran effect as the mechanism underlying population synchrony that caused the province-wide outbreaks. (3) We discuss, with the aid of simulations, the nature and significance of random variations in the egg recruitment rate to explain observed differences in the spatial and temporal patterns of population cycles. Finally, we remark on problems in forecasting.

Ro133 Royama, T., 2005. Moran effect on nonlinear population processes. Ecol. Monogr., 75(2): 277-293.    Ro133.pdf      

Abstract: I investigate the efficacy of the Moran effect as applied to natural population processes. The Moran effect, the correlated density-independent disturbances that bring independently oscillating local populations into synchrony, was originally conceived as an attribute of a linear model system. However, it applies only approximately to natural populations. as they are inherently nonlinear in their density-dependent structure, given that no animal has an unlimited reproductive capacity. The degree of approximation, as measured by the degree of correlation among populations involved, is shown to depend, given the density-dependent structure, on the variances of the random disturbances. In particular, if the unperturbed density-dependent process converges to an equilibrium density, approximation is good when the variances are equal among the populations involved and comparatively small, but it worsens as the variances and their differences increase. For those processes that do not converge, when unperturbed, but exhibit bounded oscillations, the degree of approximation tends to deteriorate considerably, or may practically collapse, even if the disturbances are not large in variance. A sample correlation coefficient is often spurious if the observed population processes to be correlated are highly autocorrelated and limited in length. To detect spuriousness, the density-independent disturbances must somehow be estimated from the data. Three methods (moving-average, linear regression, and nonlinear regression) are considered, and their merits and demerits are discussed. Results of the present investigation are summarized with respect to the interpretations (or diagnoses) of sample cross-correlation functions.

Ro241 Rohani, P. and Wearing, H. and Cameron, T. and Sait, S., 2003. Natural enemy specialization and the period of population cycles. Ecol. Lett., 6(5): 381-384.    Ro241.pdf      

Abstract: The dynamical consequences of multiple-species interactions remain an elusive and fiercely debated topic. Recently, Murdoch and colleagues proposed a general rule for the dynamics of generalist natural enemies: when periodic, they exhibit single generation cycles (SGCs), similar to single species systems. This contrasts markedly with specialists, which tend to show classic (longer period) consumer-resource cycles. Using a well-studied laboratory system, we show that this general rule is contradicted when we consider resource age-structure.

Ro242 Roth, G. A. and Whitford, W. G. and Steinberger, Y., 2009. Small mammal herbivory: Feedbacks that help maintain desertified ecosystems. J. Arid Environ., 73(1): 62-65.    Ro242.pdf      

Abstract: We tested the hypothesis that herbivores contribute to feedbacks maintaining arid ecosystems in a degraded state. We studied small mammal herbivory on a subshrub, broom snakeweed (Gutierrezia sarothrae), and perennial grasses at three sites: (1) ungrazed black grama (Bouteloua eriopoda) grassland; (2) grassland degraded by intense short-duration grazing; and (3) mesquite (Prosopis glandulosa) coppice dunes. Snakeweed was browsed by herbivores primarily during dry winter months. The average percent of G. sarothrae standing crop biomass removed by browsing was 9.2 in ungrazed grassland, 7.4 in intensely grazed grassland, and 4.1 in the dunes. In ungrazed grassland, an average of 12\% of grass cover was harvested by herbivores; in the intensely grazed plots - 80\%. Herbivore exclusion plots showed that jackrabbits (Lepus californicus) were the primary browsers on snakeweed and rodents on grasses and G. sarothrae inflorescences. Rodent removal of G. sarothrae inflorescences allows wind dispersal of seeds in disturbed and desertified areas, thereby increasing abundance of this poisonous shrub. Grass-tiller cutting by rodents provides a strong feedback that may be responsible for keeping the grass cover low on the intensely grazed areas. Jackrabbit pruning has little effect on G. sarothrae abundance at any stage of desertification. (C) 2008 Elsevier Ltd. All rights reserved.

Ru001iw Rundle, H. D. and Nosil, P., 2005. Ecological speciation. Ecol. Lett., 8(3): 336-352.      

Abstract: Ecological processes are central to the formation of new species when barriers to gene flow (reproductive isolation) evolve between populations as a result of ecologically-based divergent selection. Although laboratory and field studies provide evidence that 'ecological speciation' can occur, our understanding of the details of the process is incomplete. Here we review ecological speciation by considering its constituent components: an ecological source of divergent selection, a form of reproductive isolation, and a genetic mechanism linking the two. Sources of divergent selection include differences in environment or niche, certain forms of sexual selection, and the ecological interaction of populations. We explore the evidence for the contribution of each to ecological speciation. Forms of reproductive isolation are diverse and we discuss the likelihood that each may be involved in ecological speciation. Divergent selection on genes affecting ecological traits can be transmitted directly (via pleiotropy) or indirectly (via linkage disequilibrium) to genes causing reproductive isolation and we explore the consequences of both. Along with these components, we also discuss the geography and the genetic basis of ecological speciation. Throughout, we provide examples from nature, critically evaluate their quality, and highlight areas where more work is required.

Sa055 Sarmiento, J. L. and Gruber, N., 2002. Sinks for anthropogenic carbon. Physics Today, 55(8): 30-36.    Sa055.pdf    Sa055_S.pdf      

Abstract: Organic carbon buried in sediments as coal, natural gas, and oil over literally hundreds of millions of years is being consumed by human activities and returned to the atmosphere as carbon dioxide on a time scale of a few centuries. The energy harvested from this transformation of fossil fuels supplies us with electricity, heat, transportation, and industrial power. The clearing of forests for agricultural lands and harvesting of wood, which remove carbon-bearing vegetation, have also added carbon dioxide to the atmosphere, in amounts equivalent to more than half of the fossil fuel source. The carbon dioxide added to the atmosphere by man's activities, and its current fate, is depicted in the carbon cycle diagram shown in figure 1. Because of anthropogenic emissions, atmospheric carbon dioxide has climbed to levels that are presently more than 30% higher than before the industrial revolution, as seen in figure 2.1,2 Indeed, geochemical measurements made on ancient ocean sediments reveal that atmospheric carbon dioxide levels over the past 20 million years were likely never as high they are today.

Sa081 Sabine, C. L. and Heimann, M. and Artaxo, P. and Bakker, D. C. E. and Chen, C. T. A. and Field, C. B. and Gruber, N. and Le Quéré, C. and Prinn, R. G. and Richey, J. E. and Lankao, P. R. and Sathaye, J. A. and Valentini, R., 2004. Current status and past trends of the global carbon cycle. In: Field, C. B. and Raupach, M. R. (eds.), Global Carbon Cycle: Integrating Humans, Climate, and the Natural World. Island Press, Washington, D.C., 17-44pp.    Sa081.pdf   
Sa146 Safranyik, L. and Carroll, A. L. and Regniere, J. and Langor, D. W. and Riel, W. G. and Shore, T. L. and Peter, B. and Cooke, B. J. and Nealis, V. G. and Taylor, S. W., 2010. Potential for range expansion of mountain pine beetle into the boreal forest of North America. Can. Entomol., 142(5): 415-442.    Sa146.pdf    Sa146_S.pdf      

Abstract: The potential for mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), to expand its historical range in North America from west of the continental divide into the eastern boreal forest was assessed on the basis of analyses of the effects of climate and weather on brood development and survival, and key aspects of the interaction of mountain pine beetle with its hosts and associated organisms. Variation in climate suitability and high host susceptibility in the boreal forest create a finite risk of establishment and local persistence of low-level mountain pine beetle populations outside their historical range. Eventually, these populations could become widespread and cause epidemic infestations, creating an ecological pathway eastward through the boreal forest. Such infestations would reduce the commercial value of forests and impose an additional disturbance on native ecological systems.

Scha020 Schaphoff, S. and Lucht, W. and Gerten, D. and Sitch, S. and Cramer, W. and and Prentice, I. C., 2006. Terrestrial biosphere carbon storage under alternative climate projections. Clim. Change, 74(1-3): 97-122.    Scha020.pdf      

Abstract: This study investigates commonalities and differences in projected land biosphere carbon storage among climate change projections derived from one emission scenario by five different general circulation models (GCMs). Carbon storage is studied using a global biogeochemical process model of vegetation and soil that includes dynamic treatment of changes in vegetation composition, a recently enhanced version of the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJDGVM). Uncertainty in future terrestrial carbon storage due to differences in the climate projections is large. Changes by the end of the century range from ?106 to +201 PgC, thus, even the sign of the response whether source or sink, is uncertain. Three out of five climate projections produce a land carbon source by the year 2100, one is approximately neutral and one a sink. A regional breakdown shows some robust qualitative features. Large areas of the boreal forest are shown as a future CO2 source, while a sink appears in the arctic. The sign of the response in tropical and sub-tropical ecosystems differs among models, due to the large variations in simulated precipitation patterns. The largest uncertainty is in the response of tropical rainforests of South America and Central Africa.

Se083 Seidl, R. and Fernandes, P. M. and Fonseca, T. F. and Gillet, F. and Jonsson, A. M. and Merganicova, K. and Netherer, S. and Arpaci, A. and Bontemps, J.-D. and Bugmann, H. and Ramon gonzalez-Olabarria, J. and Lasch, P. and Meredieu, C. and Moreira, F. and Schelhaas, M.-J. and Mohren, F., 2011. Modelling natural disturbances in forest ecosystems: a review. Ecol. Model., 222(4): 903-924.    Se083.pdf      

Abstract: Natural disturbances play a key role in ecosystem dynamics and are important factors for sustainable forest ecosystem management. Quantitative models are frequently employed to tackle the complexities associated with disturbance processes. Here we review the wide variety of approaches to modelling natural disturbances in forest ecosystems, addressing the full spectrum of disturbance modelling from single events to integrated disturbance regimes. We applied a general, process-based framework founded in disturbance ecology to analyze modelling approaches for drought, wind, forest fires, insect pests and ungulate browsing. Modelling approaches were reviewed by disturbance agent and mechanism, and a set of general disturbance modelling concepts was deduced. We found that although the number of disturbance modelling approaches emerging over the last 15 years has increased strongly, statistical concepts for descriptive modelling are still largely prevalent over mechanistic concepts for explanatory and predictive applications. Yet, considering the increasing importance of disturbances for forest dynamics and ecosystem stewardship under anthropogenic climate change, the latter concepts are crucial tool for understanding and coping with change in forest ecosystems. Current challenges for disturbance modelling in forest ecosystems are thus (i) to overcome remaining limits in process understanding, (ii) to further a mechanistic foundation in disturbance modelling, (iii) to integrate multiple disturbance processes in dynamic ecosystem models for decision support in forest management, and (iv) to bring together scaling capabilities across several levels of organization with a representation of system complexity that captures the emergent behaviour of disturbance regimes. (C) 2010 Elsevier B.V. All rights reserved.

Sh114 Sheriff, M. J. and Krebs, C. J. and Boonstra, R., 2010. The ghosts of predators past: population cycles and the role of maternal programming under fluctuating predation risk. Ecology, 91(10): 2983-2994.    Sh114.pdf      

Abstract: Maternal effects may be a major factor influencing the demography of populations. In mammals, the transmission of stress hormones between mother and offspring may play an important role in these effects. Laboratory studies have shown that stressors during pregnancy and lactation result in lifelong programming of the offspring phenotype. However, the relevance of these studies to free-living mammals is unclear. The 10-year snowshoe hare (Lepus americanus) cycle is intimately linked to fluctuating predation pressure and predation risk. The enigma of these cycles is the lack of population growth following the decpar phase, when the predators have virtually all disappeared and the food supply is ample. We have shown that a predator-induced increase in maternal stress hormone levels resulted in a decpar in reproduction. Here we examine population and hormone changes over a four-year period from the increase (2005) to the decpar (2008). We report (1) that an index of maternal stress (fecal corticosteroid metabolite [FCM] concentrations) fluctuates in synchrony with predator density during the breeding season; (2) that maternal FCM levels are echoed in their offspring, and this occurs at a population-wide level; and (3) that higher maternal FCM levels at birth are correlated with an increased responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis in their progeny. Our results show an intergenerational inheritance of stress hormones in a free-ranging population of mammals. We propose that the lack of recovery of reproductive rates during the early low phase of the hare cycle may be the result of the impacts of intergenerational, maternally inherited stress hormones caused by high predation risk during the decpar phase.

Sh115 Shuman, J. K. and Shugart, H. H. and O'Halloran, T. L., 2011. Sensitivity of Siberian larch forests to climate change. Glob. Chang. Biol., 17(7): 2370-2384.    Sh115.pdf      

Abstract: The Northern Hemisphere's boreal forests, particularly the Siberian boreal forest, may have a strong effect on Earth's climate through changes in dominant vegetation and associated regional surface albedo. We show that warmer climate will likely convert Siberia's deciduous larch (Larix spp.) to evergreen conifer forests, and thus decrease regional surface albedo. The dynamic vegetation model, FAREAST, simulates Russian boreal forest composition and was used to explore the feedback between climate change and forest composition at continental, regional, and local scales. FAREAST was used to simulate the impact of changes in temperature and precipitation on total and genus-level biomass at sites across Siberia and the Russian Far East (RFE), and for six high- and low-diversity regions. Model runs with and without European Larch (Larix decidua) included in the available species pool were compared to assess the potential for this species, which is adapted to warmer climate conditions, to mitigate the effects of climate change, especially the shift to evergreen dominance. At the continental scale, when temperature is increased, larch-dominated sites become vulnerable to early replacement by evergreen conifers. At the regional and local scales, the diverse Amur region of the RFE does not show a strong response to climate change, but the low-diversity regions in central and southern Siberia have an abrupt vegetation shift from larch-dominated forest to evergreen-conifer forest in response to increased temperatures. The introduction of L. decidua prevents the collapse of larch in these low-diversity areas and thus mitigates the response to warming. Using contemporary MODIS albedo measurements, we determined that a conversion from larch to evergreen stands in low-diversity regions of southern Siberia would generate a local positive radiative forcing of 5.1 +/- 2.6 W m-2. This radiative heating would reinforce the warming projected to occur in the area under climate change.

Si04ct Sitch, S. and Smith, B. and Prentice, I. C. and Arneth, A. and Bondeau, A. and Cramer, W. and Kaplan, J. O. and Levis, S. and Lucht, W. and Sykes, M. T. and Thonicke, K. and Venevsky, S., 2003. Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ dynamic global vegetation model. Global Change Biol., 9(2): 161-185.    Si04ct.pdf   

Abstract: The Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ) combines process-based, large-scale representations of terrestrial vegetation dynamics and land-atmosphere carbon and water exchanges in a modular framework. Features include feedback through canopy conductance between photosynthesis and transpiration and interactive coupling between these 'fast' processes and other ecosystem processes including resource competition, tissue turnover, population dynamics, soil organic matter and litter dynamics and fire disturbance. Ten plants functional types (PFTs) are differentiated by physiological, morphological, phenological, bioclimatic and fire-response attributes. Resource competition and differential responses to fire between PFTs influence their relative fractional cover from year to year. Photosynthesis, evapotranspiration and soil water dynamics are modelled on a daily time step, while vegetation structure and PFT population densities are updated annually. Simulations have been made over the industrial period both for specific sites where field measurements were available for model evaluation, and globally on a 0.5degrees x 0.5degrees grid. Modelled vegetation patterns are consistent with observations, including remotely sensed vegetation structure and phenology. Seasonal cycles of net ecosystem exchange and soil moisture compare well with local measurements. Global carbon exchange fields used as input to an atmospheric tracer transport model (TM2) provided a good fit to observed seasonal cycles of CO2 concentration at all latitudes. Simulated inter- annual variability of the global terrestrial carbon balance is in phase with and comparable in amplitude to observed variability in the growth rate of atmospheric CO2 . Global terrestrial carbon and water cycle parameters (pool sizes and fluxes) lie within their accepted ranges. The model is being used to study past, present and future terrestrial ecosystem dynamics, biochemical and biophysical interactions between ecosystems and the atmosphere, and as a component of coupled Earth system models.

Si114 Sinclair, A. and Chitty, D. and Stefan, C. and Krebs, C., 2003. Mammal population cycles: evidence for intrinsic differences during snowshoe hare cycles. Can. J. Zool., 81(2): 216-220.    Si114.pdf      

Abstract: Some mammals in high northern latitudes show regular population cycles. In snowshoe hares (Lepus americanus), these occur every 9-10 years. One hypothesis proposes extrinsic causes such as food shortage or predation. The other proposes intrinsic causes through different morphs that alternate between different phases of the cycle. The morphs should differ in behaviour or physiology. This hypothesis predicts that animal parages bred from high and low phases of the population cycle should differ in reproduction and survivorship. In a 16-year breeding program, parages of purebred high-phase female hares had reduced reproductive rates relative to those of purebred low-phase females, resulting in extinction of high-phase parages. Reproductive output decpard with age in high- but not low-phase animals. These parages also differed in longevity and senescence. These results are consistent with the intrinsic hypothesis and suggest a mechanism for alternating population densities that could work synergistically with extrinsic causes like predation and food shortage.

Sm073 Smith, M. J. and Sherratt, J. A. and Lambin, X., 2008. The effects of density-dependent dispersal on the spatiotemporal dynamics of cyclic populations. J. Theor. Biol., 254(2): 264-274.    Sm073.pdf      

Abstract: Density-dependent dispersal occurs throughout the animal kingdom, and has been shown to occur in some taxa whose populations exhibit multi-year population cycles. However, the importance of density-dependent dispersal for the spatiotemporal dynamics of cyclic populations is unknown. We investigated the potential effects of density-dependent dispersal on the properties of periodic travelling waves predicted by two coupled reaction-diffusion models: a commonly used predator-prey model, and a general model of cyclic trophic interactions. We compared the effects of varying the gradient of both positive and negative density-dependent dispersal rates, to varying the ratio of the (constant) dispersal rates of the two interacting populations. Our comparison focussed on the possible range of wave properties, and on the waves generated by landscape obstacles and invasions. In all scenarios that we studied, varying the gradient of density-dependent dispersal has small quantitative effects on the travelling wave properties, relative to the effects of varying the ratio of the diffusion coefficients. (C) 2008 Elsevier Ltd. All rights reserved.

So109 Soja, A. J. and Tchebakova, N. M. and French, N. H. F. and Flannigan, M. D. and Shugart, H. H. and Stocks, B. J. and Sukhinin, A., I. P. E. I. C. F. S. and Jr., I. S. P. W., 2007. Climate-induced boreal forest change: Predictions versus current observations. Global Planet. Change, 56(3-4): 274-296.    So109.pdf      

Abstract: For about three decades, there have been many predictions of the potential ecological response in boreal regions to the currently warmer conditions. In essence, a widespread, naturally occurring experiment has been conducted over time. In this paper, we describe previously modeled predictions of ecological change in boreal Alaska, Canada and Russia, and then we investigate potential evidence of current climate-induced change. For instance, ecological models have suggested that warming will induce the northern and upslope migration of the treepar and an alteration in the current mosaic structure of boreal forests. We present evidence of the migration of keystone ecosystems in the upland and lowland treepar of mountainous regions across southern Siberia. Ecological models have also predicted a moisture-stress-related dieback in white spruce trees in Alaska, and current investigations show that as temperatures increase, white spruce tree growth is declining. Additionally, it was suggested that increases in infestation and wildfire disturbance would be catalysts that precipitate the alteration of the current mosaic forest composition. In Siberia, 7 of the last 9 yr have resulted in extreme fire seasons, and extreme fire years have also been more frequent in both Alaska and Canada. In addition, Alaska has experienced extreme and geographically expansive multi-year outbreaks of the spruce beetle, which had been previously limited by the cold, moist environment. We suggest that there is substantial evidence throughout the circumboreal region to conclude that the biosphere within the boreal terrestrial environment has already responded to the transient effects of climate change. Additionally, temperature increases and warming-induced change are progressing faster than had been predicted in some regions, suggesting a potential non-parar rapid response to changes in climate, as opposed to the predicted slow parar response to climate change. (C) 2006 Elsevier B.V. All rights reserved.

Sta055 Stark, S. and Strommer, R. and Tuomi, J., 2002. Reindeer grazing and soil microbial processes in two suboceanic and two subcontinental tundra heaths. OIKOS, 97(1): 69-78.    Sta055.pdf      

Abstract: In oceanic, nutrient-rich Fermoscandian arctic-alpine tundra heaths, grazing by reindeer has been found to increase herbs and graminoids in relation to dwarf shrubs. In continental lichen heaths in the inland with nutrient-poor conditions, however, slowly decomposable dwarf shrubs are favoured by grazing. According to a hypothesis, by favouring easily decomposing plants in nutrient-rich conditions and slowly decomposing plants in nutrient-poor conditions, herbivory enhances soil nutrient cycling in nutrient-rich and retards it in nutrient-poor areas. We tested this hypothesis by comparing the impact of reindeer grazing on soil C and N mineralization between two oceanic and two continental arctic-alpine tundra heaths. Although soil respiration and microbial metabolic activity were enhanced by grazing in the suboceanic but not in the subcontinental tundra heaths, gross N mineralization rates were higher in the grazed areas in soils from all study sites, indicating that reindeer grazing leads to increased rates of nutrient cycling in both nutrient-poor and nutrient-rich tundra heaths. Thus, in the subcontinental tundra heaths, the increase in soil N concentrations due to mammalian waste products enhances N mineralization rates, even though the organic C quality is not improved by reindeer grazing. There was some site-specific variation in the strength of the reindeer effects on various microbial processes and soil properties, which can be related to spatial variation in grazing intensity and timing, as these factors in turn affect the nutrient sink strength of the vegetation.

Ste095 Stenseth, N., 1978. Is female biased sex-ratio in wood lemming Myopus schisticolor maintained by cyclic inbreeding. OIKOS, 30(1): 83-89.    Ste095.pdf   

Abstract: The hypothesis is developed where the female biased sex ratio in wood lemming Myopus schisticolor (Lillj.), a cyclic microtine, is maintained through evolutionary time by recurrent inbreeding. If the effects, with respect to sex ratio, of inbreeding are stronger than the effects of outbreeding, then the optimal strategy (being favoured by individual selection) would be to produce as many females as possible; the condition is that a sufficient number of males are present to ensure fertilization of all (or most) daughters. This is ensured by producing enough sons and/or by fathers mating with daughters. Some evidence supporting the occurrence of cyclic inbreeding (both sister-brother and daughter-father matings) during large fractions of microtine cycles in general, is outpard. Female biased sex ratio is predicted to be more common among exaggerated cyclic microtines than appreciated at present. One known case that seems to be similar to the situation in the wood lemming is briefly discussed: The arctic lemming Dicrostonyx torquatus (Pall.) in arctic USSR and North America. Studies aimed at producing data for testing the hypothesized occurrence of inbreeding are sorely needed: Microtines should be studied with respect to breeding structure during low and early increase phases. In addition, breeding experiments for analysing the genetic mechanism are needed.

Ste096 Steinbauer, M. and Kriticos, D. and Lukacs, Z. and Clarke, A., 2004. Modelling a forest lepidopteran: phenological plasticity determines voltinism which influences population dynamics. For. Ecol. Manage., 198(1-3): 117-131.    Ste096.pdf      

Abstract: Mizesampela privata is an Australian geometrid moth that is considered to have resource-driven outbreaks. An autumnal oviposition/larval development cycle is considered the ``norm'' in this species, but spring/summer activity has also been observed. This apparent plasticity of phenology and probable concomitant changes in voltinism have not been considered as possible causes of moth outbreaks. We developed GumMoth, a phenological model for M. privata that uses temperature to predict development times of immatures. Photoperiod determines whether individuals undergo direct development or pupal diapause. We used known catch dates of moths (in the same moth-active season or 365-day period) to simulate population phenologies on the Australian mainland (27degrees28'S to 38degrees14'S) and in Tasmania (40degrees54'S to 42degrees57'S). GumMoth successfully simulated phenological patterns that agreed with published records and demonstrated for the first time that multivoltinism is possible in M. privata. In seven paired simulations using dates for first and last moth catches, the earliest moth activity resulted in the pupae of four out of 11 generations undergoing diapause, whereas the latest moth activity resulted in pupae of five out of eight generations undergoing diapause (diapause individuals emerged the following moth-active season). Almost two-thirds of offspring of spring/summer active moths reached adulthood within that same moth-active season (i.e. no delay in development), whereas those of autumn active moths always reached adulthood the following moth-active season (i.e. development was delayed). Records from foresters and in the scientific literature confirmed that the more common autumn phenology is supplemented by spring/summer activity in many localities. At half of these localities, populations that required insecticide control or caused substantial defoliation also developed. Because plantation eucalypts are suitable M. privata hosts for only four to five tree-growth seasons after planting, local moth populations must increase quickly if an outbreak is to occur. We suggest that large populations are more likely when plantations are colonised in the first moth-active season after planting and population growth commences in the spring/summer of each subsequent year. Foresters can use catch dates and regional weather data in GumMoth to estimate the number and phenology of generations of M. privata. This information can be used to assess risk posed by regional populations and thereby adjust future surveillance intensity. (C) 2004 Elsevier B.V. All rights reserved.

Ste097 Steinkamp, K., 2011. Inverse modeling of the sources and sinks of atmospheric CO2: joint constraints from the ocean and atmosphere. Diss. ETH No. ETH Zurich (Swiss Federal Institute of Technology), Zürich, Switzerland, 202pp.    Ste097.pdf

Abstract: This thesis addresses the quantification of carbon dioxide (CO2) exchange between the three major compartments of the earth system: the atmosphere, the land and the ocean. Knowledge about the cycling of carbon among these compartments is crucial, since CO2 is a greenhouse gas and its accumulation in the atmosphere in response to human activities is the primary driver of climate change. Inverse modeling techniques are applied to estimate the carbon exchange, in particular the socalled Bayesian synthesis inversion. This method uses observed concentrations of CO2 and other carbon compounds in the atmosphere and the ocean in conjunction with models of atmospheric and oceanic tracer transport. The observed concentrations are propagated inversely (''back in time'') through the transport models to reconstruct the distribution of CO2 sinks and sources at the atmosphere-surface interface. Sinks and sources (generic: fluxes) are resolved at continental scales and with monthly resolution averaged over time periods of 5 to 10 years between 1980 and 2008, allowing also for the estimation of decadal flux trends. Utilized observational data streams include atmospheric CO2 concentrations from a network of surface stations, concentrations of dissolved inorganic carbon (DIC) in the ocean interior, and differences in the partial pressure of CO2 (pCO2) in the surface ocean and overlying atmospheric layer. Estimated CO2 fluxes and trends are jointly constrained by, and simultaneously consistent with, all data streams. The joint approach allows to address persistent key questions in the field of CO2 flux estimation, such as the strength of the carbon sink in Northern Hemisphere extra-tropical land regions in relation to the tropics: it is shown that the tropics are required to act as net source of carbon to the atmosphere in order to achieve consistency with the observations. A strong net CO2 release from the Amazonian region plays a key role in this regard, especially as it has been persistent over the last three decades and appears robust across several sensitivity experiments. Most of the decadal increase in northern land CO2 uptake is shown to be localized in boreal regions and can partially be attributed to enhanced growing season uptake.

Ste100 Stewart, M. M. and Grosjean, M. and Kuglitsch, F. G. and Nussbaumer, S. U. and von Gunten, L., 2011. Reconstructions of late Holocene paleofloods and glacier length changes in the Upper Engadine, Switzerland (ca. 1450 BC-AD 420). Palaeogeogr. Palaeoclimatol. Palaeoecol., 311(3-4): 215-223.    Ste100.pdf      

Abstract: The relationship between summer-autumn floods in Central Europe and climate warming is poorly constrained by available instrumental, historical, proxy and model data. To investigate this relationship, a complete record of paleofloods, regional glacier length changes (and associated climate phases) and regional glacier advances and retreats (and associated climate transitions) are derived from the varved sediments of Lake Silvaplana (ca. 1450 BC-AD 420; Upper Engadine, Switzerland). In combination, these records provide insight into the behavior of floods (i.e. frequency) under a wide range of climate conditions. Eighty-five paleofloods are identified from turbidites in the sediments of Lake Silvaplana. Regional glacier length changes (and associated cool and/or wet and warm and/or dry climate phases) are inferred from centennial anomalies in the square root of low-pass (LP) filtered Mass Accumulation Rates (MAR(LP)(1/2)). Regional glacier advances and retreats (and associated cooling and/or wetting and warming and/or drying climate transitions) are inferred from centennial trends in MAR. This is the first continuous record of glacier length changes in the Lake Silvaplana catchment for this time period. These data agree with regional records of land-use, glacier activity and lake levels. More frequent turbidites are found during cool and/or wet phases of ca. 1450 BC to AD 420. However, no relationship to climate transitions is discerned. Consistently, June-July-August (JJA) temperatures dating ca. 570 BC-AD 120 are inversely correlated to the frequency of turbidites. The rate that turbidite frequency increases with cooler BA temperatures is not parar. Finally, 130 analogues for a 21st century climate in the Alps between ca. 570 BC-AD 120 (i.e. 50 year windows with a warming trend and average JJA temperature exceeding AD 1950-AD 2000 values from nearby meteo station Sils Maria) are considered. These reveal that turbidites are less frequent than between ca. 1450 BC-AD 420.(C) 2011 Elsevier B.V. All rights reserved.

Sto073 Stoeckli, R. and Lawrence, D. M. and Niu, G.-Y. and Oleson, K. W. and Thornton, P. E. and Yang, Z.-L. and Bonan, G. B. and Denning, A. S. and Running, S. W., 2008. Use of FLUXNET in the community land model development. J. Geophys. Res. G, 113(G1): G01025.    Sto073.pdf      

Abstract: The Community Land Model version 3 (CLM3.0) simulates land-atmosphere exchanges in response to climatic forcings. CLM3.0 has known biases in the surface energy partitioning as a result of deficiencies in its hydrological and biophysical parameterizations. Such models, however, need to be robust for multidecadal global climate simulations. FLUXNET now provides an extensive data source of carbon, water and energy exchanges for investigating land processes, and it encompasses a global range of ecosystem-climate interactions. Data from 15 FLUXNET sites are used to identify and improve model deficiencies. Including a prognostic aquifer, a bare soil evaporation resistance formulation and numerous other changes in the model result in a significantly improved soil hydrology and energy partitioning. Terrestrial water storage increased by up to 300 mm in warm climates and decreased in cold climates. Nitrogen control of photosynthesis is revealed as another missing process in the model. These improvements increase the correlation coefficient of hourly and monthly latent heat fluxes from a range of 0.5-0.6 to the range of 0.7-0.9. RMSE of the simulated sensible heat fluxes decrease by 20-50\%. Primary production is overestimated during the wet season in mediterranean and tropical ecosystems. This might be related to missing carbon-nitrogen dynamics as well as to site-specific parameters. The new model (CLM3.5) with an improved terrestrial water cycle should lead to more realistic land-atmosphere exchanges in coupled simulations. FLUXNET is found to be a valuable tool to develop and validate land surface models prior to their application in computationally expensive global simulations.

Sto083 Stocker, B. D. and Strassmann, K. and Joos, F., 2011. Sensitivity of holocene atmospheric CO2 and the modern carbon budget to early human land use: analyses with a process-based model. Biogeosci., 8(1): 69-88.    Sto083.pdf      

Abstract: A Dynamic Global Vegetation model coupled to a simplified Earth system model is used to simulate the impact of anthropogenic land cover changes (ALCC) on Holocene atmospheric CO2 and the contemporary carbon cycle. The model results suggest that early agricultural activities cannot explain the mid to late Holocene CO2 rise of 20 ppm measured on ice cores and that proposed upward revisions of Holocene ALCC imply a smaller contemporary terrestrial carbon sink. A set of illustrative scenarios is applied to test the robustness of these conclusions and to address the large discrepancies between published ALCC reconstructions. Simulated changes in atmospheric CO2 due to ALCC are less than 1 ppm before 1000AD and 30 ppm at 2004AD when the HYDE3.1 ALCC reconstruction is prescribed for the past 12 000 years. Cumulative emissions of 69 GtC at 1850 and 233 GtC at 2004AD are comparable to earlier estimates. CO2 changes due to ALCC exceed the simulated natural interannual variability only after 1000 AD. To consider evidence that land area used per person was higher before than during early industrialisation, agricultural areas from HYDE3.1 were increased by a factor of two prior to 1700AD (scenario H2). For the H2 scenario, the contemporary terrestrial carbon sink required to close the atmospheric CO2 budget is reduced by 0.5 GtC yr(-1). Simulated CO2 remains small even in scenarios where average land use per person is increased beyond the range of published estimates. Even extreme assumptions for preindustrial land conversion and high per- capita land use do not result in simulated CO2 emissions that are sufficient to explain the magnitude and the timing of the late Holocene CO2 increase.

Sto087 Stoeckli, S. and Hirschi, M. and Spirig, C. and Calanca, P. and Rotach, M. and W. and Samietz, J., 2012. Impact of climate change on voltinism and prospective diapause induction of a global pest insect – Cydia pomonella (l.). PLoS ONE, 7(4): e35723.    Sto087.pdf    Sto087_S.pdf      

Abstract: Global warming will lead to earlier beginnings and prolongation of growing seasons in temperate regions and will have pronounced effects on phenology and life-history adaptation in many species. These changes were not easy to simulate for actual phenologies because of the rudimentary temporal (season) and spatial (regional) resolution of climate model projections. We investigate the effect of climate change on the regional incidence of a pest insect with nearly worldwide distribution and very high potential for adaptation to season length and temperature – the Codling Moth, Cydia pomonella. Seasonal and regional climate change signals were downscaled to the hourly temporal scale of a pest phenology model and the spatial scale of pest habitats using a stochastic weather generator operating at daily scale in combination with a re-sampling approach for simulation of hourly weather data. Under future conditions of increased temperatures (2045–2074), the present risk of below 20% for a pronounced second generation (peak larval emergence) in Switzerland will increase to 70–100%. The risk of an additional third generation will increase from presently 0–2% to 100%. We identified a significant two-week shift to earlier dates in phenological stages, such as overwintering adult flight. The relative extent (magnitude) of first generation pupae and all later stages will significantly increase. The presence of first generation pupae and later stages will be prolonged. A significant decrease in the length of overlap of first and second generation larval emergence was identified. Such shifts in phenology may induce changes in life-history traits regulating the life cycle. An accordingly life-history adaptation in photoperiodic diapause induction to shorter day-length is expected and would thereby even more increase the risk of an additional generation. With respect to Codling Moth management, the shifts in phenology and voltinism projected here will require adaptations of plant protection strategies to maintain their sustainability.

Str047 Strassmann, K. M. and Joos, F. and Fischer, G., 2008. Simulating effects of land use changes on carbon fluxes: past contributions to atmospheric CO2 increases and future commitments due to losses of terrestrial sink capacity. 583-603pp.    Str047.pdf      

Abstract: The impact of land use on the global carbon cycle and climate is assessed. The Bern carbon cycle-climate model was used with land use maps from HYDE3.0 for 1700 to 2000 A.D. and from post-SRES scenarios for this century. Cropland and pasture expansion each cause about hall of the simulated net carbon emissions of 188 Gt C over the industrial period and 1.1 Gt C yr(-1) in the 1990s, implying a residual terrestrial sink of 113 Gt C and of 1.8 Gt C yr(-1), respectively. Direct CO2 emissions due to land conversion as simulated in book-keeping models dominate carbon fluxes due to land use in the past. They are, however, mitigated by 25\% through the feedback of increased atmospheric CO2 stimulating uptake. CO2 stimulated sinks tire largely lost when natural lands are converted. Past land use change has eliminated potential future carbon sinks equivalent to emissions of 80-150 Gt C over this century. They represent a commitment of past land use change, which accounts for 70\% of the future land use flux in the scenarios considered. Pre-industrial land use emissions are estimated to 45 Gt C at most, implying a maximum change in Holocene atmospheric CO2 of 3 ppm. This is not compatible with the hypothesis that early anthropogenic CO2 emissions prevented a new glacial period.

To063 Townsend, S. E. and Newey, S. and Thirgood, S. J. and Haydon, D. T., 2011. Dissecting the drivers of population cycles: interactions between parasites and mountain hare demography. Ecol. Model., 222(1): 48-56.    To063.pdf      

Abstract: There is a growing awareness that cyclic population dynamics in vertebrate species are driven by a complex set of interactions rather than a single causal factor. While theory suggests that direct host-parasite interactions may destabilise population dynamics, the interaction between host and parasite may also influence population dynamics through indirect effects that result in delayed responses to either density or to life-history traits. Using empirical data on mountain hares (Lepus timidus) infected with a nematode parasite (Trichostrongylus retortaeformis), we developed an individual-based model (IBM) that incorporated direct effects and delayed life-history effects (DLHEs) of a macroparasite, alternative transmission mechanisms and seasonality in host population dynamics. The full model describes mean characteristics of observed mountain hare time series and parasite abundance, but by systematically removing model structure we dissect out dynamic influences of DLHEs. The DLHEs were weakly destabilising, increasing the propensity for cyclic dynamics and suggesting DLHEs could be important processes in host-parasite systems. Further, by modifying model structure we identify a strong influence of parasite transmission mechanism on host population stability, and discuss the implications for parasite aggregation mechanisms, host movement and natural geographical variation in host population dynamics. The effect of T. retortaeformis on mountain hares likely forms part of a complex set of interactions that lead to population cycles. (C) 2010 Elsevier B.V. All rights reserved.

Tr046 Tran, J. K. and Ylioja, T. and Billings, R. F. and Regniere, J. and Ayres, M. P., 2007. Impact of minimum winter temperatures on the population dynamics of Dendroctonus frontalis. Ecol. Appl., 17(3): 882-899.    Tr046.pdf   

Abstract: Predicting population dynamics is a fundamental problem in applied ecology. Temperature is a potential driver of short-term population dynamics, and temperature data are widely available, but we generally lack validated models to predict dynamics based upon temperatures. A generalized approach involves estimating the temperatures experienced by a population, characterizing the demographic consequences of physiological responses to temperature, and testing for predicted effects on abundance. We employed this approach to test whether minimum winter temperatures are a meaningful driver of pestilence from Dendroctonus frontalis ( the southern pine beetle) across the southeastern United States. A distance-weighted interpolation model provided good, spatially explicit, predictions of minimum winter air temperatures ( a putative driver of beetle survival). A Newtonian heat transfer model with empirical cooling constants indicated that beetles within host trees are buffered from the lowest air temperatures by; similar to 1-4 degrees C ( depending on tree diameter and duration of cold bout). The life stage structure of beetles in the most northerly outbreak in recent times ( New Jersey) were dominated by prepupae, which were more cold tolerant (by > 3 degrees C) than other life stages. Analyses of beetle abundance data from 1987 to 2005 showed that minimum winter air temperature only explained 1.5% of the variance in interannual growth rates of beetle populations, indicating that it is but a weak driver of population dynamics in the southeastern United States as a whole. However, average population growth rate matched theoretical predictions of a process-based model of winter mortality from low temperatures; apparently our knowledge of population effects from winter temperatures is satisfactory, and may help to predict dynamics of northern populations, even while adding little to population predictions in southern forests. Recent episodes of D. frontalis outbreaks in northern forests may have been allowed by a warming trend from 1960 to 2004 of 3.3 degrees C in minimum winter air temperatures in the southeastern United States. Studies that combine climatic analyses, physiological experiments, and spatially replicated time series of population abundance can improve population predictions, contribute to a synthesis of population and physiological ecology, and aid in assessing the ecological consequences of climatic trends.

Tr055 Tratalos, J. A. and Cheke, R. A. and Healey, R. G. and Stenseth, N. C., 2010. Desert locust populations, rainfall and climate change: insights from phenomenological models using gridded monthly data. Clim. Res., 43(3): 229-239.    Tr055.pdf      

Abstract: Using autocorrelation analysis and autoregressive integrated moving average (ARIMA) modelling, we analysed a time series of the monthly number of 1 grid squares infested with desert locust Schistocerca gregaria swarms throughout the geographical range of the species from 1930-1987. Statistically significant first-and higher-order autocorrelations were found in the series. Although endogenous components captured much of the variance, adding rainfall data improved endogenous ARIMA models and resulted in more realistic forecasts. Using a square-root transformation for the locust data improved the fit. The models were only partially successful when accounting for the dramatic changes in abundance which may occur during locust upsurges and decpars, in some cases successfully predicting these phenomena but underestimating their severity. Better fitting models were also produced when rainfall data were added to models of an equivalent series for desert locust hoppers (nymphs) that incorporated lagged data for locust swarms as independent variables, representing parent generations. The results are discussed in relation to predicting likely changes in desert locust dynamics with reference to potential effects of climate change.

Tu023 P., T. and N., W. S. and P., E. S. and E., K. B. and W., M. W. and A., F. and J., C. and E., M. and J., B. C., 2003. Dynamical effects of plant quality and parasitism on population cycles of larch budmoth. Ecology, 84(5): 1207-1214.    Tu023.pdf      

Abstract: Population cycles have been remarkably resistant to explanation, in part because crucial experiments are rarely possible on appropriate spatial and temporal scales. Here we show how new approaches to nonlinear time-series analysis can distinguish between competing hypotheses for population cycles of larch budmoth in the Swiss Alps: delayed effects of budmoth density on food quality, and budmoth?parasitoid interactions. We reexamined data on budmoth density, plant quality, and parasitism rates. Our results suggest that the effect of plant quality on budmoth density is weak. By contrast, a simple model of budmoth?parasitoid interaction accounts for 90% of the variance in budmoth population growth rates. Thus, contrary to previous studies, we find that parasitoid?budmoth interaction appears to be the dominant factor driving the budmoth cycle.

Tu027 Turchin, P., 2001. Does population ecology have general laws?. OIKOS, 94(1): 17-26.    Tu027.pdf      

Abstract: There is a widespread opinion among ecologists that ecology lacks general laws. In this paper I argue that this opinion is mistaken. Taking the case of population dynamics. I point out that there are several very general law-like propositions that provide the theoretical basis for most population dynamics models that were developed to address specific issues. Some of these foundational principles, like the law of exponential growth. are logically very similar to certain laws of physics (Newton's law of inertia, for example. is almost a direct analogue of exponential growth). [ discuss two other principles (population self-limitation and resource-consumer oscillations), as well as the more elementary postulates that underlie them. None of the ``laws'' that I propose for population ecology are new. Collectively ecologists have been using these general principles in guiding development of their models and experiments since the days of Lotka. Volterra, and Gause.

Tu030 Turchin, P. and Oksanen, L. and Ekerholm, P. and Oksanen, T. and Henttonen, H., 2000. Are lemmings prey or predators?. Nature, 405(6786): 562-565.    Tu030.pdf      

Abstract: Large oscillations in the populations of Norwegian lemmings have mystified both professional ecologists and lay public(1- 3). Ecologists suspect that these oscillations are driven by a trophic mechanism(4,5): either an interaction between lemmings and their food supply, or an interaction between lemmings and their predators. If lemming cycles are indeed driven by a trophic interaction, can we tell whether lemmings act as the resource ('prey') or the consumer ('predator')? In trophic interaction models, peaks of resource density generally have a blunt, rounded shape, whereas peaks of consumer density are sharp and angular. Here we have applied several statistical tests to three lemming datasets and contrasted them with comparable data for cyclic voles, We find that vole peaks are blunt, consistent with their cycles being driven by the interaction with predators. In contrast, the shape of lemming peaks is consistent with the hypothesis that lemmings are functional predators, that is, their cycles are driven by their interaction with food plants. Our findings suggest that a single mechanism, such as interaction between rodents and predators, is unlikely to provide the 'universal' explanation of all cyclic rodent dynamics.

Tu031 Turchin, P. and Berryman, A. A., 2000. Detecting cycles and delayed density dependence: a comment on Hunter & Price (1998). Ecol. Entomol., 25(1): 119-121.    Tu031.pdf      
Tu060 Turchin, P. and Batzli, G., 2001. Availability of food and the population dynamics of arvicopar rodents. Ecology, 82(6): 1521-1534.    Tu060.pdf      

Abstract: Availability of food may play a number of different dynamical roles in rodent-vegetation systems. Consideration of a suite of rodent-vegetation models, ranging from very simple ones to a model of medium complexity tailored to a specific system (brown lemmings ar point Barrow, Alaska, USA), suggested several general principles. If vegetation grows logistically following an herbivory event (a standard assumption of previously advanced models for herbivore-plant interactions), then almost any biologically reasonable combinations of parameters characterizing rodent-vegetation systems would result in population cycles. We argue, however, that the assumption of logistic growth of the food supply may be appropriate for only a few species, such as moss-eating lemmings. The dynamics of food supply for many arvicoline (microtine) rodents may be better described by a ``parar initial regrowth'' model, which exhibits globally stable dynamics. If this is so, quantitative interactions with food supply are unlikely to explain multiannual population cycles for most boreal or temperate voles. The role of food in population dynamics, however, is not limited to its potential to generate cycles. A tritrophic model including vegetation, rodents, and their specialist predators suggests that food limitation may provide direct density dependence needed for sustained oscillations in this system (which is usually modeled by a phenomenological logistic term in the prey equation). We relate the general theory that we developed to one specific system where we have enough data to arrive at reasonable estimates for most of the parameters-brown lemmings at Point Barrow. The Barrow model exhibits oscillations of the approximately correct period and amplitude, thus giving some theoretical support to the food hypothesis. Nevertheless, we suggest that this result should be treated cautiously because key events explaining the population cycle in the model occur during winter, but winter biology of lemmings is still poorly understood.

Tu061 Turkington, R. and John, E. and Watson, S. and Seccombe-Hett, P., 2002. The effects of fertilization and herbivory on the herbaceous vegetation of the boreal forest in north-western canada: a 10-year study. J. Ecol., 90(2): 325-337.    Tu061.pdf      

Abstract: 1 The influence of fertilizer addition and mammalian herbivore exclosures (a 2 x 2 factorial design, with four replicates at each of two sites) on the cover, species composition and diversity of the understorey vegetation of the boreal forest in the south-western Yukon, Canada, were investigated from 1990 to 1999. This was done to test whether vegetation composition was controlled by resource level alone (bottom-up control), herbivory alone (top-down control), or by both (interactive control). 2 The density of the major herbivore, the snowshoe hare, varied 25-fold, declining from 148 km(-2) in 1990 to 8 km(2) in 1994, and increasing to a second peak of 198 km(2) in 1998. 3 In control plots most species were remarkably constant in percent cover. After 10 years, most of the major species showed significant responses to fertilizer with four species increasing (Festuca altaica, Mertensia paniculata, Epilobium angustifolium, and Achillea millefolium), and three declining (Linnaea borealis, Lupinus arcticus, Arctostaphylos uva-ursi). Some species took up to 5 years before a response was detected. 4 Fertilization caused (i) a decpar in the number of species, and species evenness in the community, (ii) a reduction in the proportion of woody species, and (iii) an increase in herbaceous dicotyledons and grasses. 5 The exclusion of herbivores had virtually no impact on the abundance of the vegetation or on species diversity, except in 1990-92 during a decpar from a peak of 148 hares km (2) to 29 hares km(-2). 6 These results suggest that the percentage cover and composition of herbaceous vegetation in the boreal forest are determined almost exclusively by the productivity of the site (bottom-up control) and that the activities of mammalian herbivores may be important only during peaks in hare population densities (interactive control). 7 Results were both species-specific and time-dependent, suggesting that long-term studies are needed to discriminate between long-term responses to treatments and transient phenomena.

Ty004 Tyson, R. and Haines, S. and Hodges, K. E., 2010. Modelling the canada lynx and snowshoe hare population cycle: the role of specialist predators. Theor. Ecol., 3(2): 97-111.    Ty004.pdf      

Abstract: Mathematical models of the snowshoe hare (Lepus americanus) and Canada lynx (Lynx canadensis) population cycles in the boreal forest have largely focused on the interaction between a single specialist predator and its prey. Here, we consider the role that other hare predators play in shaping the cycles, using a predator-prey model for up to three separate specialist predators. We consider the Canada lynx, coyote (Canis latrans) and great horned owl (Bubo virginianus). Our model improves on past modelling efforts in two ways: (1) our model solutions more closely represent the boreal hare and predator cycles with respect to the cycle period, maximum and minimum hare densities and maximum and minimum predator densities for each predator, and (2) our model sheds light on the role each specialist plays in regulation of the hare cycle, in particular, the dynamics of the raptor appear to be crucial for characterising the low hare densities correctly.

Un027 Ungerer, M. and Ayres, M. and Lombardero, M., 1999. Climate and the northern distribution limits of Dendroctonus frontalis Zimmermann (Coleoptera : Scolytidae). J. Biogeogr., 26(6): 1133-1145.    Un027.pdf      

Abstract: The southern pine beetle, Dendroctonus frontalis, is among the most important agents of ecological disturbance and economic loss in forests of the south-eastern United States. We combined physiological measurements of insect temperature responses with climatic analyses to test the role of temperature in determining the northern distribution limits of D. frontalis. Laboratory measurements of lower lethal temperatures and published records of mortality in wild populations indicated that air temperatures of -16 degrees should result in almost 100\% mortality of D. frontalis. The distribution limits for D. frontalis approximate the isopar corresponding to an annual probability of 0.90 of reaching less than or equal to -16 degrees C. Thus, D. frontalis have been found about as far north as they could possibly occur given winter temperature regimes. At latitudes from 39 degrees N (southern Ohio) to 33 degrees N (central Alabama), winter temperatures must evert high mortality on D. frontalis populations in at least one year out of ten. In contrast, we reject the hypotheses that summer temperatures or the distribution of host trees constrain the northern distribution of D. frontalis. Because of the short generation time of D. frontalis, its high dispersal abilities, and the cosmopolitan distribution of suitable host trees, changes in either the mean or variance of minimum annual temperatures could have almost immediate effects on regional patterns of beetle infestations. We estimate that an increase of 3 degrees C in minimum annual temperature could extend the northern distribution limits by 170 km. Increases or decreases in the variance of minimum annual temperatures would further relax climatic constraints on the northern distribution limits of D. frontalis. Results emphasize the ecological importance of spatial and temporal variability in minimum annual temperatures. The physiologically based models provide a tool for guiding land management decisions in forests and illustrate a general approach for predicting the regional effects of climatic patterns on the distribution of organisms.

Va001 Van den Bos, J. and Rabbinge, R., 1976. Simulation of the fluctuations of the grey larch bud moth. Centre for Agricultural Publishing and Documentation, Wageningen, 83pp.
Va124 Van den Bos, H. and Rijsdijk, F. and Rabbinge, R., 1974. A proces simulation model for the explanation of the population dynamics of the Grey larch bud moth Zeiraphera diniana Gn. (Lepidoptera, Tortricidae) in the Upper Engadin valley (Switzerland). Departement of theoretical production ecology and department of entomology, Agricultural University, Wageningen, Wageningen, the Netherlands, 59pp.
Va129 van der Werf, G. R. and Morton, D. C. and DeFries, R. S. and Olivier, J. G. J. and Kasibhatla, P. S. and Jackson, R. B. and Collatz, G. J. and Randerson, J. T., 2009. CO2 emissions from forest loss. Nature Geosci., 2(11): 737-738.    Va129.pdf    Va129_S.pdf    Va129_S2.pdf      

Abstract: Deforestation is the second largest anthropogenic source of carbon dioxide to the atmosphere, after fossil fuel combustion. Following a budget reanalysis, the contribution from deforestation is revised downwards, but tropical peatlands emerge as a notable carbon dioxide source.

Va140 Valtonen, A. and Ayres, M. P. and Roininen, H. and Poyry, J. and Leinonen, R., 2011. Environmental controls on the phenology of moths: predicting plasticity and constraint under climate change. Oecologia, 165(1): 237-248.    Va140.pdf      

Abstract: Ecological systems have naturally high interannual variance in phenology. Component species have presumably evolved to maintain appropriate phenologies under historical climates, but cases of inappropriate phenology can be expected with climate change. Understanding controls on phenology permits predictions of ecological responses to climate change. We studied phenological control systems in Lepidoptera by analyzing flight times recorded at a network of sites in Finland. We evaluated the strength and form of controls from temperature and photoperiod, and tested for geographic variation within species. Temperature controls on phenology were evident in 51\% of 112 study species and for a third of those thermal controls appear to be modified by photoperiodic cues. For 24\% of the total, photoperiod by itself emerged as the most likely control system. Species with thermal control alone should be most immediately responsive in phenology to climate warming, but variably so depending upon the minimum temperature at which appreciable development occurs and the thermal responsiveness of development rate. Photoperiodic modification of thermal controls constrains phenotypic responses in phenologies to climate change, but can evolve to permit local adaptation. Our results suggest that climate change will alter the phenological structure of the Finnish Lepidoptera community in ways that are predictable with knowledge of the proximate physiological controls. Understanding how phenological controls in Lepidoptera compare to that of their host plants and enemies could permit general inferences regarding climatic effects on mid- to high-latitude ecosystems.

Ve219 Verschoor, A. and Vos, M. and van der Stap, I., 2004. Inducible defences prevent strong population fluctuations in bi- and tritrophic food chains. Ecol. Lett., 7(12): 1143-1148.    Ve219.pdf      

Abstract: Recent theoretical work (Vos et al. 2004) predicts that inducible defences prevent strong population fluctuations under high levels of nutrient enrichment. Here we evaluate this model prediction and show that inducible defences in algae stabilize the dynamics of experimentally assembled bi- and tritrophic planktonic food chains. At high phosphorus levels, we observed strong population fluctuations in all food chains with undefended algae. These fluctuations did not occur when algae had inducible defences. At low phosphorus levels, we observed deterministic consumer extinctions, as predicted by stoichiometric theory. Our study thus shows that both biotically and abiotically induced changes in algal food quality affect the stability and persistence of planktonic food chains.

Wa115 Wagner, A. and Woodward, F. I. and Mulligan, M. and Hewitt, C. N., 1998. Vegetation-climate feedbacks in a greenhouse world - Discussion. Phil. Trans. R. Soc. Lond. B, 353(1365): 38-39.    Wa115.pdf      

Abstract: The potential for feedbacks between terrestrial vegetation, climate, and the atmospheric CO2 partial pressure have been addressed by modelling. Previous research has established that under global warming and CO2 enrichment, the stomatal conductance of vegetation tends to decrease, causing a warming effect on top of the driving change in greenhouse warming. At the global scale, this positive feedback is ultimately changed to a negative feedback through changes in vegetation structure. In spatial terms this structural feedback has a variable geographical pattern in terms of magnitude and sign. At high latitudes, increases in vegetation leaf area index (LAI) and vegetation height cause a positive feedback, and warming through reductions in the winter snow-cover albedo. At lower latitudes when vegetation becomes more sparse with warming, the higher albedo of the underlying soil leads to cooling. However, the largest area effects are of negative feedbacks caused by increased evaporative cooling with increasing LAI. These effects do not include feedbacks on the atmospheric CO2 concentration, through changes in the carbon cycle of the vegetation. Modelling experiments, with biogeochemical, physiological and structural feedbacks on atmospheric CO2, but with no changes in precipitation, ocean activity or sea ice formation, have shown that a consequence of the CO2 fertilization effect on vegetation will be a reduction of atmospheric CO2 concentration, in the order of 12% by the year 2100 and a reduced global warming by 0.7$\,^{\circ}$C, in a total greenhouse warming of 3.9$\,^{\circ}$C.

Wa166 Wanner, H. and Beer, J. and Bütikofer, J. and Crowley, T. J. and Cubasch, U. and Flückiger, J. and Goosse, H. and Grosjean, M. and Joos, F. and Kaplan, J. O. and Küttel, M. and Müller, S. A. and Prentice, I. C. and Solomina, O. and Stocker, T. F. and Tarasov, P. and Wagner, M. and Widmann, M., 2008. Mid- to Late Holocene climate change: an overview. Quaternary Sci. Rev., 27(19-20): 1791--1828.    Wa166.pdf      

Abstract: The last 6000 years are of particular interest to the understanding of the Earth System because the boundary conditions of the climate system did not change dramatically (in comparison to larger glacial--interglacial changes), and because abundant, detailed regional palaeoclimatic proxy records cover this period. We use selected proxy-based reconstructions of different climate variables, together with state-of-the-art time series of natural forcings (orbital variations, solar activity variations, large tropical volcanic eruptions, land cover and greenhouse gases), underpinned by results from General Circulation Models (GCMs) and Earth System Models of Intermediate Complexity (EMICs), to establish a comprehensive explanatory framework for climate changes from the Mid-Holocene (MH) to pre-industrial time. The redistribution of solar energy, due to orbital forcing on a millennial timescale, was the cause of a progressive southward shift of the Northern Hemisphere (NH) summer position of the Intertropical Convergence Zone (ITCZ). This was accompanied by a pronounced weakening of the monsoon systems in Africa and Asia and increasing dryness and desertification on both continents. The associated summertime cooling of the NH, combined with changing temperature gradients in the world oceans, likely led to an increasing amplitude of the El Niño Southern Oscillation (ENSO) and, possibly, increasingly negative North Atlantic Oscillation (NAO) indices up to the beginning of the last millennium. On decadal to multi-century timescales, a worldwide coincidence between solar irradiance minima, tropical volcanic eruptions and decadal to multi-century scale cooling events was not found. However, reconstructions show that widespread decadal to multi-century scale cooling events, accompanied by advances of mountain glaciers, occurred in the NH (e.g., in Scandinavia and the European Alps). This occurred namely during the Little Ice Age (LIA) between AD 1350 and 1850, when the lower summer insolation in the NH, due to orbital forcing, coincided with solar activity minima and several strong tropical volcanic eruptions. The role of orbital forcing in the NH cooling, the southward ITCZ shift and the desertification of the Sahara are supported by numerous model simulations. Other simulations have suggested that the fingerprint of solar activity variations should be strongest in the tropics, but there is also evidence that changes in the ocean heat transport took place during the LIA at high northern latitudes, with possible additional implications for climates of the Southern Hemisphere (SH).

Wa201 Wardle, D. and Barker, G. and Yeates, G. and Bonner, K. and Ghani, A., 2001. Introduced browsing mammals in New Zealand natural forests: aboveground and belowground consequences. Ecol. Monogr., 71(4): 587-614.    Wa201.pdf      

Abstract: Forest dwelling browsing mammals, notably feral goats and deer, have been introduced to New Zealand over the past 220 years; prior to this such mammals were absent from New Zealand. The New Zealand forested landscape, therefore, presents an almost unique opportunity to determine the impacts of introduction of an entire functional group of alien animals to a habitat from which that group was previously absent. We sampled 30 long-term fenced exclosure plots in indigenous forests throughout New Zealand to evaluate community- and ecosystem-level impacts of introduced browsing mammals, emphasizing the decomposer subsystem. Browsing mammals often significantly altered plant community composition, reducing palatable broad-leaved species and promoting other less palatable types. Vegetation density in the browse layer was also usually reduced. Although there were some small but statistically significant effects of browsing on some measures of soil quality across the 30 locations, there were no consistent effects on components of the soil microfood web (comprising microflora and nematodes, and spanning three consumer trophic levels); while there were clear multitrophic effects of browsing on, this food web for several locations, comparable numbers of locations showed stimulation and inhibition of biomasses or populations of food web components. In contrast, all microarthropod and macrofaunal groups were consistently adversely affected by browsing, irrespective of trophic position. Across the 30 locations, the magnitude of response of the dominant soil biotic groups to browsing mammals (and hence their resistance to browsers) was not correlated with the magnitude of vegetation response to browsing but was often strongly related to a range of other variables, including macroclimatic, soil nutrient, and tree stand properties. There were often strong significant effects of browsing mammals on species composition of the plant community, species composition of leaf litter in the litter layer, and composition of various litter-dwelling faunal groups. Across the 30 locations, the magnitude of browsing mammal effects on faunal community composition was often correlated with browser effects on litter layer leaf species composition but never with browser effects on plant community composition. Browsing mammals usually reduced browse layer plant diversity and often also altered habitat diversity in the litter layer and diversity of various soil faunal groups. Across the 30 locations, the magnitude of browser effects on diversity of only one faunal group, humus-dwelling nematodes, was correlated with browser effects on plant diversity. However, browser effects on diversity of diplopods and gastropods were correlated with browser effects on habitat diversity of the litter layer. Reasons for the lack of unidirectional relationships across locations between effects of browsers on vegetation community attributes and on soil invertebrate community attributes are discussed. Browsing mammals generally did not have strong effects on C mineralization but did significantly influence soil C and N storage on an areal basis for several locations. However the direction of these effects was idiosyncratic and presumably reflects different mechanisms by which browsers affect soil processes. While our study did not support hypotheses predicting consistent negative effects of browsing mammals on the decomposer subsystem through promotion of plant species with poorer litter quality, our results still show that the introduction of these mammals to New Zealand has caused far-ranging effects at both the community and ecosystem levels of resolution, with particularly adverse effects for indigenous plant communities and populations of most groups of litter-dwelling mesofauna and macrofauna.

We154 Wellington, W. G. and Fettes, J. J. and Belyea, R. M. and Turner, K. B., 1950. Physical and biological indicators of the development of outbreaks of the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae). Can. J. Res. D Zool. Sci., 28d(6): 308--331.    We154.pdf   

Abstract: Biological and meteorological records were examined for periods when outbreaks of the spruce budworm, Choristoneura fumiferana (Clem.), were known to have occurred in northeastern North America. The survey showed that the following significant events occurred during the period of three to four years preceding an outbreak. Decreasing annual numbers of low pressure centers passed over the area in which the outbreak later occurred. Therefore, the outbreak began at a time of decreased or minimal storminess. Drought occurred, chiefly in June and July, but also occasionally in spring and autumn. Annual increments of host trees on dry sites declined. Outbreaks of the forest tent caterpillar, Malacosoma disstria Hbn., occurred, particularly in Ontario. These events, in aggregate, occurred so consistently before spruce budworm outbreaks that they have future predictive value. In addition, they reinforce some suggestions made by earlier authors and suggest modifications of hypotheses concerning the behavior of developing populations of the spruce budworm.

Wi021 Williams, K. S. and Myers, J. H., 1984. Previous herbivore attack of red alder may improve food quality for fall webworm larvae. Oecologia, 63(2): 166-170.    Wi021.pdf      

Abstract: Three hypotheses of insect-plant interactions were tested by rearing fall webworm larvae in the laboratory on foliage from red alder trees with different histories of western tent caterpillar herbivory. Fall webworm larvae raised on foliage from trees which had been attacked previously for two summers by moderate densities of western tent caterpillars grew faster and attained heavier pupal weights than did those fed foliage from unattacked trees. This contradicts the hypothesis that moderate levels of previous herbivory induces the production of plant defensive chemicals in red alders. Growth of webworms, when fed foliage from unattacked trees adjacent to alders that were attacked by fall webworm larvae, was the same as when fed foliage from trees isolated by distance from attacked trees. This contradicts the hypothesis that attacked trees stimulate the production of defensive chemicals in neigh-boring trees. Young and mature alder foliage was equally good for fall webworm growth and survival, and foliage from trees heavily attacked by both fall webworm and western tent caterpillars for three years produced slow growth rates and small pupal sizes. This supports the hypothesis that continued heavy insect attack can cause the deterioration of the food quality of attacked trees.

Wi291 Williams, D. and Liebhold, A., 2000. Spatial synchrony of spruce budworm outbreaks in eastern north america. Ecology, 81(10): 2753-2766.    Wi291.pdf      

Abstract: We investigated the spatial synchrony of outbreaks of the spruce budworm, Choristoneura fumiferana, over much of its outbreak range in eastern North America during the period 1945-1988. Spatial synchrony decreased with distance between local populations and approached zero near 2000 km. Investigation of the synchrony of local population time series with cluster analysis revealed a pattern of geographically distinct blocks of clusters oriented along an east-west axis. Spatial synchrony also was identified in monthly temperature and precipitation time series at 18 weather stations over the same time period and geographical range as the spruce budworm outbreaks. Cross correlations decreased pararly with distance between stations and approached zero near 3000 km and 1800 km, respectively. We developed a spatially explicit lattice model for a single species occupying multiple patches. Within patches, the model had first order logistic dynamics, and patches were linked by dispersal that depended upon their separation distances. Both local and regional stochasticity (i.e., a Moran effect) were present. The modeled lattice had the same spatial configuration as the outbreak region to facilitate investigating the relative effects of a Moran effect and dispersal on spatial synchrony. Simulations with and without a simple region-wide Moran effect and three levels of dispersal did not produce the decrease in spatial synchrony with distance observed with spruce budworm time series. However, when run at the highest dispersal rate, those simulations produced cluster maps similar to that observed for spruce budworm defoliation. Simulations with a spatially autocorrelated disturbance that had either zero or high local variability and three levels of dispersal produced decreases in spatial synchrony with distance similar to that observed in the historical data. When run at the highest dispersal rate, simulations yielded cluster maps similar to the cluster map for defoliation. We discuss the potential significance of the spatially autocorrelated disturbance factor in understanding regional insect outbreaks. We also consider the plausibility of dispersal rates used in our simulations. We suggest in conclusion that spruce budworm outbreaks were synchronized by a combination of a spatially autocorrelated Moran effect and a high dispersal rate.

Wi292 Williams, D. and Liebhold, A., 1995. Herbivorous insects and global change: potential changes in the spatial distribution of forest defoliator outbreaks. J. Biogeogr., 22(4-5): 665-671.    Wi292.pdf      

Abstract: The geographical ranges and the spatial extent of outbreaks of herbivorous species are likely to shift with climatic change. We investigated potential changes in spatial distribution of outbreaks of the western spruce budworm, Choristoneura occidentalis Freeman, in Oregon, U.S.A. and the gypsy moth, Lymantria dispar (L.), in Pennsylvania, U.S.A. using maps of historical defoliation, climate and forest composition in a geographic information system. Maps of defoliation frequency were assembled using historical aerial reconnaissance data. Maps of monthly means of daily temperature maxima and minima and of monthly precipitation averaged over 30 years were developed using an interpolation technique. All maps were at a spatial resolution of 2 x 2 km. Relationships between defoliation status and the environmental variables were modelled using a parar discriminant function. Five climatic change scenarios were investigated: an increase of 2 degrees C, a 2 degrees increase with an increase of 0.5 mm per day in precipitation, a 2 degrees C increase with an equivalent decrease in precipitation, and equilibrium projections of temperature and precipitation by two general circulation models (GCMs) at doubled CO2. With an increase in temperature alone, the projected defoliated area decreased relative to ambient conditions for the budworm and increased slightly for the gypsy moth. With an increase in temperature and precipitation the defoliated area increased for both species. Conversely, the defoliated area decreased for both when temperature increased and precipitation decreased. Results for the GCM scenarios contrasted sharply. For the Geophysical Fluids Dynamics Laboratory model, defoliation by budworm was projected to cover Oregon completely, whereas no defoliation was projected by gypsy moth in Pennsylvania. For the Goddard Institute for Space Studies model, defoliation disappeared completely for the budworm and slightly exceeded that under ambient conditions for the gypsy moth. The results are discussed :in terms of potential changes in forest species composition.

Wi293 Williams, D. and Liebhold, A., 1995. Detection of delayed density-dependence - effects of autocorrelation in an exogenous factor. Ecology, 76(3): 1005-1008.    Wi293.pdf      
Wi294 Williams, D. and Liebhold, A., 1997. Detection of delayed density dependence: reply. Ecology, 78(1): 320-322.    Wi294.pdf      
Wo045 Woodward, F. I. and Lomas, M. R. and Betts, R. A., 1998. Vegetation-climate feedbacks in a greenhouse world. Phil. Trans. R. Soc. Lond. B, 353(1365): 29-38.    Wo045.pdf      

Abstract: The potential for feedbacks between terrestrial vegetation, climate, and the atmospheric CO2 partial pressure have been addressed by modelling. Previous research has established that under global warming and CO2 enrichment, the stomatal conductance of vegetation tends to decrease, causing a warming effect on top of the driving change in greenhouse warming. At the global scale, this positive feedback is ultimately changed to a negative feedback through changes in vegetation structure. In spatial terms this structural feedback has a variable geographical pattern in terms of magnitude and sign. At high latitudes, increases in vegetation leaf area index (LAI) and vegetation height cause a positive feedback, and warming through reductions in the winter snow-cover albedo. At lower latitudes when vegetation becomes more sparse with warming, the higher albedo of the underlying soil leads to cooling. However, the largest area effects are of negative feedbacks caused by increased evaporative cooling with increasing LAI. These effects do not include feedbacks on the atmospheric CO2 concentration, through changes in the carbon cycle of the vegetation. Modelling experiments, with biogeochemical, physiological and structural feedbacks on atmospheric CO2, but with no changes in precipitation, ocean activity or sea ice formation, have shown that a consequence of the CO2 fertilization effect on vegetation will be a reduction of atmospheric CO2 concentration, in the order of 12% by the year 2100 and a reduced global warming by 0.7 degrees C, in a total greenhouse warming of 3.9 degrees C.

Wo127 Wolda, H., 1989. The equilibrium concept and density dependence tests - what does it all mean. Oecologia, 81(3): 430-432.    Wo127.pdf      

Abstract: Tests of density dependent regulation of population size depend on the concept of equilibrium population size. Such an equilibrium is a purely theoretical construct whose existence in the field is debatable and whose value cannot be measured. An equilibrium is supposed to fluctuate in time, but the extent of the fluctuations relative to those of the population size is unknowable. It is impossible to separate a fluctuating population size from a fluctuating equilibrium value and from fluctuating deviations from an equilibrium value. Because it cannot be determined whether a given population size is above, at, or below equilibrium, the course of population size in unpredictable and density dependence tests cannot be expected to produce useful results. Stabilization tests may provide a more useful alternative.

Wo128 Wolda, H., 1991. The usefulness of the equilibrium concept in population dynamics - A reply to Berryman. Oecologia, 86: 144-145.   
Wu017 Wu, Y. and Price, B. and Isenegger, D. and Fischlin, A. and Allgower, B. and Nuesch, D., 2006. Real-time 4D visualization of migratory insect dynamics within an integrated spatiotemporal system. Ecol. Informatics, 1(2): 179-187.    Wu017.pdf      

Abstract: This paper presents a new approach of spatiotemporally visualizing the simulation output of migratory insect dynamics and resultant vegetation changes in real-time. The visualization is capable of displaying simulated ecological phenomena in an intuitive manner, which allows research results to be easily understood by a wide range of users. In order to design a fast and efficient visualization technique, a simplified mathematical model is applied to intelligibly represent migrating groups of insects. In addition, impostors are used to accelerate rendering processes. The presented visualization method is implemented in an integrated spatiotemporal analysis system, which models, simulates and analyzes ecological phenomena such as insect migration through time at a variety of spatial resolutions.

Yi004 Yi, C. and Ricciuto, D. and Li, R. and Wolbeck, J. and Xu, X. and Nilsson, M. and Aires, L. and Albertson, J. D. and Ammann, C. and Arain, M. A. and de Araujo, A. C. and Aubinet, M. and Aurela, M. and Barcza, Z. and Barr, A. and Berbigier, P. and Beringer, J. and Bernhofer, C. and Black, A. T. and Bolstad, P. V, B. F. C. and Broadmeadow, M. S. J. and Buchmann, N. and Burns, S. P. and Cellier, P. and Chen, J. and Chen, J. and Ciais, P. and Clement, R. and Cook, B. D. and Curtis, P. S. and Dail, D. B. and Dellwik, E. and Delpierre, N. and Desai, A. R. and Dore, S. and Dragoni, D. and Drake, B. G. and Dufrene, E. and Dunn, A. and Elbers, J. and Eugster, W. and Falk, M. and Feigenwinter, C. and Flanagan, L. B. and Foken, T. and Frank, J. and Fuhrer, J. and Gianelle, D. and Goldstein, A. and Goulden, M. and Granier, A. and Gruenwald, T. and Gu, L. and Guo, H. and Hammerle, A. and Han, S. and Hanan, N. P. and Haszpra, L. and Heinesch, B. and Helfter, C. and Hendriks, D. and Hutley, L. B. and Ibrom, A. and Jacobs, C. and Johansson, T. and Jongen, M. and Katul, G. and Kiely, G. and Klumpp, K. and Knohl, A. and Kolb, T. and Kutsch, W. L. and Lafleur, P. and Laurila, T. and Leuning, R. and Lindroth, A. and Liu, H. and Loubet, B. and Manca, G. and Marek, M. and Margolis, H. A. and Martin, T. A. and Massman, W. J. and Matamala, R. and Matteucci, G. and McCaughey, H. and Merbold, L. and Meyers, T. and Migliavacca, M. and Miglietta, F. and Misson, L. and Moelder, M. and Moncrieff, J. and Monson, R. K. and Montagnani, L. and Montes-Helu, M. and Moors, E. and Moureaux, C. and Mukelabai, M. M. and Munger, J. W. and Myklebust, M. and Nagy, Z. and Noormets, A. and Oechel, W. and Oren, R. and Pallardy, S. G. and Kyaw, T. P. U. and Pereira, J. S. and Pilegaard, K. and Pinter, K. and Pio, C. and Pita, G. and Powell, T. L. and Rambal, S. and Randerson, J. T. and von Randow, C. and Rebmann, C. and Rinne, J. and Rossi, F. and Roulet, N. and Ryel, R. J. and Sagerfors, J. and Saigusa, N. and Sanz, M. J. and Mugnozza, G.-S. and Schmid, H. P. and Seufert, G. and Siqueira, M. and Soussana, J.-F. and Starr, G. and Sutton, M. A. and Tenhunen, J. and Tuba, Z. and Tuovinen, J.-P. and Valentini, R. and Vogel, C. S. and Wang, J. and Wang, S. and Wang, W. and Welp, L. R. and Wen, X. and Wharton, S. and Wilkinson, M. and Williams, C. A. and Wohlfahrt, G. and Yamamoto, S. and Yu, G. and Zampedri, R. and Zhao, B. and Zhao, X., 2010. Climate control of terrestrial carbon exchange across biomes and continents. Environ. Res. Lett., 5(3): 034007.    Yi004.pdf      

Abstract: Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net ecosystem exchange of carbon (NEE) and climate factors as measured using the eddy covariance method at 125 unique sites in various ecosystems over six continents with a total of 559 site-years. We find that NEE observed at eddy covariance sites is (1) a strong function of mean annual temperature at mid-and high-latitudes, (2) a strong function of dryness at mid-and low-latitudes, and (3) a function of both temperature and dryness around the mid-latitudinal belt (45 degrees N). The sensitivity of NEE to mean annual temperature breaks down at similar to 16 degrees C (a threshold value of mean annual temperature), above which no further increase of CO2 uptake with temperature was observed and dryness influence overrules temperature influence.

Yo004 Yoshida, T. and Jones, L. E. and Ellner, S. P. and Fussmann, G. F. and Hairston, N. G., 2003. Rapid evolution drives ecological dynamics in a predator-prey system. Nature, 424(6946): 303-306.    Yo004.pdf      

Abstract: Ecological and evolutionary dynamics can occur on similar timescales(1-7). However, theoretical predictions of how rapid evolution can affect ecological dynamics(8) are inconclusive and often depend on untested model assumptions(8). Here we report that rapid prey evolution in response to oscillating predator density affects predator-prey (rotifer-algal) cycles in laboratory microcosms. Our experiments tested explicit predictions from a model for our system that allows prey evolution(9). We verified the predicted existence of an evolutionary tradeoff between algal competitive ability and defence against consumption, and examined its effects on cycle dynamics by manipulating the evolutionary potential of the prey population. Single-clone algal cultures (lacking genetic variability) produced short cycle periods and typical quarter- period phase lags between prey and predator densities, whereas multi-clonal (genetically variable) algal cultures produced long cycles with prey and predator densities nearly out of phase, exactly as predicted. These results confirm that prey evolution can substantially alter predator-prey dynamics, and therefore that attempts to understand population oscillations in nature(10,11) cannot neglect potential effects from ongoing rapid evolution.

Yu003 Yu, G. and Shen, H. and Liu, J., 2009. Impacts of climate change on historical locust outbreaks in China. J. Geophys. Res. D, 114: D18104.    Yu003.pdf      

Abstract: To probe if greenhouse-effected climate warming strengthens severe locust outbreaks that would cause continental-scale crop failures in China, we studied their statistical relationships in history and examined the impacts of climate change on the long-term locust outbreaks. According to analysis for interannual time series during the past 100 years, the most severe locust outbreak years were in the warm-dry years with warm-dry summers and warm-wet winters in the Yellow River-Haihe River region, northern China, and warm-wet years with warm-wet springs in the Yangtze River-Huihe River region, southern China. Checking wavelet-analyzed variance series, these interannual time scale synchronous changes with 2-10 periodicity years were 58-60\% among the total locust outbreak years of the past 1000 years. Locust outbreak correlation analysis with decadal time scale temperature proxy and general circulation model-simulated climate during the past 1000 years showed significant correlations in warm-winter-half years and in warm-dry May-June and annual means in the northern region (p < 0.05), where p is probability, and in warm years and warm-dry August-September years in the southern region (p < 0.10), while these decadal time scale synchronous changes with 20-110 periodicity years were 56-65\% of the total locust outbreak years of the past 1000 years. Historical records on ``drought locust'' were true, as we found that the drought of spring-summer season in the northern region caused the highest regional locust outbreaks, but it is not a sensitive factor for locust outbreaks in the wet-humid Yangtze River region. Although warm winter condition is a key factor for locust egg survival and preservation, it works well when winter temperatures reach to -10 degrees to -30 degrees C in the northern region but is not a limiting factor for locust survival in the warm southern region. We found that both interannual and decadal variability of higher temperature changes have led to the highest locust outbreaks in the past 1000 years, so as to suggest that greenhouse-effected climate warming would increase the severe locust outbreaks in the area.

Zi006 Zimmer, C., 1999. Life after chaos. Science, 284(5411): 83-86.    Zi006.pdf   

Abstract: After years of hunting for chaos in the wild, ecologists have comp up mostly empty-handed. But the same equations failed to find chaos are turning up stunning insights into how environmental forces and internal dynamics make populations rise and fall

Zi031 Zimov, S. and Chuprynin, V. and Oreshko, A. and Chapin, F. and Reynolds, J. and Chapin, M., 1995. Steppe-tundra transition - a herbivore-driven biome shift at the end of the pleistocene. Am. Nat., 146(5): 765-794.    Zi031.pdf      

Abstract: A simulation model, recent experiments, and the literature provide consistent evidence that megafauna extinctions caused by human hunting could have played as great a role as climate in shifting from a vegetation mosaic with abundant grass-dominated steppe to a mosaic dominated by moss tundra in Beringia at the end of the Pleistocene. General circulation models suggest that the Pleistocene environment of Beringia was colder than at the present with broadly similar wind patterns and precipitation but wetter soils. These and other observations suggest that the steppelike vegetation and dry soils of Beringia in the late Pleistocene were not a direct consequence of an arid macroclimate. Trampling and grazing by mammalian grazers in tundra cause a shift in dominance from mosses to grasses. Grasses reduce soil moisture more effectively than mosses through high rates of evapotranspiration. Results of a simulation model based on plant competition for water and light and plant sensitivity to grazers and nutrient supply predict that either of two vegetation types, grass-dominated steppe or moss-dominated tundra, could exist in Beringia under both current and Pleistocene climates. The model suggests that moss-dominated tundra is favored when grazing is reduced below levels that are in equilibrium with climate and vegetation. Together these results indicate that mammalian grazers have a sufficiently large effect on vegetation and soil moisture that their extinction could have contributed substantially to the shift from predominance of steppe to tundra at the Pleistocene-Holocene boundary. Our hypothesis suggests a mechanism by which the steppe ecosystem could be restored to portions of its former range. We also suggest that mammalian impacts on vegetation are sufficiently large that future vegetation cannot be predicted from climate scenarios without considering the role of mammals.


ETH Zurich, Systems Ecology -- Created: Thu May 17 19:21:44 CEST 2012 by afischli from BibDesk data base 'Some Refs.bib'
Andreas Fischlin, mailto:andreas.fischlin@env.ethz.ch