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Pond, Greg
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Pooler Smith 2005.pdf
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SIM-SPA
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Population Dynamical Consequences of Climate Change for a Small Temperate Songbird
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Predicting the effects of an expected climatic change requires estimates and modeling of stochastic factors as well as density-dependent effects in the population dynamics. In a population of a small songbird, the dipper (Cinclus cinclus), environmental stochasticity and density dependence both influenced the population growth rate. About half of the environmental variance was explained by variation in mean winter temperature. Including these results in a stochastic model shows that an expected change in climate will strongly affect the dynamics of the population, leading to a nonlinear increase in the carrying capacity and in the expected mean population size.
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Populations of migratory bird species that did not show a phenological response to climate change are declining
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Recent rapid climatic changes are associated with dramatic changes in phenology of plants and animals, with optimal timing of reproduction advancing considerably in the northern hemisphere. Some species may not have advanced their timing of breeding suffi- ciently to continue reproducing optimally relative to the occur- rence of peak food availability, thus becoming mismatched com- pared with their food sources. The degree of mismatch may differ among species, and species with greater mismatch may be char- acterized by declining populations. Here we relate changes in spring migration timing by 100 European bird species since 1960, considered as an index of the phenological response of bird species to recent climate change, to their population trends. Species that declined in the period 1990–2000 did not advance their spring migration, whereas those with stable or increasing populations advanced their migration considerably. On the other hand, popu- lation trends during 1970–1990 were predicted by breeding hab- itat type, northernmost breeding latitude, and winter range (with species of agricultural habitat, breeding at northern latitudes, and wintering in Africa showing an unfavorable conservation status), but not by change in migration timing. The association between population trend in 1990 –2000 and change in migration phenology was not confounded by any of the previously identified predictors of population trends in birds, or by similarity in phenotype among taxa due to common descent. Our findings imply that ecological factors affecting population trends can change over time and suggest that ongoing climatic changes will increasingly threaten vulnerable migratory bird species, augmenting their extinction risk.
conservation extinction risk migration phenology population trends
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Porter 1994 Lake Waccamaw.pdf
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PEK-RIC
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Porter Horn 1980.pdf
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PEK-RIC
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Posey 2002.pdf
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Post 1982.pdf
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PEK-RIC
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Post-clearcut dynamics of carbon, water and energy exchanges in a midlatitude temperate, deciduous broadleaf forest environment
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Clearcutting and other forest disturbances perturb carbon, water, and energy balances in significant ways, with corre- sponding influences on Earth’s climate system through biogeochemical and biogeophysical effects. Observations are needed to quantify the precise changes in these balances as they vary across diverse disturbances of different types, severities, and in various climate and ecosystem type settings. This study combines eddy covariance and micrometeo- rological measurements of surface-atmosphere exchanges with vegetation inventories and chamber-based estimates of soil respiration to quantify how carbon, water, and energy fluxes changed during the first 3 years following forest clearing in a temperate forest environment of the northeastern US. We observed rapid recovery with sustained increases in gross ecosystem productivity (GEP) over the first three growing seasons post-clearing, coincident with large and relatively stable net emission of CO2 because of overwhelmingly large ecosystem respiration. The rise in GEP was attributed to vegetation changes not environmental conditions (e.g., weather), but attribution to the expan- sion of leaf area vs. changes in vegetation composition remains unclear. Soil respiration was estimated to contribute 44% of total ecosystem respiration during summer months and coarse woody debris accounted for another 18%. Evapotranspiration also recovered rapidly and continued to rise across years with a corresponding decrease in sensi- ble heat flux. Gross short-wave and long-wave radiative fluxes were stable across years except for strong wintertime dependence on snow covered conditions and corresponding variation in albedo. Overall, these findings underscore the highly dynamic nature of carbon and water exchanges and vegetation composition during the regrowth following a severe forest disturbance, and sheds light on both the magnitude of such changes and the underlying mechanisms with a unique example from a temperate, deciduous broadleaf forest.
Keywords: carbon balance, evapotranspiration, forest disturbance and regrowth, forest management, net ecosystem productivity
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Potential climate warming effects on ice covers of small lakes in the contiguous U.S.
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To simulate effects of projected climate change on ice covers of small lakes in the northern contiguous U.S., a process-based simulation model is applied. This winter icersnow cover model is associated with a deterministic, one-dimensional year-round water temperature model. The lake parameters required as model input are surface area, maximum depth, and Secchi depth as a measure of radiation attenuation. The model is driven by daily weather data. Weather records from 209 stations in the contiguous U.S. for the period 1961–1979 were used to represent past climate conditions. The projected climate changes due to a doubling of atmospheric CO2 were obtained from the output of the Canadian Climate Center Global Circulation Model. To illustrate the effect of projected climate change we present herein winter ice cover characteristics simulated, respectively, with inputs of past climate conditions Ž1961–1979., with inputs of a projected 2=CO2 climate scenario as well as differences of those values. The dependence of ice cover characteristics on latitude and lake characteristics has been quantified by making simulations for 27 lake types at 209 locations across the contiguous U.S. It was found that the 2=CO2 climate scenario is projected to delay ice formation on lakes by as much as 40 days and melt ice by up to 67 days earlier. Maximum ice thicknesses are projected to be reduced by up to 0.44 m ŽSault Ste. Marie, MI., and the ice cover periods will be shorter by up to 89 days ŽRock Springs, WY.. The largest changes are projected to occur east of Idaho from the Canadian border down to the states of Colorado, Nebraska, and Iowa and the northern parts of Illinois, Indiana, Ohio, and Pennsylvania. These changes would reduce fish winterkill in most shallow lakes of the northern states of the contiguous U.S. but may endanger snowmobiles and ice fishermen.
Keywords: climate change effect; ice cover; United States; lakes
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