WILDLIFE AND CLIMATE-CHANGE - ASSESSING THE SENSITIVITY OF SELECTED SPECIES TO SIMULATED DOUBLING OF ATMOSPHERIC CO2

We explored, using computer simulations, the sensitivity of four mamma l species (elk, Cervus canadensis; white-tailed deer, Odocoileus virgi nianus; Columbian ground squirrel, Spermophilus columbianus; and chipm unk, Tamias striatus) within the continental USA to the effect of anti cipated levels of global climate change brought about by a doubling of atmospheric CO2. Sensitivity to the direct effects of climate change were evaluated using a climate-space approach to delineate the range o f thermal conditions tolerable by each species. Sensitivity to indirec t effects were evaluated by quantifying the association of each specie s to the current vegetation distribution within the continental USA an d using this association to assess whether wildlife species distributi ons might shift in response to vegetation shifts under climate change. Results indicate that altered thermal conditions alone should have li ttle or no effect on the wildlife species' distributions as physiologi cal tolerance to heat load would allow them to survive. Analyses of th e effects of vegetation change indicate that deer and chipmunks should retain their current distributions and possibly expand westward in th e USA. For Elk and ground squirrels, there is a possibility that their current distributions would shrink and there is little possibility th at each species would spread to new regions. This work emphasizes that the distributions of the four mammalian species are likely to be infl uenced more by vegetation changes than by thermal conditions. Future e fforts to understand the effects of global change on wildlife species should focus on animal-habitat and climate-vegetation linkages.