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Accueil du site → Doctorat → États-Unis → 2000 → Potential vegetation response to future climate change in western North America and its implications for biological conservation and geographical conceptualizations of place

University of Oregon (2000)

Potential vegetation response to future climate change in western North America and its implications for biological conservation and geographical conceptualizations of place

Shafer, Sarah

Titre : Potential vegetation response to future climate change in western North America and its implications for biological conservation and geographical conceptualizations of place

Auteur : Shafer, Sarah

Université de soutenance : University of Oregon

Grade : Doctor of Philosophy (2000)

Résumé
This dissertation examines the potential response of vegetation to climate change using two different simulation methods. First, response surfaces are used to describe the relationship between bioclimatic variables and the distribution of individual tree and shrub taxa in western North America at a 25-km resolution. Second, an equilibrium terrestrial biogeography model (BIOME4, Kaplan & Prentice in prep.), modified for regional application, is used to simulate biome distributions in the Pacific Northwest at a 2.5-minute resolution. Taxon and biome distributions are simulated under present climate, using observed climate data (1951–1980, 30-yr mean). The response surface approach is validated using observed species range data, while the biome model is validated using AVHRR-derived land cover data. Future species distributions are simulated using general circulation model (GCM) scenario data for 2090–2099 (10-yr mean) generated by the HADCM2, CGCM1 and CSIRO GCMs. Future biome distributions are simulated using scenario data for 2050–2059 (10-yr mean) from the HADCM2 GCM. All of the future climate scenarios assume a 1% per year compound increase in greenhouse gases and changes in SO4 aerosol concentrations based on the Intergovernmental Panel on Climate Change IS92a scenario. Ecoregions defined by The Nature Conservancy for conservation planning are used to evaluate the simulated changes in biome distributions. The simulated biome distributions are also evaluated for their potential implications for places in the Pacific Northwest. The results of these analyses indicate that the simulated response of vegetation to climate change is large ; species and biome distributions shift in all directions and over large distances, with significant contraction and fragmentation of distributions. Changes of this magnitude would have significant impacts on the success of conservation efforts in western North America. Notably, the shifts in species distributions simulated by the three different GCM scenarios display substantial agreement in the magnitude and direction of change. The effects of climate change will also be expressed through the physical, social, and cultural dimensions of places. The analyses indicate that including physical processes in geographical conceptualizations of place is critical for a better understanding of the potential impacts of future climate change. This dissertation includes my co-authored materials.

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