Climate Change Impacts for the Conterminous USA: An Integrated Assessment Part 6 Distribution and Productivity of Unmanaged Ecosystems
In this study, we characterize the range in response of unmanaged ecosystems to 12 climate change scenarios. We obtained this response by simulating the climatically induced shifts in net primary productivity and geographical distribution of major biomes of the conterminous U.S. with the BIOME3 model. Under current or baseline climate, BIOME3 captured well the potential distribution of major biomes across the U.S. BIOME3 also reproduced the general trends of observed NPP acceptably. The NPP predictions were accurate for forests but not for grasslands where the simulated values were always greater than those observed. In general, the inclusion of a CO2-fertilization effect as a modeling factor either favored an increase or alleviated the loss in NPP brought about by the climate change scenarios. Changes in NPP were associated with changes in the geographic distribution of major biomes. The methods and models employed here were useful to identify (a) the range in response of unmanaged ecosystem in the U.S. to climate change and (b) the areas of the country where, for a particulate scenario of climate change, land cover changes would be most likely.