BOREAL FOREST RESPONSES TO CLIMATE-CHANGE SCENARIOS ALONG AN ECOCLIMATIC TRANSECT IN CENTRAL CANADA

The FORSKA2 patch model was used to simulate responses of forest bioma ss and species composition to four GCM projections of climate change a t 11 locations along a transect oriented northeast-southwest across th e boreal zone of central Canada. In agreement with earlier results, FO RSKA2 produced estimates of present-day biomass accumulation and funct ional types very consistent with local inventory data. Simulated respo nses to the four GCM scenarios of climate change produced different re sults. The GFDL scenario consistently reduced total biomass accumulati on compared to present-day conditions, whereas the other three GCMs pr oduced overall increases. In the north, where ecosystem productivity i s thought to be limited by low temperature, changes in steady-state bi omass accumulation and species composition were relatively minor. In t he south, where productivity is probably limited by summer water defic its, the GCM scenarios resulted in larger absolute changes, with gener ally large increases under GISS, and OSU and generally smaller increas es under UKMO. Pronounced changes in species composition were not evid ent in most simulations, with the exception that warmer winter tempera tures evidently allowed invasion by species currently excluded through intolerance to winter minima.