Understanding the Impacts of Climate Change On Northeastern North American Forest Ecosystems.

Global climate change has emerged as one of the most important environmental and policy issues of the 21^st century.  As such, there is an urgent need to continue to build a sound scientific basis for national and international policies regulating carbon sequestration and greenhouse gas emissions.  Towards this end, NE Forests 2100 was established in 2005.  NE Forests 2100 is a coalition of U.S. and Canadian environmental scientists whose goal is to synthesize current scientific information on the impacts of historic and projected regional climate change on forested ecosystem of the northeastern U.S. and eastern Canada, and to make this information available to policymakers, land managers, and the concerned public.

Results from this synthesis will be presented.  These results show unequivocally that both temperature and precipitation have increased across the region over the last century, with associated changes in snow and hydrologic regimes.  Model predictions indicate that temperature and precipitation will continue to increase over the next century.  Changes in the timing of precipitation, coupled with greater annual evapotranspiration associated with earlier spring and later autumn, will paradoxically contribute to increased frequency and intensity of droughts.  These changes, particularly in association with other anthropogenic influences (e.g., increases in atmospheric CO₂, acid deposition, and tropospheric ozone concentrations) will have profound direct and indirect effects on forest productivity and tree species composition, “nuisance species” (including pests, pathogens, and invasive species), wildlife, and forest nutrient cycling.  Complex life histories and a cascade of feedbacks between ecosystem components may even overwhelm, direct climatic effects, creating lags and thresholds in response, and potentially lead to sudden large shifts in forest ecosystem health, productivity and the goods and services that these forests offer.