Among the most dramatic effects of global climate change of the next two centuries may be the increased frequency and/or intensity of fires in temperate forests. Natural fire regimes are largely unknown, making it difficult to speculate on the response of fire regimes to rapid climate change. The influence of fire on forest composition and structure might have important feedback effects on climate through its effects on the cycling of greenhouse gases. The last 1000 years provides an example of rapid climate change in eastern North America that can serve as a basis for understanding the role of fire when climate changes. Forest transitions may have occurred as a consequence of changes in the fire regime or changes in the climate. The null hypothesis that the fire regime has not changed across the ecotone of deciduous and mixed conifer forest in eastern North America during the last 2500 years will be tested. A new method of obtaining long-term fire histories will be used in this research. Individual fires in the stratigraphic record will be determined using petrographic thin sections of annually laminated (varved) lake sediments to produce long-term fire frequencies. The method will be applied to a network of small lakes with varved sediments across our study area. The individual sites will provide a means for assessing the role of fire for influencing forest changes in different climatic and vegetation settings. The combined data set will establish the broad spatial and temporal patterns of fire regimes and forest composition that attend climate change at a subcontinental scale. Results will facilitate evaluation of future climate change on natural ecosystems.
