Collaborative Research: Long-Term Fire Regimes in Eastern North America

未来两个世纪全球气候变化最显著的影响之一可能是温带森林火灾的频率和/或强度增加。自然火灾制度在很大程度上是未知的，因此很难推测火灾制度对快速气候变化的反应。火对森林组成和结构的影响可能通过对温室气体循环的影响而对气候产生重要的反馈作用。过去1000年提供了北美东部快速气候变化的一个例子，可以作为理解气候变化时火的作用的基础。森林过渡可能是由于火灾制度的变化或气候的变化而发生的。过去2500年来，北美东部落叶针叶林和混交林交错带的火灾制度没有改变的零假设将得到检验。这项研究将使用一种新的方法来获取长期火灾历史。地层记录中的个别火灾将使用每年层状(变色)湖泊沉积物的岩石学薄片来确定，以产生长期火灾频率。该方法将应用于我们研究区域内具有不同沉积物的小湖泊网络。这些个别地点将提供一种手段，用于评估火灾在不同气候和植被环境中影响森林变化的作用。合并后的数据集将建立次大陆尺度上应对气候变化的火灾制度和森林构成的广泛时空模式。结果将有助于评估未来气候变化对自然生态系统的影响。

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.