Collaborative Research: Rates of Long-Term Climate and Vegetation Change in Eastern North America and Europe

对北美东部化石花粉数据变化率的分析表明，许多地点在1万至1.4万年前的最后一次冰川消融期间经历了重大变化，并在过去的1000年里再次经历了重大变化。该研究的主要目的是确定北美东部过去3000年和瑞典过去14000年气候和植被变化的时间、幅度和地理模式。来自北美东部一系列地点的高频花粉数据将用于详细分析过去一千年中发生的明显快速变化，并整理气候和哥伦比亚之后的人为原因。来自瑞典南部40个晚冰期遗址的数据将用于比较斯堪的纳维亚晚冰期与北美晚冰期的时间结构。由于农业和其他人类活动（而不是气候影响）造成的植被变化率将通过对比人类影响强烈的地区与受影响较小的边缘地区的地点来评估。这项研究将确定北美东部和欧洲植被快速变化的同步程度，从而确定大气环流重大快速变化的可能时间。研究结果还将揭示在多大程度上最近的植被是暂时的，以及在多大程度上北美的预定居植被有理由作为现代研究的稳态基线。

Analyses of rates of change in fossil-pollen data from eastern North America reveal that many sites experienced major changes 10,000-14,000 years ago during the last deglaciation and again during the last 1000 years. The major objective of the proposed research is to determine the timing, magnitude, and geographic patterns of the changes in climate and vegetation during the past 3000 years in eastern North America and during the past 14,000 years in Sweden. High-frequency pollen data from an array of sites across eastern North America will be used to analyze in detail the apparently rapid changes occurring during the past millennium and to sort out the climatic and post- Columbian anthropogenic causes. Data from 40 late-glacial sites in southern Sweden will be used to compare the temporal structure of the Scandinavian late-glacial with that of North America. Rates of vegetation change attributable to agriculture and other human activities (as opposed to climatic influences) will be evaluated by contrasting Swedish sites from areas having intensive human impact iwth those from marginal areas receiving little impact. This research will establish the degree to which rapid vegetation changes in eastern North America and Europe are synchronous and will thus identify probable times of major rapid changes in atmospheric circulation. The results will also reveal the degree to which recent vegetation is transitory and to which presettlement vegetation in North America justifiably serves as a steady-state baseline for modern studies.