Long-term Processes Affecting the Hemlock-hardwoods Mosaic at Sylvania, Michigan

密歇根州北部Sylvania荒野地区铁杉-阔叶林马赛克的长期森林动态将利用小森林空洞中的化石花粉进行研究。记录在沉积物中的个体林木的历史，将确定3000年前铁杉入侵之前以火灾为主的森林生态系统中的演替群落，从而有可能了解干扰是否使一些地区特别容易入侵，从而影响了铁杉的进入和自那以后占据这些地点的铁杉补丁的位置。通过测定铁杉到达极端环境中的一系列地点、沼泽或湖泊附近或粗糙土壤上的时间，我们将检验另一种假设，即物理环境的差异是导致铁杉斑块位置的原因。对沉积物的精细分析和对结果数据的时间序列分析将探索3000年前扰动制度从火转变为风时演替路径的变化。建模将被用来调查森林镶嵌中林分之间边界位置发生的动态变化。这些结果将有助于展示森林群落对气候的反应，包括可能伴随全球变暖而来的干扰制度的变化。了解景观上森林群落镶嵌格局的起源可能有助于森林管理者保护古老森林林分的这一方面的生物多样性。

Long-term forest dynamics in the hemlock-hardwood forest mosaic of the USFS Sylvania Wilderness Area, northern Michigan, will be studies using fossil pollen in small forest hollows. Histories of individual forest stands, recorded in the sediment, will identify successional communities in the fire-dominated forest ecosystem before hemlock invasion 3000 years ago, making it possible to see whether disturbances made some areas particularly invasible, thus influencing hemlock entry and the locations of hemlock patches that have occupied those sites ever since. By dating hemlock arrival at a series of sites in extreme environments, near bogs or lakes or on coarse soils, we will test the alternative hypothesis that differences in the physical environment were responsible for the locations of hemlock patches. Fine-scale analyses of sediment and time-series analyses of the resulting data will explore changes in successional pathways as the disturbance regime changed from fire to wind 3000 years ago. Modeling will be used to investigate the dynamic changes that have occurred in the positions of boundaries between stands in the forest mosaic. The results will be useful for demonstrating the response of forest communities to climate, including changes in disturbance regimes which may accompany Global Warming. Understanding the origin of the mosaic pattern of forest communities on the landscape may help forest mangers to preserve this aspect of the biodiversity of old-growth forest stands.