Patterns of Species Loss in Forest Understory Plant Communities

9974041沃勒许多地区的植物群落正在以前所未有的速度失去物种。虽然造成这些损失的机制各不相同，而且往往难以确定，但似乎有一个总的趋势，即哪些物种最容易消失。稀有和本地物种通常面临更大的局部灭绝风险，物种丧失的模式往往导致大多数栖息地斑块包含常见和广泛的物种。栖息地的碎片化，在历史上的干扰制度的变化，外来物种的入侵，和食草动物的白尾鹿的人口增加似乎是近的机制，推动这些损失在各种栖息地。本研究将调查模式的社区组成和物种损失的林下植物群落在北方威斯康星州和密歇根州的上半岛的森林作为一种工具，以了解这些损失的性质，程度和机制。将从该地区分布在六个社区/土壤类型的120多个地点收集数据，以解决几个生态问题。为了测试物种损失的可预测性，将分析嵌套物种的组成。为了评估历史损失，当代物种存在数据将与John T.柯蒂斯和他的同事为这些森林。历史下降的模式将比较目前的模式之间的栖息地斑块嵌套，以评估如何以及目前的嵌套模式反映历史进程。分层空间采样将使我们能够构建物种面积曲线，用于群落和土壤类型之间的比较。这些结果将提高我们对自然群落动态、这些群落的历史变迁以及当前物种丧失机制的理解。

9974041WallerPlant communities in many areas are losing species at unprecedented rates. While the mechanisms responsible for these losses vary and are often difficult to identify, there appear to be general trends governing which species are most vulnerable to being lost. Rare and localized species are usually at greater risk of local extirpation, and patterns of species loss often result in most habitat patches containing common and widespread species. Habitat fragmentation, shifts in historic disturbance regimes, the invasion of exotic species, and herbivory by elevated populations of white-tailed deer all appear to be proximate mechanisms driving these losses in various habitats. This study will investigate patterns of community composition and species loss in understory plant communities in forests of northern Wisconsin and Michigan's upper peninsula as a vehicle to understand the nature, extent, and mechanisms of these losses. Data will be collected from 120+ sites distributed across six community/soil types in this region to address several ecological questions. To test the predictability of species loss, nested species compositions will be analyzed. To assess historic losses, contemporary species presence data will be compared to historical data collected by John T. Curtis and colleagues for these forests. Patterns of historical decline will be compared to current patterns of nestedness among habitat patches to assess how well current patterns of nestedness reflect historical processes. Hierarchical spatial sampling will allow us to construct species-area curves for comparisons across community and soil types. These results will improve our understanding of natural community dynamics, historical shifts in these communities, and current mechanisms of species loss.