Mechanisms of Species Loss and Biotic Homogenization in Forest Herb Communities II.

森林草本群落物种流失与生物同质化机制[j]。沃勒，唐纳德·m威斯康星大学麦迪逊分校威斯康星北部森林和南部草原的历史数据显示，在过去的50年里，珍稀物种和物种丰富度有系统地下降。有几种机制可以解释这些损失，包括干扰制度的转变、外来杂草的入侵、过多的食草动物、酸沉积的压力和气候变化。这个项目将通过检查林下植物群落变化的详细模式来测试这些潜在的机制。这个项目利用了柯蒂斯和他的同事在20世纪50年代早期编制的一个独特的数据集，该数据集提供了数百个地点的物种发生和丰度的准确基线数据。威斯康辛州南部的70多个森林地点将被重新调查，以确定这些社区生态变化的性质、速率和原因。这些结果将与柯蒂斯的历史数据进行比较，以绘制层上和层下组成、外来物入侵、物种损失率和生物同质化的变化。总体而言，将测试11种物种丧失的替代机制（演替，火灾抑制，外来生物入侵，气候变化，鹿放牧等）。详细的遗址历史和对一些遗址的地理信息系统分析将有助于评估当地的干扰历史和景观背景。该项目利用独特的历史数据集来确定导致植物群落变化的机制。它将精确地指出物种的减少，并极大地扩展对整体群落组成如何响应当地和区域条件的理解。这些结果对负责管理森林、外来物种和鹿等重要食草动物的森林和野生动物管理者具有广泛的意义。最后，该项目将支持向自然资源管理人员、教育工作者和公众宣传的努力，以确保这些成果得到广泛关注和适当的反应。

Mechanisms of Species Loss and Biotic Homogenization in Forest Herb Communities II.Waller, Donald M.University of Wisconsin-MadisonHistorical data for northern forests and southern prairies of Wisconsin reveal systematic declines over the past 50 years in rare species and species richness. Several mechanisms might account for these losses including shifts in disturbance regimes, invading weedy exotics, overabundant herbivores, stress from acid deposition and climate change. This project will test these potential mechanisms by examining detailed patterns of change in understory plant communities. This project exploits a unique data set compiled by Curtis and colleagues in the early 1950's that provides accurate baseline data on species occurrences and abundances across hundreds of sites. More than 70 forest sites in southern Wisconsin will be resurveyed to determine the nature, rates, and causes of ecological change in these communities. These results will be compared to the historical Curtis data to chart changes in over-story and under-story composition, invasions by exotics, and rates of species loss and biotic homogenization. Overall, 11 alternative mechanisms of species loss (succession, fire suppression, invasion by exotics, climate change, grazing by deer, etc.) will be tested. Detailed site histories and GIS analyses of some sites will allow an assessment of local disturbance history and landscape context. This project exploits a unique historical data set to identify the mechanisms causing plant community changes. It will pinpoint declining species and greatly expand understanding of how overall community composition responds to local and regional conditions. Such results are of broad significance to forest and wildlife managers charged with managing forests, exotics, and keystone herbivores like deer. Finally, the project would support outreach efforts to natural resource managers, educators, and the public to ensure that these results gain broad attention and appropriate responses.