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

森林草本植物群落中物种损失和生物均匀化的机制II.Waller，Donald M.威斯康星大学麦迪逊分校北方森林和威斯康星州南部大草原的历史数据显示，在过去的50年中，稀有物种和物种丰富度出现了系统性下降。 几种机制可能会导致这些损失，包括干扰制度的转变，外来杂草入侵，过度食草动物，酸沉降和气候变化的压力。 本项目将通过研究林下植物群落变化的详细模式来测试这些潜在的机制。 该项目利用了Curtis及其同事在20世纪50年代初编制的独特数据集，该数据集提供了数百个地点物种出现和丰度的准确基线数据。 威斯康星州南部的70多个森林遗址将被重新调查，以确定这些社区生态变化的性质、速度和原因。 这些结果将与柯蒂斯的历史数据进行比较，以绘制上层和下层组成的变化，外来物种的入侵，物种损失率和生物同质化。 总体而言，11种物种损失的替代机制（演替，灭火，外来物种入侵，气候变化，鹿放牧等）。会得到考验 详细的网站历史和地理信息系统分析的一些网站将允许当地干扰的历史和景观背景进行评估。 该项目利用一个独特的历史数据集，以确定导致植物群落变化的机制。 它将查明正在减少的物种，并大大扩大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、外来物种和关键食草动物（如鹿）的森林和野生动物管理者具有广泛的意义。 最后，该项目将支持针对自然资源管理人员、教育工作者和公众的外联工作，以确保这些成果得到广泛关注和适当回应。

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.