RUI: Dynamics of European Buckthorn (Rhamnus cathartica L.) Invasion in the Northeastern United States

外来入侵植物威胁着世界各地自然区域的生态完整性和经济价值。尽管这个日益严重的问题很严重，但我们对外来植物如何在新地区扎根并在景观中移动的理解还很薄弱。本研究的目的是描述原产于欧亚大陆的灌木欧洲鼠李（Rhamnus cathartica）在北美新地区的殖民过程，以及该过程如何随生态环境而变化。野外观察和实验将用于检查次生林落叶林、针叶林和废弃农田的殖民化过程的每个阶段。小气候、土壤和驻地动物的差异将被认为是定殖变异的潜在来源。环境的空间结构也将被视为影响殖民化的一个因素。详细的林分水平图与物种组成、树冠间隙、边缘和溪流的分布有关，将揭示促进欧洲沙棘殖民和传播的因素。航空摄影和地理信息系统将能够测量该植物所占地区的大小、形状和空间背景。这项研究将证明北美森林的破碎化是否有助于促进或抑制欧洲沙棘的传播。欧洲鼠李与本土植物竞争，是燕麦冠锈菌的宿主，这是一种攻击燕麦作物的疾病。在这种灌木中筑巢的本地鸟类被捕食的几率很高，欧洲鼠李的叶子可能对本地哺乳动物有毒。这项研究将使人们对这种相对未被研究的物种的生理学和生态学有更深入的了解。此外，本研究将有助于了解入侵成功如何受到入侵生态系统特性的影响。这项研究还将量化由于木材采伐和农业用地废弃而导致的森林破碎化如何影响外来物种在景观中的移动。尽管许多入侵物种是在人类改造的环境中发现的，但在原始自然区域中入侵物种的存在越来越受到关注。了解环境背景的影响，在特定的环境中以及在景观的环境之间，将指导土地管理者和科学家识别对自然环境的潜在威胁。

Invasive non-native plants threaten the ecological integrity and economic value of natural areas throughout the world. Despite the severity of this growing problem, our understanding of how exotic plants become established in new areas and move across the landscape is weak. The objective of this research is to describe the process by which European buckthorn (Rhamnus cathartica), a shrub native to Eurasia, colonizes new areas in North America and how that process varies with ecological context. Field observations and experiments will be used to examine each stage of the colonization process in second-growth deciduous forests, conifer plantations, and abandoned agricultural fields. Differences in microclimate, soils, and resident fauna will be considered as potential sources of variation in colonization. Spatial configuration of the environment also will be considered as a factor affecting colonization. Detailed stand-level maps relating species composition, canopy gaps, edges, and streams to European buckthorn distribution will reveal factors facilitating colonization and spread. Aerial photographs and geographic information systems will allow measurement of size, shape and spatial context of areas occupied by this plant. This research will demonstrate whether fragmentation of North American forests serves to promote or inhibit the spread of European buckthorn.European buckthorn competes with native plants and is a host of oat crown rust fungus, a disease that attacks oat crops. Native birds nesting in this shrub experience high rates of predation, and leaves of European buckthorn may be toxic to native mammals. This research will lead to a greater knowledge of the physiology and ecology of this relatively unstudied species of conservation concern. In addition, this research will contribute to understanding of how invasion success is affected by the properties of invaded ecosystems. This study also will quantify how forest fragmentation due to timber harvest and abandonment of agricultural lands affects the movement of an exotic species across the landscape. Although many invasive species are found in human-modified environments, there is growing concern about the presence of invasive species within pristine natural areas. Understanding the effect of environmental context, within particular settings and among settings in the landscape, will guide land managers and scientists to identify potential threats to natural environments.