SGER: The Effect of Preexisting Differences in Invasive Plant Abundance on he Impacts of Hurricane Rita on East Texas bottomland hardwood forests

干扰被广泛认为促进了入侵（“干扰假说”），可能是由于相对于本地植被的吸收，暂时增加了资源的供应。然而，这一理论的主要内容尚未得到验证。此外，越来越多的证据表明，定殖在决定当地多样性和物种组成方面起着重要作用（“补充限制假说”），但尚未在森林中进行实验测试。总之，这两种假设表明，干扰产生的“机会之窗”、在干扰中幸存下来的植被特征以及利用暂时丰富资源的种子或幼苗的可用性之间存在着重要的相互作用。2005年9月，飓风丽塔的风眼经过德克萨斯州东部，给大灌木丛国家保护区的一项长期实验造成了广泛的破坏。实验包括16块40英亩的地块，其中一半的地块已经移除了成熟的入侵中国牛油树。由于这些清除，这些地块在不同生命阶段的牛脂树密度不同。这是一个机会来检查一个大的干扰对不同的预先存在的主要入侵植物物种密度的样地由于随机实验设计的影响。项目将于2005年秋季和2006年春季在这些受干扰地点内设立采样区并进行监测。将分析高分辨率图像以确定更大尺度上的扰动。更广泛的影响：这项工作将为一个快速变化的领域带来新的知识，并增加社会重要性。它将使本科生为科学事业做好准备，培养研究生，并通过传播我们的数据和结果，直接在该领域促进与资源管理人员的合作。它将为未来入侵物种的预测提供实用信息，并有助于指导当前问题物种的管理。

Disturbance is widely believed to facilitate invasions ("Disturbance Hypothesis") perhaps by temporarily increasing the supply of resources relative to uptake by native vegetation. However, the main elements of this theory remain untested. In addition, there is growing evidence that colonization plays an important role in determining local diversity and species composition ("Recruitment Limitation Hypothesis") but no experimental tests have been performed in forests. Together, these two hypotheses suggest that an important interplay occurs among "windows of opportunity" created by disturbance, the characteristics of the vegetation that survive the disturbance, and the availability of seeds or seedlings to take advantage of temporarily abundant resources. In September 2005, the eye of Hurricane Rita passed through eastern Texas causing extensive damage to a long-term experiment in the Big Thicket National Preserve. The experiment consists of 16 forty acre plots in which the mature invasive Chinese Tallow Trees have been removed from half of the plots. Because of these removals, the plots differ in the density of Tallow Trees in multiple life stages. This is an opportunity to examine the effect of a large disturbance on plots that differ in the preexisting density of a dominant invasive plant species due to random experimental design. The PI will set up and monitor sampling areas within these disturbed sites in fall 2005 and in spring 2006. High resolution imagery will be analyzed to determine disturbance at larger scales. Broader Impacts: This work will bring new knowledge to a rapidly changing field of increasing societal importance. It will prepare undergraduate students for science careers, train graduate students, and facilitate collaborations with resource managers both directly in the field and through the dissemination of our data and results. It will provide practical information for the prediction of future invasive species and help guide the management of current problem species.