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

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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.