DISSERTATION RESEARCH: The role of natural enemies and resource availability in biological invasions by plants

人类引入新地区的一些植物物种能够传播并胜过本地植物的一个可能原因是，引入的植物相对没有天敌，如食草动物和病原体。然而，从敌人手中释放引进物种的好处可能取决于新栖息地的资源水平，如土壤养分。在更肥沃的栖息地，许多植物生长得更快，降低了它们对敌人的化学或物理防御。这将增加没有敌人的优势，从而增加引进植物胜过本地植物的能力。本项目将通过在不同土壤肥力水平下种植6种引进种和14种本地种，并在有无本地昆虫、食草动物和真菌病原体保护的情况下进行一系列实验，来验证这种生物入侵的资源-敌人释放假说。了解使一些引进物种在其新范围内占据主导地位的因素对自然资源管理至关重要。入侵物种导致生物多样性下降，每年给美国经济造成近1200亿美元的损失。这个项目的结果将帮助管理者将目标控制在最危险的栖息地和物种上。该项目还将为几名本科生提供实地和实验室环境下的实践研究经验，并将研究结果传播给高中生物课和当地社区。

One likely reason that some of the plant species introduced by humans to new regions are able to spread and outcompete native plants is that the introduced plants are relatively free from natural enemies such as herbivores and pathogens. However, the benefits to an introduced species of release from enemies may depend on the levels of resources such as soil nutrients in the new habitat. In more fertile habitats, many plants grow more rapidly and lower their chemical or physical defenses against enemies. This should increase the advantage of the absence of enemies and thus the ability of introduced plants to outcompete native ones. This project will test this resource-enemy release hypothesis of biological invasion through a series of experiments in which 6 introduced species and 14 native species are grown at different levels of soil fertility and with and without protection from native insect herbivores and fungal pathogens. Understanding the factors that allow some introduced species to become dominant in their new ranges is critical for natural resource management. Invasive species cause declines in biodiversity and cost the U.S. economy nearly $120 billion annually. Results from this project will help managers target control to the habitats and species most at risk. The project will also provide hands-on research experience in field and laboratory settings to several undergraduate students, and disseminate findings to high school biology classes and the local community.