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之所以能够传播并胜过本地植物，一个可能的原因是，引进的植物相对不受食草动物和病原体等天敌的影响。然而，引入物种从敌人那里释放的好处可能取决于新栖息地的土壤养分等资源水平。在更肥沃的生境中，许多植物生长得更快，对敌人的化学或物理防御能力较低。这应该会增加没有敌人的优势，从而提高引进植物胜过本土植物的能力。该项目将通过一系列实验来验证生物入侵的资源-天敌释放假说。在这些实验中，6个引进物种和14个本地物种在不同的土壤肥力水平上种植，并对本地昆虫、食草动物和真菌病原体进行保护和不保护。了解允许一些引进物种在其新的范围内成为优势物种的因素对于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。该项目的结果将帮助管理者有针对性地控制最危险的栖息地和物种。该项目还将向几名本科生提供实地和实验室环境中的实践研究经验，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.