Dissertation Research: The nature of and mechanisms responsible for northern hardwood forest Lepidoptera community dynamics

长期监测表明，美国东北部阔叶林中毛虫的数量每年都会出现剧烈波动。值得注意的是，这种波动涉及数十到数百种鳞翅目昆虫，对鸟类的数量影响很大。以前的研究已经确定了气候与鳞翅目丰度波动之间的相关性，但将气候与毛虫丰度联系起来的具体机制尚未阐明。该项目利用四年来对鳞翅目昆虫丰度的系统采样来探讨两个重要问题。首先，这些昆虫的动态是不是种群数量同步变化的独立物种集合的结果？其次，这些物种有哪些共同特征可以产生这种同步性？该项目还测试了导致这些同步波动的潜在机制：气候变化影响森林营养循环，从而影响这些昆虫的取食成功和种群动态。这项研究的结果将显示气候变化的特定方面如何影响本地昆虫的种群增长率，这些本地昆虫是该生态系统中的主要草食动物，是新热带候鸟的主要食物来源，有时还是落叶害虫。这些结果将为保护生物学、森林管理和科学政策提供信息。这项工作已经提高了人们对鳞翅目昆虫生物学和自然历史的了解，鳞翅目昆虫是美国东北部本土生物多样性的主要组成部分。这项研究的一个成果是建立了一个在线、开放访问的数据库，其中包含了在这些森林中可以找到的数百种鳞翅目昆虫的信息。这将成为研究人员、教育工作者、政策制定者和自然爱好者的资源。来自多个学校的本科生将继续参与该项目，为学生提供培训生态研究方法和原理的机会。

Long-term monitoring shows that the abundance of caterpillars tends to fluctuate dramatically from year to year in hardwood forests of the northeastern U.S. Notably, these fluctuations involve dozens to hundreds of Lepidoptera species and have strong impacts on bird populations. Previous research has identified correlations between climate and the fluctuations in Lepidoptera abundance, but the specific mechanisms that link climate to caterpillar abundance have not been elucidated. This project uses four years of systematic sampling of Lepidoptera abundance to pursue two important questions. First, are the dynamics of these insects a result of collections of separate species whose populations vary synchronously? Second, what characteristics are shared by these species that could produce this synchrony? The project also tests a potential mechanism causing these synchronous fluctuations: climate variability affects forest nutrient cycles, thereby influencing the feeding success and population dynamics of these insects. Results from this research will show how specific aspects of climate change influence population growth rates of native insects that are the chief herbivores in this ecosystem, are the primary food source of Neotropical migrant birds, and are sometimes defoliating pests. These results will inform conservation biology, forest management, and science policy. The work has already improved understanding of the biology and natural history of Lepidoptera, the major component of native biodiversity in the northeastern U.S. A product of the research is an online, open-access, database of information about the hundreds of Lepidoptera species that can be found in these forests. This will serve as a resource for researchers, educators, policy makers, and nature enthusiasts. Undergraduates from a number of schools will continue to be involved in the project, providing opportunities to train students in ecological research methods and principles.