Predator Identity and Trophic Control of Biodiversity and Ecosystem Function

长期以来，捕食者一直因其在控制昆虫物种爆发方面的作用而受到重视，这些昆虫物种可以对其特定的宿主植物物种造成相当大的损害。 生态科学现在提出的理论是，通过保护植物免受损害，捕食者可能在生态系统中发挥比以前认为的更重要的作用。 不同的捕食者喜欢不同种类的昆虫猎物。 这种偏好可能会引导植物物种（生物多样性）的组合在生态系统中生存。 反过来，植物生物多样性的水平可以影响重要的生态系统服务的水平，如有机物质的分解和氮等重要营养物质的循环，然后反馈影响活植物组织的生产率。 本研究将在草地生态系统中对不同的蜘蛛捕食者物种和蝗虫进行实验。 它将检验这样一个假设，即每一种捕食者物种将对蝗虫产生独特的影响，而蝗虫反过来又对植物物种的组成和生态系统服务的水平产生独特的影响。 此外，它还将衡量单个捕食者物种对生态系统的影响。 这项研究将在试验田中单独或结合不同的捕食者物种，并测量蝗虫的丰度、自然植物物种的丰度以及有机物（植物落叶）分解、氮循环和植物生产的速度。 这项研究将有助于提高生物控制措施的精确性，确定哪些捕食者物种的组合最好地实现草地生态系统中植物物种多样性和植物产量的理想水平。

Predators have long been valued for their role in controlling outbreaks of insect species that can inflict considerable damage to their specific host plant species. Ecological science is now theorizing that by protecting plants from damage, predators may play an even more critical role in ecosystems than previously thought. Different predator species prefer different kinds of insect prey. Such preference may steer which combinations of plant species (biodiversity) survive in an ecosystem. The level of plant biodiversity, in turn, can impact the level of important ecosystem services like the breakdown of organic matter and cycling of important nutrients such as nitrogen, which then feeds back to influence the production rate of living plant tissue. This study will experiment with different spider predator species and grasshoppers in a grassland ecosystem. It will test the hypothesis that each predator species will uniquely affect grasshoppers which, in turn, uniquely affects the composition of plant species and the level of ecosystem services. In addition, it will measure how individual predator species effects on the ecosystem add up. The study will hold different predator species, individually and in combination, in experimental field plots and measure the abundance of grasshoppers, the abundance of naturally occurring plant species, and the rates of organic matter (plant leaf litter) decomposition, nitrogen cycling and plant production. The study will help to increase the precision of biological control measures by identifying which combinations of predator species best achieve desired levels of plant species diversity and plant production in grassland ecosystems.