Perturbation and Recovery of an Old-field Food Web

生态学的一个核心目标是发展一套健全的科学原则，帮助解释自然或人为干扰对生物多样性和自然生态系统功能的影响。 这一奋进的动机是希望：（1）预测生态系统的命运，以及其中所包含的生物多样性，特别是当本地物种消失或外来物种入侵时，由于干扰，以及（2）通过合理的管理恢复这些系统的自然功能。拟议的研究旨在通过研究新英格兰草地生态系统中的顶级捕食者物种如何控制这些草地内的植物物种多样性以及干扰如何改变这种控制来帮助制定进行合理环境管理所需的科学原则。 过去对这一系统的研究表明，在夏季，蜘蛛等顶级捕食者很重要，因为它们控制着蝗虫和甲虫等咀嚼树叶的食草动物对植物物种造成的损害。 目前还不清楚环境干扰如何改变顶级捕食者控制草食动物损害的能力。 拟议的研究将对生态系统造成干扰，通过实验将蜘蛛捕食者从2米x2米的野外地块中排除1至4年。 随后，我们将监测如何植物损害的草食动物和植物物种组成的领域地块的变化作为短期和长期的捕食者排斥的结果。 作为这项实验的一部分，我们还将在蜘蛛捕食者被排除1至3年后重新引入到地块中。 其目的是确定系统是否可以恢复到原来的植物物种组成和功能后，固定的干扰期。 目前，生态学家认为，改变自然生态系统中顶级捕食者的存在应该对生态系统功能产生持久的影响。 然而，很少有研究评估生态系统的长期反应时，顶级捕食者被删除，后来重新引入。 拟议的工作将提供关键的洞察力，以了解扰乱生态系统的自然完整性对生态系统功能的长期影响。

A central goal in ecology is to develop a set of sound scientific principles that help to explain the effects of natural or human-induced disturbances on biodiversity and the functioning of natural ecosystems. This endeavor is motivated from a desire to: (1) forecast the fate of ecosystems, and the biodiversity contained within them, especially when native species are lost or exotic species invade as a consequence of the disturbances, and (2) restore the natural function of those systems through sound management. The proposed research aims to help develop the scientific principles needed to conduct sound environmental management by studying how top-predator species in New England meadow ecosystems control the diversity of plant species within those meadows and how disturbances alter that control. Past research on this system has revealed that, within a summer season, top predators such as spiders are important because they control the amount of damage that leaf-chewing herbivores such as grasshoppers and beetles inflict on plant species. It is unknown how environmental disturbances alter the ability of top-predators to control the herbivore damage. The proposed research will cause disturbances to the ecosystem by experimentally excluding spider predators from 2 m x 2m field plots for periods of 1 to 4 years. Subsequently, we will monitor how plant damage by herbivores and plant species composition of the field plots change as a consequence of short- and long-term predator exclusion. As part of this experiment, we will also reintroduce spider predators to plots after they have been excluded for 1 to 3 years. The aim is to determine whether the system can be restored to its original plant species composition and functioning following fixed periods of disturbance. Currently, ecologists believe that altering the presence of top predators in natural ecosystems should have lasting consequences for ecosystem function. Few studies, however, have evaluated the long-term responses of ecosystems when top-predators are removed and later reintroduced. The proposed work will offer key insight into the long-term consequences of disturbing the natural integrity of ecosystems on ecosystem function.