Trophic Cascades and Interacting Control Processes in a Detritus-based Terrestrial Food Web

WiseDEB 9815842陆地生态系统通常包含物种丰富的通才捕食者组合。 这些捕食者不仅捕食较低的营养水平，但也对其他物种的通才捕食者，相互作用被称为行会内捕食（IGP）。 这些复杂的喂养连接，预计模糊营养水平之间的区别，并导致预测，在丰富的通才捕食者的变化应该有最小的影响物种在食物网的基础。 因此，人们预计，营养级联应在陆地食物网与高IGP弱。 这项研究项目将测试这一假设在一系列的实地实验操纵蜘蛛在碎屑为基础的食物网的森林地面落叶。 在一系列实验中，将加强或减少爬行和织网蜘蛛，以测试蜘蛛对食草动物的捕食是否会引发影响落叶分解速度的营养级联。 第二组实验将操纵密度的食草动物和节肢动物捕食者的狼蛛，以确定是否资源限制是更有影响力的比IGP的人口动态丰富的通才捕食者。 这项研究将增加生态学的营养结构，控制过程和在一个共同的和重要的陆地食物网的间接影响的理解。

WiseDEB 9815842Terrestrial ecosystems typically contain species-rich assemblages of generalist predators. These predators not only prey upon lower trophic levels but also on other species of generalist predators, an interaction known as intraguild predation (IGP). These complex feeding connections are anticipated to blur distinctions between trophic levels and lead to the prediction that changes in abundances of generalist predators should have minimal effects on species at the base of food webs. As a consequence, it has been anticipated that trophic cascades should be weak in terrestrial food webs with high IGP. This research project will test this hypothesis in a series of field experiments manipulating spiders in the detritus-based food webs of forest-floor leaf litter. Cursorial and web-building spiders will be enhanced or decreased in one series of experiment to test if predation on detritivores by spiders initiates trophic cascades that affect the rates at which leaf litter decomposes. A second set of experiments will manipulate densities of detritivores and arthropod predators of the wolf spider to determine if resource limitation is more influential than IGP on the population dynamics of an abundant generalist predator. This research will increase ecological understanding of trophic structure, control processes and indirect effects in a common and important terrestrial food web.