Dissertation Research: Regional/historical Influences and Top-down vs. Bottom-up Processes in Arthropod Community Structure

捕食者(“自上而下”)和资源(“自下而上”)的强烈直接影响正在从数学模型和简化的组合中显现出来。来自自然社区的数据是必要的，以提高我们对它们在多个尺度上的综合影响的理解。该项目采用大规模调查和现场操控实验相结合的方法，研究了夏威夷桃金娘的鸟类捕食者和节肢动物群落之间的营养相互作用。在火山基质年龄的400万年梯度上，养分的可获得性以单峰方式变化。Metrosideros上的节肢动物密度跟踪了整个岛链的这种关系，表明资源对系统的强大影响。物种多样性随地质年龄的增长而积累，与密度无关。这些关系将在年轻的玄武岩熔岩流上进行评估(120 yo.)在Metrosideros植物群落营养有限的地方，对施肥的反应是生产力提高了10倍。脊椎动物捕食者(鸟类)将被排除在外，大片土地将以完全交叉的、良好重复的设计进行施肥。拟议的研究计划将自然模式的观测数据的规模和视角与受控的野外实验相结合，从而扩大了仅从这两种方法中的任何一种方法进行推断的范围。

0073055TaylorEvidence of strong direct effects of predators ("top-down") and resources ("bottom-up") are emerging from mathematical models and simplified assemblages. Data from natural communities are necessary to improve our understanding of their combined effects over multiple scales. Using large-scale surveys combined with manipulative field experiments at a single site, this project examines the trophic interactions of avian predators and arthropod assemblages of the Hawaiian myrtaceous tree Metrosideros polymorpha. Across a four million-year gradient of volcanic substrate age, nutrient availability varies in a unimodal fashion. Arthropod densities on Metrosideros track this relationship across the island chain, suggesting a strong influence of resources to the system. Species diversity accumulates with geological age and is independent of density. These relationships will be evaluated on a young basaltic lava flow (120 y.o.) where Metrosideros plant communities are nutrient limited and respond to fertilization with a tenfold increase in productivity. Vertebrate predators (birds) are to be excluded and large plots will be fertilized in a completely crossed well-replicated design. The proposed research program combines the scales and perspectives of observational data on natural patterns with controlled field experiments, thereby expanding the scope of inference from either approach alone.