Ecosystem services in cacao agroforestry: predation by birds, bats and ants on spiders and insect herbivores

在初级生产力高、食物网简单的农业生态系统中，节肢动物通过捕食调节食草动物的行为是非常重要的。最近的研究测试的影响，自上而下的生态控制，消除或排除捕食者集中在一个捕食者群体，通常是脊椎动物或无脊椎动物。杂食性通常被忽视，更高的营养水平对蜘蛛等中间捕食者的影响也是如此。在为期两年的全析因实验结合鸟类，蝙蝠和蚂蚁排除，我们将操纵最重要的脊椎动物和无脊椎动物捕食者群体在印度尼西亚可可农林。地块的遮荫条件和与天然森林的距离不同，这些变量已知会影响食虫鸟类群落。草食动物以及蜘蛛和昆虫草食动物区系的组成和生物量将被量化，使我们能够解开食物网。时间变化的相对贡献的动物材料和蜜露蚂蚁饮食将分析使用纵向数据的天然稳定同位素组成的未成熟的蚂蚁从巢收集。总之，这些数据将提供一个独特的洞察掠夺性食物网，提供自上而下的生态控制在热带农林系统，并进入他们的空间和时间的变化。

Arthropod herbivore regulation by predation is expected to be important in agro-ecosystems where primary productivity is high and food webs are simple. Recent studies testing the effects of top-down ecological control by removing or excluding predators concentrate on one predator group, generally either vertebrate or invertebrate. Omnivory is generally ignored, as is the impact of higher trophic levels on intermediate predators such as spiders. In a two-year full factorial experiment combining bird, bat and ant exclusions, we will manipulate the most important vertebrate and invertebrate predator groups in Indonesian cacao agroforests. Plots will differ in shading conditions and distance to natural forest, variables known to affect insectivorous bird communities. Herbivory as well as the composition and biomass of the spider and insect herbivore fauna will be quantified, allowing us to disentangle the food webs. Temporal variation in relative contribution of animal material and honeydew to ant diet will be analysed using longitudinal data on natural stable isotope composition of immature ants collected from nests. Together, these data will provide a unique insight into predatory food webs which deliver top-down ecological control in tropical agroforestry systems, and into their spatial and temporal variability.