Does plant diversity increase top–down control of herbivorous insects in tropical forest?

Higher trophic level interactions are key mediators of ecosystem functioning in tropical forests. A rich body of theory has been developed to predict the effects of plant diversity on communities at higher trophic levels and the mechanisms underlying such effects. The ’enemies hypothesis’ states that predators exert more effective top–down control of herbivorous insects with increasing plant diversity. Support for this hypothesis has been found in temperate forests and agroecosystems, but remains understudied in tropical forests. We compared incidence of attacks of different natural enemies using artificial caterpillars in a tropical forest landscape and investigated the role of plant community structure (i.e. species richness, composition and density), and the role of forest fragmentation (i.e. patch size, edge distance and canopy openness) on predation intensity. Plant community effects were tested with respect to three vegetation strata: trees, saplings and herbs. Observed predation ...热带森林中，较高营养级（trophic level）的种间相互作用是生态系统功能的关键调控因子。学界已构建起丰富的理论体系，用以预测植物多样性对较高营养级群落的影响及其内在作用机制。"天敌假说（Enemies Hypothesis）"指出，随着植物多样性升高，捕食者对植食性昆虫的下行控制（top–down control）作用会更强。该假说已在温带森林与农业生态系统中得到验证，但在热带森林中的相关研究仍较为匮乏。本研究在热带森林景观中利用人工毛虫（artificial caterpillars），对比了不同天敌对植食性昆虫的攻击发生率，并探究了植物群落结构（即物种丰富度、组成与群落密度）以及森林片段化（forest fragmentation）特征（即斑块面积、边缘距离与林冠开度（canopy openness））对捕食强度的影响。研究针对乔木层、幼树层与草本层这三类植被层（vegetation strata），检验了植物群落的作用效应。本次观测到的捕食活动……