Global signal of top-down control of terrestrial plant communities by herbivores

The theory of “top-down” ecological regulation predicts that herbivory suppresses plant abundance, biomass, and survival but increases diversity through the disproportionate consumption of dominant species, which inhibits competitive exclusion. To date, these outcomes have been clear in aquatic ecosystems but not on land. We explicate this discrepancy using a meta-analysis of experimental results from 123 native animal exclusions in natural terrestrial ecosystems (623 pairwise comparisons). Consistent with top-down predictions, we found that herbivores significantly reduced plant abundance, biomass, survival, and reproduction (all P &lt; 0.01) and increased species evenness but not richness (P = 0.06 and P = 0.59, respectively). However, when examining patterns in the strength of top-down effects, with few exceptions, we were unable to detect significantly different effect sizes among biomes, based on local site characteristics (climate or productivity) or study characteristics (study d...“自上而下”生态调控（top-down ecological regulation）理论预测，植食作用会抑制植物的多度、生物量与存活率，但可通过优先取食优势种提升物种多样性，从而阻碍竞争排除。迄今为止，这类调控效应在水生生态系统中已得到明确验证，但陆地生态系统中尚未获得一致结论。我们针对自然陆地生态系统中123项本土动物排除实验（共623组配对比较）的结果开展元分析（meta-analysis），以此阐释这一认知差异。研究结果与自上而下调控的预测相符：植食动物显著降低了植物的多度、生物量、存活率与繁殖率（所有P值均<0.01），并提升了物种均匀度，但未显著影响物种丰富度（对应P值分别为0.06与0.59）。然而，在探究自上而下效应的强度模式时，除极少数例外情况，基于局地生境特征（气候或生产力）或研究特征（研究设计……），我们未检测到不同生物群系间存在显著差异的效应量。