DIRECT AND INTERACTIVE EFFECTS OF ENEMIES AND MUTUALISTS ON PLANT PERFORMANCE: A META-ANALYSIS

作者：William F. Morris, Ruth A. Hufbauer, Anurag A. Agrawal, James D. Bever, Victoria A. Borowicz, Gregory S. Gilbert, John L. Maron, Charles E. Mitchell, Ingrid M. Parker, Alison G. Power, Mark E. Torchin, Diego P. Vázquez · 发表于：Ecology · 年份：2007 · DOI：10.1890/06-0442 · 被引用次数：273 · 研究领域：Plant and animal studies、Plant Parasitism and Resistance、Ecology and Vegetation Dynamics Studies

Plants engage in multiple, simultaneous interactions with other species; some (enemies) reduce and others (mutualists) enhance plant performance. Moreover, effects of different species may not be independent of one another; for example, enemies may compete, reducing their negative impact on a plant. The magnitudes of positive and negative effects, as well as the frequency of interactive effects and whether they tend to enhance or depress plant performance, have never been comprehensively assessed across the many published studies on plant-enemy and plant-mutualist interactions. We performed a meta-analysis of experiments in which two enemies, two mutualists, or an enemy and a mutualist were manipulated factorially. Specifically, we performed a factorial meta-analysis using the log response ratio. We found that the magnitude of (negative) enemy effects was greater than that of (positive) mutualist effects in isolation, but in the presence of other species, the two effects were of comparable magnitude. Hence studies evaluating single-species effects of mutualists may underestimate the true effects found in natural settings, where multiple interactions are the norm and indirect effects are possible. Enemies did not on average influence the effects on plant performance of other enemies, nor did mutualists influence the effects of mutualists. However, these averages mask significant and large, but positive or negative, interactions in individual studies. In contrast, mutualists am...