Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
Ecol Lett. 2010 Feb;13(2):202-12. doi: 10.1111/j.1461-0248.2009.01420.x. Epub 2009 Dec 29.
Predicting herbivore control over plants (i.e. changes in plant mass due to herbivore damage) is a central goal of ecology. Progress has been limited, however, because the vegetation characteristics thought to influence herbivore control are naturally correlated and typically experimentally confounded. To address this problem, we defined eight conventional models that predict herbivore control over plant community mass, each model based on a different vegetation characteristic (i.e. host concentration, tissue nitrogen, growth rate, size, tolerance of herbivory or net primary productivity). We then used structural equation modelling to test each model against two field experiments. Our results clearly rejected all models except for a tolerance of herbivory mechanism; stems with greater access to limiting resources better tolerated herbivory, regardless of where herbivore activity was greatest. Consequently, herbivore reductions of plant community mass were greatest at low resource availability. This adds to evidence that herbivore activity poorly predicts herbivore control.
预测食草动物对植物的控制作用（即食草动物对植物质量造成的变化）是生态学的一个核心目标。然而，由于被认为影响食草动物控制作用的植被特征是自然相关的，且通常在实验上是混淆的，因此进展受到了限制。为了解决这个问题，我们定义了八个预测植物群落质量的常规模型，每个模型都基于一个不同的植被特征（即宿主浓度、组织氮、生长率、大小、对食草动物的耐受性或净初级生产力）。然后，我们使用结构方程模型对两个野外实验进行了每个模型的测试。结果清楚地排除了除了一种对食草动物耐受性机制以外的所有模型；无论食草动物活动最强烈的地方在哪里，拥有更多获取限制资源的茎对食草动物的耐受性更强。因此，在资源供应不足的情况下，植物群落质量受到的食草动物减少量最大。这进一步证明了食草动物的活动并不能很好地预测食草动物的控制作用。
