A meta-analysis of the effects of global environmental change on plant-herbivore interactions

Global environmental changes are hypothesized to affect herbivores indirectly via changes in plant defenses, and many studies have been conducted to explore effects of environmental change on plant chemistry and herbivory. We quantitatively synthesized data from these studies to produce generalities about the effects of a broad array of environmental changes on herbivores. Since conversion of natural habitat to agriculture has been one of the most profound environmental changes over the past century, the effects of global change variables on plant defense were also compared between natural and agricultural systems. We found evidence that increasing CO2, light availability, and nutrients all consistently increase herbivory, particularly by generalists. No significant differences in chemistry and herbivory response variables were found between natural and managed systems. Overall, these results are consistent with recent predictions of a disruption of natural trophic interactions with global change.