Ecological Meltdown in Predator-Free Forest Fragments

The manner in which terrestrial ecosystems are regulated is controversial. The “top-down” school holds that predators limit herbivores and thereby prevent them from overexploiting vegetation. “Bottom-up” proponents stress the role of plant chemical defenses in limiting plant depredation by herbivores. A set of predator-free islands created by a hydroelectric impoundment in Venezuela allows a test of these competing world views. Limited area...