Predispersal seed predation in the limitation of native thistle

Abstract

Invertebrate herbivores, such as insects, have been hypothesized to be less important than vertebrates in plant population dynamics (Crawley, 1989). This generalization, if true, is an important one. However, few experimental data are available on the role of invertebrates in the recruitment and density of native plants. Also, few studies analyze both interactions simultaneously. The purpose of this study was to concurrently test the importance of three biological interactions that may limit plant densities. In three concurrent experiments, we excluded insects or vertebrates, or altered the level of seedling competition with established grasses.