| I examine the effects of insect herbivory on plant communities, and the properties of plant communities that regulate those effects, with an emphasis on the role of insect herbivory in rough fescue prairie. I begin with a meta-analysis of studies that have chemically suppressed insects in herbaceous plant communities, and measured its effect on primary production. Effect size did not depend upon productivity or plant species richness, but did depend upon community type. Next I examine the consequences of insect suppression in the rough fescue prairie of Kinsella Ranch, Alberta, in the aspen parkland ecoregion. Insects did not alter primary production or focal plant performance, but in the second year of the study (and of a drought), insects reduced canopy cover and species richness. I conclude that insect herbivory affects community structure, at least under drought conditions. Lastly, I show that the soil insect herbivores at this site were at low densities unlikely to have affected plant growth. |
