EFFECTS OF HERBIVORES ON GRASSLAND PLANT DIVERSITY

The role of herbivores in controlling plant species richness is a crit ical issue in the conservation and management of grassland biodiversit y. Numerous field experiments in grassland plant communities show that herbivores often, but not always, increase plant diversity. Recent wo rk suggests that the mechanisms of these effects involve alteration of local colonization of species from regional species pools or-local ex tinction of species, and recent syntheses and models suggest that herb ivore effects on plant diversity should vary across environmental grad ients of soil fertility and precipitation.