The proposed research will investigate the effects of insect herbivory on rates and patterns of species replacement during primary plant succession on sand dunes. The research will focus on a specialist beetle, Altica bimarginata, and the willow, Salix cordata. An integrated set of field and greenhouse experiments will examine both the effects of plant successional stage on rates of herbivory and effects of herbivores on plant successional processess, as well as provide critical tests of the underlying mechanisms. To study how herbivore abundance varies between and within plant successional stages, field experiments will examine how attributes of host plants and the surrounding plant community influence herbivory. The role of genetic differences between plants in influencing rates of herbivory will be addressed with a reciprocal transplant study. Herbivore exclusion experiments will examine the role of herbivory in influencing plant successional patterns. The importance of surrounding plant neighbors in influencing succession and how herbivores affect succession will be studied with plant neighbor removal experiments. Greenhouse experiments varying the level of herbivory will examine what aspects of host plant fitness are affected by herbivory. Although herbivory is known to strongly affect plant fitness and competitive interactions, the role of herbivory in influencing plant succession has been largely ignored. By focusing on both the effects of plants on insects and the effects of insects on plants, the interactive nature of insect-plant dynamics in successional systems will be elucidated. These contributions are of central importance to insect and plant ecology, as well as understanding of communities and factors controlling species diversity.
