Brian Smeets

SHIFTS IN HERBIVORY PREFERENCE WITH ELEVATED CARBON DIOXIDE AND NITROGEN ENRICHMENT. Brian Smeets¹, Nicole Miller^1,2, Tiffany Knight^1,2. Environmental Studies, Washington University in St. Louis.² Department of Biology, Washington University, St. Louis, MO¹.

Identifying processes affected by a shift in carbon and nitrogen availability will allow us to predict potential changes in plant species composition. Competition and Herbivory are two major factors which affect the relative abundance of species in plant communities (del Val 2005). The goal of our study is to understand how changes in carbon dioxide and nitrogen availability, as well as the diversity of other plants in the community, will alter (1) foliar chemistry of plants (e.g., C:N ratios), (2) incidence of herbivory, (3) composition of herbivores, and (4) plant fitness. Plant species within different functional groups are known to respond differentially to elevated CO₂and N, and thus we consider several species from each functional group. Our study included eight species of flowering forbs: Achillea millefolium, Amorpha canescens, Anemone cylindrica, Asclepias tuberosa, Lespedeza capitata, Lupinus perennis and Petalostemum villosum. Our study was conducted at the University of Minnesota’s BIOCON site, a large-scale experiment designed to manipulate biodiversity (1, 4, 9, or 16 species plots), CO₂ (ambient, elevated) and N (ambient, elevated).