PARENT SESSION
Oral Session # 41: Herbivory III: Forests and Soils.
Presiding: R Jones
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 103.

Foliar quality and herbivory as predictors of litter quality under elevated CO₂ conditions in a scrub-oak community.

Hall, Myra ^*,1, Stiling, Peter², Moon, Daniel², Hunter, Mark¹, ¹ University of Georgia, Athens, GA² University of South Florida, Tampa, FL

ABSTRACT- Atmospheric CO₂ concentrations have increased over the last century and continuing increases are expected to have significant effects on ecosystems. We studied interactions among atmospheric CO₂, foliar quality, litter quality, and herbivores within a scrub oak community. Sixteen plots of open-top chambers were followed; eight of which were exposed to ambient levels of CO₂ (350 ppm), and eight of which were exposed to elevated levels of CO₂ (700 ppm). We focused on three oak species, Quercus geminata, Quercus myrtifolia, Quercus chapmanii, and one nitrogen fixing legume, Galactia elliottii. Our results thus far indicate that the links between the chemistry of green foliage and leaf litter are very weak. We also looked at six insect groups on green foliage and found that damage decreased under elevated CO₂ conditions for four of the groups. In leaf litter we examined undamaged, chewed and mined leaves. Undamaged litter was lower in nitrogen and higher in C:N ratios than was litter damaged by leaf chewers and leaf miners. The overall increase in litter quality due to herbivore damage and the decrease in herbivore damage under elevated CO₂ treatments suggests that herbivory is a strong predictor of litter quality under elevated CO₂ conditions. Given the current rate of CO₂ increase, it is important to determine general predictions for modeling ecosystem processes under such environmental changes. We hope to be able to assess whether herbivore-mediated changes in litter quality under elevated CO₂ influence essential ecosystem processes.

Key words: herbivory, elevated carbon dioxide, foliar quality, litter quality