PARENT SESSION
Poster Session #49: Elevated CO₂ II.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Plant-insect interactions in a forest community exposed to free-air CO₂ enrichment.

KNEPP, RACHEL^*,1, HAMILTON, JASON², DELUCIA, EVAN¹, ¹ University of Illinois, Urbana, Illinois² Ithaca College, Ithaca, New York

ABSTRACT- Increased atmospheric CO₂ concentration alters leaf structure and chemistry, but how these changes affect leaf herbivory in a complex multi-species forest community is largely unknown. Leaf damage was quantified on 12 species of hardwoods planted in the understory of a loblolly pine plantation in North Carolina. Seedlings were exposed to free-air CO₂ enrichment (FACE) under ambient (370 ppm) or elevated (570 ppm) [CO₂]. Elevated atmospheric CO₂ did not affect the abundance or oviposition preference of herbivorous insects, and there was no significant overall effect on the percentage leaf area damaged by insects. However, among damaged leaves, the number of Quercus alba leaves damaged decreased by 59% (P < 0.06) under elevated [CO₂]. This indicates that although insects consume the same amount of foliage regardless of CO₂ concentration, those that consume Q. alba feed on fewer leaves in larger amounts. A shift in the pattern of herbivory under elevated atmospheric [CO₂] may alter the predicted increase in carbon gain.

KEY WORDS: herbivory, forest, understory, hardwood