PARENT SESSION
Oral Session #106: Plant Ecology: Global Climate Change.
Presiding: D. Breshears
Friday, August 9. 9:00 AM to 12:00 PM. Grand Ballroom East, Radisson.
Plant communities, exotic invaders, and the role of elevated CO2 .
Belote, R.*,1, Weltzin, Jake1, Norby, Richard2, 1 University of Tennessee, Knoxville, Tennessee2 Oak Ridge National Laboratory, Oak Ridge, Tennessee
ABSTRACT- Rising levels of atmospheric carbon dioxide (CO 2) and invasions by non-native organisms are predicted to change patterns and processes of ecosystems in the near future. Likewise, rising CO 2 levels may increase the success of some plant invaders. We are examining species composition, aboveground production, and cover of the understory plant community in ambient and elevated CO 2 treatments in a free-air CO 2 enrichment (FACE) facility on the Oak Ridge National Environmental Research Park. The understory plant community is dominated by several non-native invasive plant species including Lonicera japonica, a C 3 vine, and Microstegium vimineum, an annual C 4 grass. Results from the 2001 growing season indicate that L. japonica cover was 22% greater in elevated than ambient CO 2 plots. In contrast, M. vimineum cover and production was 50% greater in ambient than elevated CO 2 plots. We found a negative correlation between the two species under elevated but not ambient CO 2. This pattern suggests competitive interactions between the two invasive species under elevated CO 2. In summer 2001, we conducted a field competition experiment wherein we grew M. vimineum and L. japonica alone and together under ambient CO 2. Cover of L. japonica was 8 times greater in plots where M. vimineum was removed than in control plots. These data suggest M. vimineum interferes with L. japonica under ambient CO 2. Together these studies suggest that elevated CO 2 may shift species interactions from interference to competition.
KEY WORDS: elevated CO2, invasive species