BELOTE, R. TRAVIS1,
JAKE F. WELTZIN1, and RICHARD J. NORBY2. Department
of Ecology and Evolutionary Biology University of Tennessee Knoxville, TN 37996
and Oak Ridge National Laboratory Oak Ridge, TN 37831-What are the effects
of elevated CO2 on a plant community dominated by two invasive
plants?
Rising levels of atmospheric
carbon dioxide (CO2) and invasions by non-native organisms are
predicted to change patterns and processes of native ecosystems in the near
future. Likewise, rising CO2 levels may increase the success of some
plant invaders. We are examining
species composition, aboveground production and biomass, and cover of the
understory plant community in ambient and elevated CO2 treatments in
an ongoing, free-air CO2 enrichment (FACE) facility on the Oak Ridge
National Environmental Research Park, Tennessee. Five 25-m diameter plots have
received either ambient (= control) or elevated (537 ppm) CO2 since
1998. The understory plant community in these plots is dominated by several
non-native plant species including Lonicera japonica and Microstegium
vimineum, two highly invasive plants in the Southeastern U.S. Results from the 2000 and 2001 growing
season indicate that M. vimineum (C4) cover and
production was about 50% greater in ambient CO2 plots than in
elevated CO2 plots (P£0.01). In
contrast, L. japonica (C3) cover was about 22% greater in
elevated plots than ambient plots (P£0.09). This pattern
suggests competitive interactions between the two invasive species. In summer 2001, we conducted a field ‘press’
competition experiment wherein we grew M. vimineum and L. japonica
alone and in competition and added a watering treatment to half the plots. We will discus the relationships between the
two invasive plants and the effect of elevated CO2 on invasive
species.