HR: 0830h
AN: B51D-0991    [PDF]
TI: Sixteen-year stimulation of sedge density by elevated CO$_{2}$ reaches 100% and is salt-stress enhanced.
AU: * Rasse, D P
EM: daniel.rasse@grignon.inra.fr
AF: Institut National de la Recherche Agronomique, INRA-INAPG, Bƒtiment EGER, Thiverval-Grignon, 78850 France
AU: Drake, B G
EM: drakeb@si.edu
AF: Smithsonian Environmentlal Research Center, PO Box 28,, Edgewater, MD 21037 United States
AB: Increased atmospheric CO$_{2}$ concentration produces a short-term stimulation of plant growth across terrestrial ecosystems. However, the long-term response remains uncertain and is thought to depend on environmental constraints. In the longest experiment on natural ecosystem response to elevated CO$_{2}$, we observed for the wetland sedge {\it Scirpus olneyi} that the shoot-density stimulation by elevated CO$_{2}$ increased from 16% during the first four years to more than 100% in the 16th year. While most of the inter-annual variability of the stimulation was explained by this steady increase with time (r2 = 0.89), the residuals of this variability were positively correlated with the salinity of the marsh (r2 = 0.44). These results demonstrate that the inter-annual variability of plant response to elevated CO$_{2}$ is coupled to environmental stress and indicate that experiments based on more than a decade of measurements are necessary to ascertain such effects.
DE: 0315 Biosphere/atmosphere interactions
DE: 0614 Biological effects
DE: 1615 Biogeochemical processes (4805)
DE: 1630 Impact phenomena
SC: Biogeosciences [B]
MN: 2003 Fall Meeting