Effects of Elevated CO2 on a Chesapeake Bay (USA) Wetland
Li, J.H., Erickson, J.E., Peresta, G. and Drake, B.G. 2010. Evapotranspiration and water use efficiency in a Chesapeake Bay wetland under carbon dioxide enrichment. Global Change Biology 16: 234-245.
Results indicated that "although a decrease in stomatal conductance at elevated CO2 in the S. olneyi community was counteracted by an increase in leaf area index (LAI) to some extent, ET was still reduced by 19% on average over 12 years," while "in the S. patens community, LAI was not affected by elevated CO2 and the reduction of ET was 34%." With respect to NEE, they found that it "was stimulated about 36% at elevated CO2 in the S. olneyi community but was not significantly affected by elevated CO2 in the S. patens community." And merging the ET and NEE responses of the two species, they determined that "EWUE was increased about 83% by elevated CO2 in both the S. olneyi and S. patens communities."
In light of their several findings, Li et al. conclude that rising concentrations of atmospheric CO2 "could have significant impacts on the hydrologic cycles of coastal wetlands," noting that "reduced ET could increase carbon uptake by mitigating the effects of drought on carbon uptake (Rasse et al., 2005)," and that it "could also facilitate ground water recharge to counteract salinity intrusion in coastal areas caused by rising sea levels from global warming," stating that salinity intrusion has been identified as "a serious problem in the United States" based on the work of Stevenson et al. (1988) and Day et al. (2000).
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Rasse, D.P., Peresta, G., Saunders, C.J. and Drake, B.G. 2005. Seventeen-years of elevated CO2 exposure in a Chesapeake Bay Wetland: sustained but contrasting responses of plant growth and CO2 uptake. Global Change Biology 11: 369-377.
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