135-1 Will Wetlands Amplify or Attenuate Climate Change In Response to Elevated Carbon Dioxide?.

See more from this Division: S10 Wetland Soils
See more from this Session: William H. Patrick, Jr. Memorial Lectureship/Div. S10 Business Meeting
Monday, November 1, 2010: 9:40 AM
Long Beach Convention Center, Room 306, Seaside Level
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J. Patrick Megonigal, 647 Contees Wharf Rd, Smithsonian Environmental Research Center, Edgewater, MD
Wetlands influence climate because they hold a large pool of soil organic carbon and are a strong source of methane gas. Likewise, changes in climate and other global factors have important implications for the delivery of wetland ecosystem services. I will review research on wetland responses to rising CO2, with particular attention to effects on the balance between soil carbon sequestration and methane emissions. Elevated CO2 experiments in peatlands, non-tidal and tidal marshes, and rice paddies demonstrate perturbations of the greenhouse gas balance that vary strongly across ecosystem types. Elevated CO2 generally stimulates photosynthesis and growth in temperate wetlands, but results are equivocal for peatlands. In wetland forests and tidal wetlands, a portion of the elevated CO2-enhanced or ‘excess’ plant production is sequestered in long-term pools such as wood or soil organic matter. The implications of increased soil carbon sequestration for tidal wetlands are profound because the process affects their ability to gain elevation as sea level rises and avoid conversion to open water. The positive effects of elevated CO2 on tidal marsh elevation gain are diminished by soil nitrogen fertilization, indicating that elevated CO2 will interact with other global changes such as eutrophication. The largest portion of the additional plant matter produced at elevated CO2 is rapidly recycled in plant and microbial respiration, including methanogenesis. Elevated CO2 studies report an increase in CH4 emissions, potentially offsetting the decrease in radiative forcing expected from increased plant growth. More elevated CO2 research is needed in peatlands, freshwater marshes, and forested wetlands. Progressive experimental designs should seek to understand how elevated CO2 interacts with other global change factors such as sea level rise, eutrophication, elevated temperature, and invasive plant species.
See more from this Division: S10 Wetland Soils
See more from this Session: William H. Patrick, Jr. Memorial Lectureship/Div. S10 Business Meeting