2008 Joint Annual Meeting (5-9 Oct. 2008): An Experimental Test of Nine Climate Change Scenarios on Trace Gas and Carbon Dynamics in a Minnesota Bog and Fen over Eight Years.
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774-3 An Experimental Test of Nine Climate Change Scenarios on Trace Gas and Carbon Dynamics in a Minnesota Bog and Fen over Eight Years.



Wednesday, 8 October 2008: 2:00 PM
George R. Brown Convention Center, 372B
Scott Bridgham, University of Notre Dame, Center for Ecology&Evolutionary Bio, 5289 University of Oregon, Eugene, OR 97403-5289, John Pastor, Dept. of Biology, Univ. of Minnesota, Duluth, MN 55812, Jeffrey White, Biogeochemical Lab & Center for Res. in Environ. Sci., Indiana Univ., Bloomington, IN 47405, Jake Weltzin, USA National phenology Network, 1955 East 6th St., Tucson, AZ 37996 and Robert Shannon, Pennsylvania State Univ., 233 Agric. Engineering Bldg., Penn State University, University Park, PA 16802
We constructed a large mesocosm facility in northern Minnesota to examine the effects of climate change on peatlands.  Twenty-seven intact peat monoliths (2.1 m2, 60-cm depth) were removed each from a bog and intermediate fen and subjected to three infrared-loading treatments and three water-table treatments for eight years.  Ecosystem respiration as CO2 flux increased with warmer soil temperatures, but this effect decreased substantially over several years, suggesting the exhaustion of a labile soil pool.  CH4 fluxes were dependent on both water-table level and soil temperature, but the effect of water table was much greater in the fen mesocosms, suggesting an enhanced potential for methanotrophy in the fen.  The indirect effects of the water-table and warming treatments on CH4 fluxes were as much through indirect effects on porewater chemistry as through the expected direct effects.

We integrated carbon responses as net carbon gain or loss for the various treatments.  Fen plots either had no change or were losing carbon, whereas the bogs gained carbon.  Wetter conditions enhanced carbon storage in the bogs and reduced carbon losses in the fens.  Rapid initial vertical peat accumulation in the wet bog treatments caused the water-table elevation to decrease in these plots over time, and this fed back into a large decrease in carbon storage rates.  These effects on carbon fluxes in the bog mesocosms were largely due to water-table effects on moss net primary production, whereas the effects in the fen appeared to be due to multiple factors.  Our results suggest large effects of climate change on carbon dynamics and trace gas emissions in peatlands, with important ecosystem feedbacks determining the trajectories of response.

See more of: Symposium --Stability of Peatland Soil Carbon Pools and Trace Gas Emissions to Disturbance
See more of: S10 Wetland Soils