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Arctic Biosphere Atmosphere Coupling at Multiple Scales

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Hypothesis 6: Landscape fluxes of methane

CH4 is an important greenhouse gas, but the net fluxes (reflecting both methanogenesis and methanotrophy) are patchy in space and time, largely related to soil moisture regime (and thus topography and vegetation type), and are likely to be sensitive to warming (Sjögersten & Wookey 2002b). CH4 fluxes on dry-mesic tundra sites are low, and generally negative (indicating net CH4 oxidation by methanotrophs) (Christensen et al., 1999), while small lakes and mires act as “hot spots” for CH4 emissions (Svensson et al., 1999). The implications of flux variability on landscape net emissions are poorly understood. We will generate regional flux estimates from multi-scale measurements in a sampling framework that incorporates landscape variability and cuts across environmental gradients.

H6: The magnitude and direction of net CH4 fluxes reflect soil moisture status, temperature, and SOM content. Contrasting landscape positions will therefore respond differentially to temporal variability in the abiotic environment.

WP2 will make chamber headspace measurements of CH4 fluxes by gas chromatography, while WP5 will measure continuous CH4 concentrations over the landscape via a laser and determine CH4 concentrations in atmospheric profiles via sampling from the aircraft.

Outcome: Improved determination of landscape fluxes of CH4 and critical biological/physical drivers.

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Last modified: 26 Jan, 2006
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