HR: 11:20h
AN: B52C-05    [Abstracts]
TI: Environmental Controls on Methane Emission From Siberian wet Polygonal Tundra on Samoylov Island, Lena River Delta
AU: * Sachs, T
EM: torsten.sachs@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg A43, Potsdam, 14473, Germany
AU: Giebels, M
EM: m.giebels@gmx.de
AF: Institute of Geoecology, Technical University Braunschweig, Langer Kamp 19c, Braunchweig, 38106, Germany
AU: Boike, J
EM: julia.boike@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg A43, Potsdam, 14473, Germany
AU: Kutzbach, L
EM: kutzbach@uni-greifswald.de
AF: Institute of Botany and Landscape Ecology, Ernst Moritz Arndt University of Greifswald, Grimmer Strasse 88, Greifswald, 17487, Germany
AB: The carbon budgets of the atmosphere and terrestrial ecosystems are closely coupled by vertical exchange fluxes of carbon dioxide and methane. Arctic tundra ecosystems have been major carbon sinks throughout the Holocene, resulting in a globally significant but highly sensitive carbon reservoir. Large uncertainties about the current and future contribution of these environments to the global carbon cycle remain especially with regard to methane emissions. In order to address this uncertainty and analyze the complex network of coupled processes and interconnected controls of tundra carbon exchange, we combined intensive field studies on multiple spatial scales with process-based and statistical model approaches. Methane emissions on both ecosystem-scale and plot-scale were measured in northern Siberia covering the entire growing season from end of May until end of September 2006 by the eddy covariance method, and from July through September 2006 by closed chambers, respectively. Our study site was located in the southern part of the Lena River Delta, which is characterized by arctic continental climate and cold continuous permafrost. Closed chamber measurements of methane fluxes were conducted daily on 15 plots in four differently developed polygon centers and on a polygon rim. This study adds significant findings on methane emission at different scales in an area that is seriously underrepresented in current efforts to quantify carbon emissions from high latitude environments. Controls on methane emission were identified by applying models of differing complexity ranging from more deterministic to more empirical approaches. We found relatively low fluxes on the landscape scale, which were mainly controlled by soil temperature, near-surface turbulence, and air pressure. On the micro-site scale, fluxes varied strongly and were controlled by different sets of environmental parameters. The results may have implications for the widely used closed chamber method.
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
DE: 0490 Trace gases
SC: Biogeosciences [B]
MN: 2007 Fall Meeting