Intensive studies on trace gas emission from a subarctic Swedish peatland.

Subarctic peatlands are one of the most sensitive ecosystems which react in a direct way to climate warming. Already now we can observe how formations underlain by permafrost are rapidly disintegrating and changing into a wetter hydrological state. These changes have triggered visible and substantial changes in the vegetation distribution and may represent an important feedback mechanism in changing climate through changes in the land-atmosphere exchanges of trace gases such as carbon dioxide (CO2) and methane (CH4).Within this study intensive and detailed flux measurements of both CH4 and CO2 were conducted during 2006 and 2007 over Stordalen mire, northernmost part of sub-Arctic Sweden (68° 20' N, 19° 03' E, alt. 351 m). Measurements were conducted with the use of two different techniques, automatic chambers and eddy correlation using a tunable diode laser. Landscape scale fluxes were documented by the eddy correlation system to be rather high, averaging 9 mg m-2 hr-1 during the peak season and these fluxes corresponded well with automatic chamber measurements in the wet minerotrophic parts of the peatland. It is the latter vegetation type that is expanding as the permafrost is melting. Apart detailed comparison between the results obtained with both techniques a full annual budget for the exchanges of radiative active trace gases between this mire and the atmosphere will be presented.