Spatial and interannual variability of trace gas fluxes in a heterogeneous High Arctic landscape

• Summertime measurements of CO2 and CH4 fluxes were carried out over a range of high-arctic ecosystem types in the valley Zackenbergdalen since 1996 using both chamber and eddy covariance methodology. The net ecosystem CO2 exchange and CH4 flux data presented reveal a high degree of inter-annual variability within the dominant vegetation types in the valley, but also show distinct differences between them. In particular, the wet and dry parts of the valley show distinct differences. In general, the wet parts of the valley, the fens dominated by white cotton grass Eriophorum scheuchzeri, show high productivity, also in comparison with other sites, whereas CO2 uptake rates in the white arctic bell heather Cassiope tetragona and mountain avens Dryas spp.-dominated heaths are much smaller. Also within the different ecosystem types, a high degree of spatial variability can be documented. The spatial variability both within and between ecosystem types is especially pronounced for the CH4 flux and can, at least partly, be related to differences in vegetation composition and water table level. The importance of the CH4 emission from the various ecosystem types is evaluated both in relation to carbon and greenhouse gas budgets. In both wet and drier ecosystem components, inter-annual variability seems best explained through differences in the amount and distribution of snow in spring and the length of the growing season. A large number of replicate chamber measurements carried out over various vegetation types in the valley are used to produce a synthesis of 10 years of flux data available on growing season carbon dynamics and CH4 emission patterns in the individual parts of this high-arctic ecosystem and relates the differences between the ecosystems found in Zackenbergdalen to comparable sites in the circumpolar North.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Naturgeografi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Physical Geography (hsv//eng)

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