Small-scale hydrological variation determines landscape CO2 fluxes in the high Arctic
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We explored the influence of small-scale spatial variation in soil moisture on CO2 fluxes in the high Arctic. Of five sites forming a hydrological gradient, CO2 was emitted from the three driest sites and only the wettest site was a net sink of CO2. Soil moisture was a good predictor of net ecosystem exchange (NEE). Higher gross ecosystem photosynthesis (GEP) was linked to higher bryophyte biomass and activity in response to the moisture conditions. Ecosystem respiration (R e) rates increased with soil moisture until the soil became anaerobic and then R e decreased. At well-drained sites R e was driven by GEP, suggesting substrate and moisture limitation of soil respiration. We propose that spatial variability in soil moisture is a primary driver of NEE.
KeywordsHigh Arctic Carbon dioxide fluxes Spatial variability Soil moisture Vegetation
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This research was funded by the European Commission Framework 5 grant no: EVK2-CT-2002–00145 (FRAGILE). We are grateful to the University Centre on Svalbard (UNIS) for logistical support. We also thank Jani Mannikko, Katrin Sjögersten and Richard Ubels for fieldwork assistance, Ad Huiskes for chemical analysis of soil C and N, and Steve Palmer for providing critical statistical support.
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