SMALL-SCALE HYDROLOGICAL VARIATION DETERMINES LANDSCAPE CO2 FLUXES IN THE HIGH ARCTIC

Abstract

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. © Springer Science+Business Media B.V. 2006.