MODELING THE INFLUENCE OF HYDROLOGICAL PROCESSES ON SPATIAL AND TEMPORAL PATTERNS OF CO2 SOIL EFFLUX FROM AN ARCTIC TUNDRA CATCHMENT

Spatial and temporal patterns of CO? efflux from arctic tundra soils a re examined with three, linked simulation models at a 2.2-km(2) catchm ent. The model complex runs on a 2020 m grid and a temporal resolutio n of 1 h over one growing season. TOPMODEL is used to predict the dyna mics of the water balance and spatial pattern of water table. A canopy model (GAS-FLUX) is used to predict moss and vascular plant transpira tion rates. Soil respiration is computed from an empirical regression model incorporating the effects of soil temperature and depth to the w ater table. Soil efflux in the riparian zones of 60 g C m(-2) compares tn 119 g C in the hillslopes indicating large spatial differences. An increase of air temperature and solar radiation or a decrease of prec ipitation increase soil respiration, The results indicate a tight conn ection between water and carbon cycles at the catchment scale. Keeping all other conditions constant, a seasonal increase of transpiration r ates by 10% increases soil respiration by 5% or 4.6 g C m(-2). Data de ficiencies and suggestions for future modeling are discussed.