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 are examined with three, linked simulation models at a 2.2-km(2) catchment. The model complex runs on a 20*20 m grid and a temporal resolution of 1 h over one growing season. TOPMODEL is used to predict the dynamics of the water balance and spatial pattern of water table. A canopy model (GAS-FLUX) is used to predict moss and vascular plant transpiration rates. Soil respiration is computed from an empirical regression model incorporating the effects of soil temperature and depth to the water 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 precipitation increase soil respiration, The results indicate a tight connection between water and carbon cycles at the catchment scale. Keeping all other conditions constant, a seasonal increase of transpiration rates by 10% increases soil respiration by 5% or 4.6 g C m(-2). Data deficiencies and suggestions for future modeling are discussed.