Our objectives were to determine both spatial and temporal variations in soil respiration of a mixed deciduous forest, with soils exhibiting contrasting levels of hydromorphy. Soil respiration (RS) showed a clear seasonal trend that reflected those of soil temperature (TS) and soil water content (WS), especially during summer drought. Using a bivariate model (RMSE=1.03), both optimal soil water content for soil respiration (WSO) and soil respiration at both 10 °C and optimal soil water content (RS10) varied among plots, ranging, respectively, from 0.25 to 0.40 and from 2.30 to 3.60 μmol m−2 s−1. Spatial variation in WSO was related to bulk density and to topsoil N content, while spatial variation in RS10 was related to basal area and the difference in pH measured in water or KCl suspensions. These results offer promising perspectives for spatializing ecosystem carbon budget at the regional scale.