Treatment to reduce density, from 19 000 stems/ha to about 1642 stems/ha at a regular spacing of 2.4 × 2.4 m, in a young balsam fir (Abiesbalsamea (L.) Mill.) stand stimulated carbon mineralization rates of the litter layer which were, in turn, positively correlated with inorganic nitrogen levels. Increased carbon mineralization rates were attributed to increased summer temperatures in the litter layer. Temperature measurements under the snow indicated a consistently lower winter temperature in the treated stand as compared with the control. The increased and more regular spacing in the treated stand resulted in more rapid basal area growth, increased needle weights, and greater foliar N concentrations, reflecting an increased nitrogen uptake by the trees.