Changes affecting the microbial activity in boreal coniferous forest humus and mineral soil layers after clear-felling were investigated by studying exoenzyme activities, microbial colony counts and community level physiological profiles, CLPPs. A recently clear-felled site and an old clear-felled site were compared with a standing forest site. The activities of exoenzymes in the humus layer increased 12 months after clear-felling. During this period, the amount of fungi increased in the humus layer as compared with that in the standing forest soil. The utilization potential of carbohydrates increased more than the utilization potential of amino acids and carboxylic acids in the humus layer of the new felled site. Immediate effects in the humus layer were followed by a 1-year delay of minor effects in the mineral layer. We showed that instant structural polymer degradation is initiated by a burst of exoenzymes in the humus layer. This effect was still observed in the old felled site seven years after felling.