The carbon and nitrogen mineralization dynamics ofPinus sylvestrisL. harvesting residues, when mixed with an acidic, nitrifying fen peat, were studied during aerobic, laboratory incubation at 20°C over 12 weeks. Green needle, brown needle and fine root showed a pattern of curvilinear decline in C mineralization rate with time. The total amounts of C mineralized from those residues, expressed as a percentage of their initial C content, were 52, 41 and 16%. Stem bark and stem wood mineralized more slowly; the value for stem bark was near zero. With the exception of stem bark, the harvesting residues enhanced the mineralization of added14C‐labelled glucose. During the early decomposition of the pine residues, the degree of net N immobilization of mineral N was related to the initial C/N ratio or total N concentration of the residues and net N mineralization was negatively correlated with mineralization of C. The remineralization rate of freshly immobilized N was estimated as seven times faster than the mineralization rate of the more recalcitrant native N from the fen peat. The added pine residues did not influence measurably the nitrification capacity of the fen peat.