The nitrogen dynamics in decomposing needle litter incubated in a clear—cut area were seen to be very different from those of the same types of litter incubated in a mature forest. In each stand 10 different sets of Scots pine needle litter with different initial nitrogen concentrations were incubated. A nonlinear regression model of loss and nitrogen dynamics estimates that the C/N ratio above which net immobilization and below which net mineralization takes place differs significantly between the systems (109 in the mature forest and °63 in the clear—cut area).