The effect of different nitrogen doses and cutting on the rate of physiological and growth processes has been studied in birch forests of blueberry type in taiga zone. It has been established that nitrogen has got little effect on the vitality and growth of spruce in mature birch forests because of the light lack. In thinned stands the nitrogen increases the rate of photosynthesis twofold, activates processes associated with the accumulation and subsequent outflow of carbon metabolites from the needles. The result of this nitrogen action is the intensification of growth processes.