Fig. 1

Growth response of spruce stand when the nitrogen dose is 100, 200, 300 or 400 kg ha^-1. In this example, the dominant height of the stand is 20 m, number of trees per hectare is 800 and site index is 27 m (left). The diagram on the right shows the total response when calculated from the annual responses (Annual) or from the responses of the 3^rd and 8^th year, corresponding to the first and second 5-year period