Thinning Schedules for Spruce Stands

We investigate financial feasibility of a few thinning schedules for spruce stands. Some example stands have previously experienced commercial low thinning, whereas others young stand cleaning only. High thinning is combined with quality thinning, and further growth of trees is estimated using a Norwegian growth model. High capital return rates are gained by diameter-limit cutting to the transition diameter between pulpwood and sawlogs. Repeated thinnings lead to reduction in the capitalization during several decades, the system approaching a stationary state. The transient forest stands investigated shown a significant excess capital return, in relation to the stationary state, and this excess return is due to transient tree size distribution. Correspondingly, capital return rate gained in rotation forestry is somewhat higher than that of stationary continuous-cover forestry, and the volumetric yield is much higher. The productive capacity of stands previously thinned from below apparently has been ruined by that treatment.