Finanzielle konsequenzen der fichtenastung

This paper analyses how to thin pruned spruce stands and how many spruces per hectare should be pruned from the economic point of view. This study is based up to an age of 48 years on data from a spruce thinning experiment located in Freising, which were completed with simulations up to an age of 98 years. After that, the payments caused by pruning were determined. In this calculation a loss of 20% of the pruned spruces was included. The whole valuation was repeated 1000 times with fluctuating timber prices. This way the mean and the dispersion of the net present value and the probability of losses caused by pruning could be determined for interest rates between 0% and 5%. With the help of the certainty equivalent, which connects the mean and the dispersion of the net present value, optimal numbers of pruned spruces per hectare could be determined. Comparing four variants of thinning, in most cases a strong thinning, combined with an early beginning of harvesting spruces after they have reached a diameter of 55 cm is financially advantageous. The three other variants of thinning were a weak support of the best trees combined with a following phase of thinning from below, a heavy thinning followed by a phase without any thinning until the final harvest and a non-thinned variant. In addition to this, it was found, that pruning of the 150 most vigorous spruces is optimal from the financial point of view. This variant was superior to pruning 50, 100, 200 or 250 spruces per hectare.