Effects of thinning and fertilization on wood properties and economic returns for Norway spruce

The effects of silviculture on wood and tracheid properties, and economic returns of Norway spruce (Picea abies (L.) Karst.) were investigated in two case studies, one comparing different thinning intensity in southeastern Finland and the other considering the effects of optimal nutrient addition in northern Sweden. Models for predicting the wood and tracheid properties of Norway spruce were integrated into a distance-independent process-based growth and yield model. Increasing the thinning intensity resulted in a lower mean wood density, tracheid length, and latewood proportion in harvested wood. Wood density and tracheid length of harvested pulpwood slightly decreased in later thinnings and final cuts. Thinning regimes with high early growing stock and decreasing later growing stock were most profitable. Nutrient addition accelerated volume growth and increased the value growth. The increase in volume growth due to nutrient addition more than offset the economic influence of the loss in wood density and tracheid length.