How Wood Quality Can Be Shaped: Results of 70 Years of Experience

This experiment was conducted in the pine woods of central Europe at a research area established in 1951. The experimental area of 1.35 ha was set up in a 14-year-old pine tree stand, which was divided into lots, and the pruning procedure took place in different variants. Some lots constituted control lots without pruned trees. The trees were pruned in four variants, reducing the living tree crown by 1/4, 1/3, 1/2, and 2/3 of its length. The study's main aim was to determine the influence of pruning forest trees on the tree tissue. Moreover, the study attempted to answer whether pruning was a significant procedure for wood valorisation, and if yes, then which variant was the optimal one for Scots pine growing on the European plain. The results indicated a significant impact of pruning young pine tree stands on the properties of wood tissue, which differed regarding the adopted pruning variant. Significant differences in the width of annual rings, the size of the particular areas of the annual rings (latewood or earlywood), and the wood density depending on the pruning variant were observed. Furthermore, the results indicated that pruning induced numerous processes, which optimised the physiological and mechanical functions of the tree trunks. The outcome of this optimisation was, among others, the diversification of the vascular and strengthening area of the annual ring as well as the wood density, which was a reaction to reducing a part of the assimilation apparatus. From the technical wood value viewpoint, the optimal pruning variant for pine was between 1/3 to 1/2 of the living crown.