Impact of thinning on the growth and yield of Scots pine stands – a case study from Kazlų Rūda (Lithuania)

Pilnas tekstas lenkų kalbaOne of the main tasks for the forest managers is to form the highly productive stands, and it is mainly performed by applying intermediate cuttings during the stand development. As the impact of thinning on the premature Scots pine, commercially most important species in Lithuania, has not been sufficiently investigated yet, our objective was to evaluate the impact of such treatments on the growth and yield of the pine stands by using data from the long term experimental plots. The described thinning experiment was established in 1983 in Kazlų Ruda (54.760395°N, 23.517736°E), in the 30−years−old Scots pine forest, growing in oligotrophic site conditions. Four square plots with the size of 0.25 ha each were set. The first one (5) was left as a control variant with no thinning, while the others were subjected to the treatments of different intensity. In variant 5A (slightly thinned) 15% of the basal area compared to the control plot was removed. Accordingly, in variant 5B (moderate thinning) 25% and in variant 5C (heavy thinning) 40% of basal area was subtracted. No additional thinning was implemented further during the experiment. Plots were remeasured at least 4 times with the last measurement in 2016, when the stand was 63 years old. The main result of this study was that after the 33 years no evident effect of various intensity of silvicultural treatments can be seen as the growth and yield of the unthinned forest stand was the highest compared to the thinned ones. Growth and yield in the most intensely thinned stand reached 86 and 85% compared to the control variant, respectively. The best productive results were found for moderate thinning (92 and 89% of growth and yield of the unthinned stand), while the worst – in the slightly thinned 5A variant (77 and 83% of values for the control stand). [...]Miškų ir ekologijos fakultetasVytauto Didžiojo universitetasŽemės ūkio akademij