Scots pine thinning experiments in southern moravia - straznice I and straznice III

The effects of thinning on the growth and yield of Scots pine (Pinus sylvestris L.) were investigated at two long-time experiments in southern Moravia (Czech Republic). The experimental sites are situated at an altitude of 207 m (Straznice I) and 190 m (Straznice III) a. s. l., a subsoil material is sand, soil type is classied as haplic arenic podzol, ecosite was determined as nutrient-poor Pine - Oak (Pineto - Quercetum oligotrophicum arenosum). The experiments were established in 1962 at the age of 33 (Straznice I) and 38 (Straznice III) years. Each experiment included three plots with treatments: control, thinning from above and thinning from below. Diameters and heights of trees were measured in ve-year periods. The latest measurement was done in 2008. In thinned plots, natural mortality was considerably lower compared with unthinned plots. The diameter of mean stem clearly increased in thinned plots. However, diameter of dominant trees (100 thickest trees per hectare) was not affected by thinning. The development of slenderness quotient was similar in all treatments. We found no clear relationship between treatments and basal area, stand volume or total volume production. The unclear effect of thinning was probably related to late age in which the thinning started.