Quality of beech trees from regeneration fellings of Bilogora region

Research was carried out on the quality of beech trees and the share of timber assortments from regeneration fellings of beech stands in the Bjelovarska Bilogora management unit. Stem cleanliness and percentage of timber assortments were investigated, depending on the type of felling and the diameter of breast height. Research results show a wide range of stem cleanliness, which is not directly related to the diameter of breast height or type of felling. The greatest average stem cleanliness noticed is 13 m in preparatory felling, while values in seeding and final felling are 10 m and 11 m. The interdependence between the percentage of technical roundwood in processed tree volume and the diameter of breast height is determined. The share of technical roundwood, which is regressed by parabola, increases with the increasing of tree thickness in all types of fellings. The greatest value is in diameter 47.5 cm class (67.4 % preparatory felling, 68.5 % seeding felling and 67.7 % final felling), but the share of technical roundwood decreases onwards. The percentage of technical roundwood in the thinnest trees ranges from 30.2 % to 34.3 %. In all diameter classes, the values of each type of felling slightly vary, so the differences in the middle classes are in the range of 2 %, vvhile in the edge classes range from 4 % to 9 %. The share of cordwood ranges by the same analogy. The shares of particular timber assortments depend on tree thickness and type of felling. The characteristics of preparatory felling are little share of high-yield products (veneer logs and logs for rotary cutting) and a considerable share of high-quality sawlogs. Logs for rotary cutting are dominant in seeding felling, but the share of veneer logs and sawlogs of first class quality is greater than in the preparatory felling. In the final felling, there are considerable percentages of veneer logs, logs for rotary cutting as well as sawlogs of third class quality.