Наукові праці Лісівничої академії наук України (Nov 2023)
Group-shelterwood felling in the pine forest of the Eastern Polissia of Ukraine as an important component of the organization of Close-to-Nature Forestry
Abstract
The article presents the results of group-shelterwood felling in mature pine stands of the Eastern Polissia of Ukraine. The sample plots for group-shelterwood felling were established in 2014-2019. In the first cut of group-shelterwood felling, gaps with a diameter of 0.5, 0.7, 1.0, and 1.5 of the average height of pine stands were formed. The reforestation strip of the stand adjacent to the gaps was 0.5 of their diameter. In the gaps all the trees were removed, and in the reforestation strip – the stand was thinned out to the density of 0.4 - 0.5. The intensity of the first cut of felling in the permanent sample plots was 11-21% of the stock of the pine stands. After felling in the autumn or spring, measures were taken to stimulate natural regeneration by loosening the soil with disk cultivators or laying furrows with plows (mineralization of the soil was 90-100 and 50-60%, respectively). During the inventory, individuals of natural regeneration of tree species were divided into self-sown ones of 1 and 2 years of age, advance growth at the age of 3, 4-8 and 9-15 years. Under condition of satisfactory seeding of the pine trees, in the first year in the gaps regenerated were 20 to 190 thousand pcs ha-1 of self-sowing Scots pine (Pinus sylvestris L.). As the size of the gaps increased, so did the illumination. The largest number of the 1-year-old self-seeding of Scots pine was recorded in the southern and central parts of the gaps. During the first 3-5 years, 13 to 65 thousand pcs ha-1 of advance growth survived, also survived 2-7 thousand pcs ha-1 of self-sowing Scots pine and other species, which provided grounds for carrying out the next cut of the group-shelterwood felling. The most effective were gaps with a diameter of 1.0 and 1.5 of the average height of the stands. During the second cut of group-shelterwood felling, the gaps were expanded by 0.5 of their diameter (19.5-58.5 m) and the stand was thinned in the reforestation strip. The intensity of the second cut of felling was 38-63% of the stock of stands. The existing pine advance growth was preserved and activities were carried out to promote natural regeneration. In the remaining part of the stand with a density of 0.2-0.4 after the hurricane of 2022, the share of windthrown Scots pine trees amounted to 13% of the stock. In the first year after the second cut of the felling, 12 to 72 thousand pcs ha-1 of self-sowing pine were regenerated. After the expansion of the gaps during the second cut of group-shelterwood felling, the illumination in them increased. The highest illumination was observed in the northern and eastern parts of the gaps, where the largest amount of self-sowing pine has been preserved. The amount of pine advance growth after the second cut of felling ranged from 8 to 13 thousand pcs ha-1, which was enough to prescribe the final cut of group-shelterwood felling. In the places of expansion of the gaps the common pedunculate oak (0.1-0.5 thousand pcs·ha-1), silver birch (0.2-0.5 thousand pcs·ha-1) and aspen (0.2-1.9 thousand pcs·ha-1) were also regenerated, and the conditions for the formation of stands of mixed composition of natural origin were created. In the process of conducting group-shelterwood felling, natural uneven-aged pine stands of mixed composition with a stepped closure of the forest canopy are formed. Group-shelterwood felling is an effective silvicultural close-to-nature measure, which requires expanding their use in the pine forests of the Eastern Polissia of Ukraine.
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