Competition Between Pine trees and Necessity of Thinning

Abstract

55-year-old forest crops of 1B bonitet pine were studied on 17 trial areas with continuous tree mapping. Average height and diameter 27.2 m and 20.6 cm, fullness 0.96, density 940–1620 pcs / ha. In the ArcMap–ArcView program, tree feeding polygons were built for the age of 30–40 years (1623 polygons) and for the same trees in 41–55 years with an increase in their area after the fall of trees (596 polygons). The correlation between the feeding area in 30–40 years and the diameter of the tree was r = 0.252±0.023 with an influence strength of 6.4%. In dense areas of crops, the studied correlation decreased to r = 0.19±0.03, and in rare places it significantly increased to r = 0.32±0.03. In dense areas of forest crops from 928 polygons, two samples were formed: from 589 that did not change the area and from 339 with its increase by 23%. The studied correlations were almost equal: for the age of 30–40 years, r = 0.221 and for 41–55 years, r = 0.226. In rare forest crop locations, new polygons increased by 13%, and the difference in correlations was also unreliable. Thus, using an additional feeding area of about 20 years, the trees did not significantly increase the effect of this area on the trunk diameter. The competitive pressure of neighbors was also calculated as the sum of their diameters divided by the feeding area (98 polygons). The strength of the neighbor’s pressure on the central tree was equal to 3.2%, and with such weak competition, there is no need to reduce the density. Therefore, thinning should be moved to the age of 10–15 years, when it is still possible to influence the genetic structure and change the development towards more productive models of cultivation.