STRUCTURAL FEATURES OF PROVENANCE TRAIL PLANTATIONS OF PINE IN TERMS OF DIAMETER

Abstract

The article analyzes the indicators characterizing modern structure in terms of diameter in provenance trial plantations of Scots pine, created in 1959 by manually planting 2-year-old seedlings using Kolesov's sword at the Stupinskoye Pole training ground in the Voronezh Region, with an area of 26.1 hectares on agricultural land. Based on the data of continuous tree counts on 32 temporary sample plots established in 2018-2020, and representing 18 forest-steppe and 14 steppe ecotypes from the forestries of the European part of the Russian Federation and Ukraine, the diameters of the thinnest, middle and thickest pine trees were determined, as well as rows of their distribution were built for 2 and 4 cm steps of thickness. It was found that distribution of trees in the forest-steppe ecotypes of pine has a unimodal character, typical for a normal distribution, but with insignificant right-hand asymmetry. The distribution of trees of steppe ecotypes is also asymmetric, but bimodal one. In this case, the top of the first right-sided and smaller peak falls on a step of 20 cm thickness, and the top of the second, higher peak falls on the central step of thickness (28 cm), which is associated with the natural cyclic-wave decay of small-sized pine trees of steppe ecotypes growing in conditions of the forest-steppe, where the object of research is located. In pine plantations of forest-steppe ecotypes, 65.3% of the trees are concentrated in the five central steps of thickness, and in the steppe ecotype - only 52.0% of their total number