Structure of pine stands in the Pridonetsk Steppe of Ukraine

Abstract

An analysis of Scots pine distribution in the forest fund of the study region was carried out and forest-mensurational indexes were determined in the areas under pine stands. The pine stands of three enterprises under study are described according to the following characteristics: forest type, density of stocking and productivity. The taxation structure of pine stands in the conditions of the study region is considered. To study the structure of Pinus sylvestris L. stands, experimental data collected on temporary sample plots in stands of the Prydonetskyi Steppe were used. Processing of experimental data in order to obtain information about the parameters of the distribution series by diameter was performed using applications (MS Excel, STRUK, BUDOVA). The average diameter, coefficient of variability, minimum and maximum reduction numbers, indicators of skewness and kurtosis were calculated, as well as statistical processing of the array of experimental data was performed. An analysis of the distribution of trees by Kraft's classes showed that class 2 prevailed (75.4%), the share of trees of class 3 is 12.3%, class 1 – 2.5%, class 4 – 1.5%, class 5 – 8.3%. The average values of the skewness of the diameter distributions are 0.33; kurtosis – -0.08. The distribution of trees by diameter is characterized mainly by a sharp-topped curve with right-handed asymmetry. The models of diameter variability, the ratio of variability of the share of marketable trunks to the total variability of the stand diameter are calculated, taking into account the minimum and maximum diameters of modal stands. According to the results of the correlation analysis, the closest correlation is found between diameter and the maximum and minimum reduction numbers, slightly less close relationship is revealed between age and diameter and maximum and minimum reduction numbers. According to the results of comparison of the pine stands of the Prydonetskyi Steppe of Ukraine with the data for Polissia, it was found that the latter showed greater variability in diameter, which is primarily due to forest site conditions in the region and the management regime. The calculations of diameter distribution models of pine trunks have shown that the β-distribution is optimal for this object of study. The relationship between the share of marketable trunks and the age of modal pine stands has been revealed. Tables have been developed for the dynamics of commodity structure of modal pine stands, taking into account the distribution of volumes of marketable trunks by diameter classes, consistent with European approaches to evaluation of round timber. To model the dynamics of the commodity structure of pine stands, regional tables of growth of the Prydonetskyi Steppe, tables of distribution of the volume of industrial trunks of pine by classes and subclasses of diameters and structure parameters by diameter are used. The maximum average stock change of commercial timber (3.7 m3·ha-1·year-1) was observed at an age of 60 years. The presented standards of tree distribution by diameter and dynamics of commodity structure of modal pine stands, taking into account the composition of marketable timber by diameter classes, can significantly improve the quality of forestry and the accuracy of determining evaluation indicators of pine stands of the Prydonetskyi Steppe.

Keywords

• pinus sylvestris l.
• modal stands
• kraft’s classes
• diameter distribution
• commodity structure dynamics