EVALUATION OF WOOD SELECTED BY THINNING IN PINE FORESTS OF THE CONIFEROUS BROAD-LEAVED ZONE

Abstract

Introduction. The available standards to determine growing stocks are referred to young stocks, mature, and overmature stands only. The standards are of low accuracy to plan thinning operations. There are few studies of the form of stems of middle-aged and ripening stands, the studies do not include revealing of clear dependences on the age which provokes the changes of stem forms of certain trees and, diversity of stem forms for the selected and left trees. The goal of the study is to test the availability of existing tables to determine the volume of certain trees by the stock of clear felling in the young, middle-aged and, ripening  pine stands. At that, the differences in the stem form of the  selected and left stands were revealed (low thinning was used). The results of sectional measuring of 945 trees at 9 sampling areas (natural stands – 5, plantations - 4) was the information to analyze. Results. The test of availability of the four the most widely used tables of stem volumes showed there was only one table to evaluate acceptable growing stock of the selected and left parts of stands. Besides, some systematic variation of deviation from true stocks with the increase of the age of stands is observed. Both in the planted and natural stands aged 25 – 70 the progressive change of stem form is observed. Using one and the same ta-ble of volume, it firstly leads to underestimating of growing stock, and then – to overestimating of growing stock. It was revealed the selection of trees by low thinning simultaneously contrib-utes to removal of trees with ill-developed crowns and trees with high values of height-diameter ratio at breast height. By this, stands sustainability to natural disasters is increased. It is recommended to start thinning when stands closure and to finish thinning at the beginning of polestage stand. It will assure formation of sustainable stands with high life opportunity.