Динаміка продуктивності деревостанів Східного Полісся України

• Date: 2023
• Main Authors: Zhezhkun , A. M., Zhezhkun , I. M., Porohnyach , I. V.
• Format: Article
• Language: Ukrainian
• Published: Ukrainian Research Institute of Forestry and Forest Melioration named after G. M. Vysotsky (URIFFM) 2023
• Subjects: зміна запасу; відпад; приріст; клас бонітету; тип лісу
• Online Access: https://forestry-forestmelioration.org.ua/index.php/journal/article/view/357
• Journal Title: Forestry and Forest Melioration

Introduction Stemwood volume is a reliable indicator of stand productivity. Many researchers studying productivity use the standing growing stock of specific species without considering dead wood. Understanding the dynamics of forest productivity can optimize forest utilization, ascertain the degree of forest regeneration, and predict stand growth and development. The investigation into the productivity dynamics of tree stands in Eastern Polissia, Ukraine, has not been conducted in recent years. Therefore, this scientific study possesses novelty and relevance. Materials and Methods The research was conducted in young and middle-aged stands. The stand productivity was analyzed according to the stem wood – the dominant and most valuable forest product. The total stand productivity consisted of the available growing stock, the stock of dead trees, and the stock of wood removed during improvement felling. The change in forestry and mensuration indicators of the stands was determined in permanent sample plots, which were established according to generally accepted forestry methods. Results The productivity of forests in the region is constantly changing and in recent years has shown a tendency to increase. It depends on the species composition, origin, age, stand density, site class, forest type, and the influence of natural factors (fires, windstorms, snowmelt, pests, and diseases). In managed forest stands, the stand productivity is also influenced by a regeneration method (natural regeneration or planting), cultivation method (classical or plantation), timing, and quality of improvement felling. Reducing the change in the available growing stock of the stands does not take into account the tree mortality rate, which reduces the total productivity. The mortality in terms of the number of trees is greater in younger stands, while in terms of stock, it is higher in older ones. In the stands of mature age, the mortality rates can increase, which is, with other things being equal, the basis for the appointment of final felling. Before carrying out the final felling in the shelterwood system in thinned pine stands with the relative density of stocking of 0.3–0.4, the probability of tree mortality may increase due to the influence of strong winds. The greatest accumulation of growing stock occurs in middle-aged stands. In the 44-year-old stand growing according to the Іb site class and dominated by Scots pine (Pinus sylvestris L.) in the composition, for 5 years there was an increase in the average height (by 1.5 m, or 7%) and the average diameter (by 1.1 cm, or 4.3%). Over the next 5-year period, an increase in average height (by 3.5 m, or 15.3%) and average diameter (by 2.9 cm, or 10.9%) was detected. The increase in the difference in average morphometric indicators by more than two times, compared to the previous accounting period, is explained by the increase in the diameter of thicker pine trees and the mortality of thinner ones. The dynamics of growing stock increment with increasing age of the middle-aged pine forest has an upward trend. Conclusions The productivity of tree stands according to stem wood stock in the region has a tendency to increase. The highest values of the current average periodic growing stock increment were determined in middle-aged stands. Under forest management intensification, dead-tree wood and growing stock increment should be taken into account to determine the total productivity of stands. During the forest inventory, it is necessary to determine the total productivity and use of deadwood in total wood use, the share of wood use taking into account the total stock increment (with deadwood), not just growing stock changes. Determining the stand productivity dynamics for a certain period will ensure the selection and assigning of measures to increase productivity, provided that their biological stability and durability are preserved, and the protective and environment-creating properties of stands are fulfilled. 3 Figs., 2 Tables, 36 Refs.