Andreieva O. Biotic resistance of pine stands of Volyn and Zhytomyr Polissya

The features of the dynamics of climatic parameters affecting the condition and growth of pine stands were revealed. A decrease in precipitation and hydrothermal coefficient of G.T. Selyaninova (HTI) is unfavorable for the growth and condition of trees and favorable for harmful organisms. The features of the distribution of the forest stock of pine stands of individual forestry enterprises by types of forest site conditions, stand composition, age, the relative density of stocking and changes in these parameters during the period between the last forest inventories, which affect the attractiveness of forest plots to harmful insect foci and the risk of fires, were evaluated. The obtained data support the concept of P. Manion regarding the factors of forest decline. A high proportion of pure pine stands and stands over 50 years old are long-term predisposing factors. Anomalous increase in air temperature and reduction of HTI to the level characteristic of the steppe zone are the short-term inciting factors that increase the susceptibility of trees to colonization by bark beetles, which are contributing factors. The obtained results made it possible to develop proposals for forecasting the risks of deterioration of the conditions of pine stands in the region and measures to increase their sustainability. In particular, it is suggested: to adjust the terms of creating pine plantations, removal from the forest or protection harvested wood with insecticides, taking into account the change in the terms of the beginning and end of the growing season; to implement an improved algorithm for determining fire hazard classes; to create mixed stands according to the type of forest site conditions; to carry out timely thinning to maintain the optimal structure of the crowns and sufficient relative stocking density of the stands in order to increase their resistance, in particular to damage by insects and fires; to assess the threat of the formation of foci of foliage browsing insects in pine plantations created at the clear-cuts of sanitary fellings of the last decade and to apply suggested models to predict tree damage by phytophages.