THE EQUATIONS OF THE RELATION OF THE WEIGHT OF ABSOLUTELY DRY PHYTOMASS FRACTIONS OF ALNUS INCANA (L.) MOENCH TREES WITH THE TAXATION DIAMETER IN THE TAIGA ZONE OF THE ARKHANGELSK REGION

The relationship between the absolutely dry aboveground phytomass of fractions of gray alder (Alnus incana (L.) Moench) trees and a diameter at a height of 1.3 m was researched in tall grass gray alder stands in the Arkhangelsk forestry, which belongs to the North-taiga forest region of the Arkhangelsk region and to the land territory of the Arctic. In the field season of 2020, 4 trial areas were laid, and 5-6 model trees were selected and measured on them, falling on 2- centimeter thick steps. A total of 21 model trees were studied. The weight of freshly cut and absolutely dry phytomass of 4 fractions of trunk wood, trunk bark, branches and foliage was determined from model trees. Based on the collected data, graphically obtained allometric equations of bonds by fractions for each sample area. Allometric equations are chosen for this purpose in both Russian and foreign studies. Based on the fact that the obtained determination coefficients in most cases exceed 0.8 and in two cases are in the range from 0.7 to 0.8, general allometric equations were derived using all model trees. Comparison of the results of the calculation of photometric indicators in t/ha by general equations with the equations obtained separately for each forest stand shows that the general allometric equations mostly underestimate the phytometric indicators. The best calculation results were obtained for wood and trunk bark fractions. These fractions are of the greatest importance when harvesting wood. Based on general equations, for the first time for the Arkhangelsk region, a table has been created that characterizes the wood fractions of gray alder by weight on each of the 2-centimeter steps of thickness from 4 to 16 cm. The equations are practically applicable for predicting the average absolutely dry phytomass of various fractions at various harvesting operations.