About thinning in the Arkhangelsk region

FBU Northern Research Institute of Forestry, Research department, Arkhangelsk, 163062, Russia

^* Corresponding author: surina_ea@sevniilh-arh.ru

Abstract

An analysis was made of the growth of birch-spruce plantations, passed through three stages of thinning (in 1966, 1974 and 1984) in the Northern district forestry (in the Obozersky forestry) in the Arkhangelsk region. The duration of observations is 54 years at the time of the last count in 2020. The results of past studies by employees of the FBU “SevNIILKh” were taken into account. During the period under review, the forest stand in the control section (without thinning) developed quite dynamically. The birch element of the forest prevailed at all stages of growth and was characterized by the highest productivity (I-II quality class) at the age of 40-50 years. At present, the period of active growth has already passed, the stands are approaching the age of natural ripeness, as evidenced by the decrease in the quality class to IV, the decrease in the average height, and the decrease in stock. Spruce in the second tier and in a depressed state. With the continuation of the decay of the birch element and with an increase in the light regime, the spruce will actively grow. The research data show that in stands that have been thinned, the trees become larger, the yield of large-sized marketable wood is greater than in nonsparse ones. Since the main place in the cost of timber belongs to quality indicators, the economic efficiency of plantations with thinning is obvious. Through thinning, it seems possible to form plantings of optimal composition and density, better growth rates and at the stage of main felling, providing a greater economic effect compared to control