The assessment of growth of spruce undergrowth in uneven-aged bilberry birch forests of Vologda region

The purpose of the study was to investigate the vitality of spruce undergrowth beneath the canopy of uneven-aged birch forests of bilberry types of conditions of growth site to justify the optimum mode of care for undergrowth of spruce young growth to restore spruce formations. The main objec-tive of research was in the assessment of vital condition of spruce undergrowth in the course of age development and formation of a birch forest stand. The study of natural regen-eration in softwood plantations was carried out in Syamzhensky area of the Vologda Region in 2016-2017. The object of the research was the growth of spruce in uneven-aged birch forests of bilberry type in different conditions of the place of growth. The object of the study was adolescents in spruce birch forests of different types of conditions of the site of growth. According to the results of the conducted research it can be noted that natural regeneration of spruce under the canopy of birch forests in the middle taiga subzone proceeds well. The state of the population of spruce under the canopy of birch forests is in many respects associated with the stages of age development of the main canopy. With increasing age of birch stands, the density of spruce undergrowth is reduced on average by 11 %, and its age increases on average by 23 %. Average category of viable spruce undergrowth is reduced from 4.86 to 3.43; annual growth in height is reduced 2.1 times and much inferior to the growth of side shoots (average 17.4 %). The crown becomes umbellate and short and devel-ops asymmetrically. In such conditions environmental factor from the crown of trees of all size categories is lower than unit. To speed up the change of the North taiga birch forests by spruce, it is advisable from economic perspective to carry out thinning birch layer to be implemented through timely and selective cutting intensity of 45-52 %.