Dynamics of the formation of the structure and the relationship of the main indicators of pine (Pinus sylvestris L.) forest crops in the felling of a berry pine forest in the Middle Urals

The object of the study is industrial forest plantations of pine aged 6-12 years, created on freshly cleared land in the berry pine forest type of the Middle Urals. The aim of the study is to assess the dynamics of changes in the structure and biometric indicators and parameters of tree crowns in industrial forest plantations of Scots pine. The research was conducted in 2018-2024 on a permanent test plot. During field studies, the number of surviving trees was determined: 66.5% of the total number of planted trees survived in 6-year-old crops, 60.0% in 9-year-old crops, and 55.4% in 12-year-old crops. For all surviving trees in the permanent trial plot, the diameter at mid-trunk height, trunk height, crown dimensions along and across the row were measured, and the length of all annual shoots was also measured. The data obtained during field studies, in laboratory conditions, were processed using mathematical statistics methods. A dynamic increase over time in the average taxation parameters of trees and their crowns, a certain decrease in the value of the variation coefficient and the amplitude of rank coefficients were established. Relative stabilization of the structure along the trunk thickness is observed only in 12-year-old pine crops. The structure of the trunk height significantly stabilizes by the age of 12 years of forest plantations, and the leaders and the most lagging trees in height are finally determined. The coefficient of determination between the height of trees and their trunk thickness significantly decreases from 0.653 to 0.428 with increasing age of pine forest plantations. The multiple correlation coefficient between tree height, tree trunk thickness and crown projection area steadily decreases from 0.897 to 0.522 with increasing age of pine forest plantations.