Influence of thinning on protective pineries biosustainability in Northern Kazakhstan

The article presents the results of thinnings in pineries of the Kazakh uplands in Northern Kazakhstan carried out for an over 70-year period and their influence on biosustainability (on the example of the state national natural park «Burabay»). The research objects are high-density mature pine forests growing in dry forest conditions. The results of research have shown that to the average values of the vital status indicator (VSI), the complex estimated indicator (CEI) and the tree slenderness coefficient (H/D), pine stands in most sections are characterized as «weakened». In forest stands after thinning of strong and very strong intensity of thinning in terms of tree slenderness coefficient (H/D) the pine forests is assessed as healthy. It is proved that the vital status maximum credible indicators of the pine forests and the implementation of forestry practices in them is the tree slenderness coefficient. The largest number of trees (up to 70 % of the total number of trees) with tree slenderness coefficient an H/D value of less than 100 in the pine forest after very high intensity thinning is evaluated. A large number of trees with H/D < 100 in the forests proves a weak competition between trees in the forests and higher resistance to natural and anthropogenic factors are proved. The data obtained show a positive effect of strong thinning on the increase in the radial growth of pine trees. For formation of sustainable pine forests in dry growing conditions in Northern Kazakhstan with thinning one-two steps with 26–35 % of the stock volumes destruction at the age of 25–30 years and 40–50 years, and with subsequent increment felling in them is recommended.