The evaluation of dependence of the current increment of a pine part of the mixed pine-birch forest stands on their spatial structure

Abstract

To determine the level of dependence of the current growth of the pine part of mixed pine-birch forest stands on their spatial structure the materials of the taxation of trees on 408 plots: taxation parameters, parameters of crowns, as well as coordinates of X and Y were used. The construction of the spatial distribution model on the tree area indicating the diameter of crowns area and the areas of intersection of circles of the competition of the trees of both species was performed with the use of Quantum GIS. To determine the dependence of the current growth of the pine part of the stand on the influence of admixture of birch trees in 44 pines a radial growth was determined, the data were divided into three groups according to the intensity of growth: weak – radial growth for 10 years, 0–10 mm, average – 10–20 mm and intensive – 20 mm and more. The current growth for the selected trees was determined by different methods based on the taxation indices of trees. With Quantum GIS it was possible to de-termine the distance of the birche s trunks closest to the pine. The dependence of the current increment of pine trees on the forest indices and spatial stand structure was determined with the help of the regression analysis. The main criteria for the evaluation of equations served the correlation coefficient, the explanation of the proportion of variance and standard error of the individual factors. As a result of the studies the regressi on equations with correlation coefficients for pine-intensive growth – 0.84, pine average growth – 0.56 for the dominant-term – 0.95 were obtained.