DO THE DIAMETERS OF THE NEIGHBOURING TREES CORRELATE?

Abstract

Introduction. Assigning trees to felling is based on the spatial arrangement of trees. The main visual parameter for a forester is the minimum distance to the nearest species, which is recommended to be increased in order to reduce competition, it preconditions the relevance of studying this issue. In the study of spatial interaction between trees in the cenosis we use a method of the "neighbor". The goal of the study is to evaluate the impact of neighboring trees in pine plantations on the size of each other depending on the distance between them. Material and methods. We made continuous mapping of trees on the area of 2.2 hectares in the 184-year-old plantation of pine trees of the first class quality, 0.93 completeness, and created a map using the ArcGIS application. Correlations in the pairs of neighboring trees were calculated after ranking their diameters, i.e. a tree with a large diameter was placed on the first place, and a tree with a small diameter - on the second place. Totally, 479 distances between neighboring trees were accounted, which varied from 84 to 796 cm, averaging 332±6 cm. The data were processed using standard statistical procedures. Results and discussion. The study has shown that the distance between neighboring individuals in dendrites makes virtually no effect on the sum of the squares of the cross sections of their trunks, defining only 1.7 % of the variance for this parameter. The overall increase in the diameter of the neighboring trees emerges only when the distance between them is more than 5 m. At the same time, the size of both trees depends, most likely, on another as yet unknown abiotic factor leading to a consistent increase or decrease in their size. The dependence of the diameter of a small tree on a large one at a distance between them from 84 to 450 cm approximates the regression equation, which explains only 29 % of the variance of the indicator. When the distance between the trees is more than 450 cm, their diameters are almost not related to each other. Conclusion. In the 184-year-old pine stand microcenotic effects are very weak. Here, along with competition, we observe a phenomenon that can be called "partnership" of neighboring trees, which is confirmed by a statistically significant correlation of their diameters. The agreed decrease or increase in the diameter of neighboring trees may well be caused by a "place factor", i.e. the presence of favorable or unfavorable places of small size up to 4.5 m in diameter on the territory of the biotope, the nature of which remains unknown.