Cross-sectional shape evaluation of individual trees in stands

To determine the volume of the growing tree and growing stock of wood, one must know the following parameters: its height, diameter at breast height and shape of the forming barrel. In diameter at breast height cross sectional area is determined and then the barrel volume is calculated. Cross sections of tree trunks are shaped like a circle or an ellipse.However the form of cross sections of trunks varies greatly. Formulas of a circle or an ellipse can give a considerable error at measurement of a tree which cross section has the wrong form. It, in turn, will be reflected in scoping of a tree and a stock of planting. Taking into account the cross-sectional shape of the trunk at breast height can increase the accuracy of determining the volume of individual trees. The article summarizes different methods for determining the cross-sectional area, their effect on the errors and volume of the barrel. The study also examines the conditions of growth influence on the shape of the cross section of a tree. It was found out that the most appropriate method for determining the cross-sectional area is based on the calculation of the area using the formula of the ellipse to the maximum and the minimum diameter, and gives an error of 1.6 to 3.45 %. The error in determining cross-sectional area decreases with increasing altitude at which the measurements are made. The bark has a significant impact on the shape of the cross section. Theinfluence of age, completeness, type of wood, slope exposition on a trunk section form at breast height is revealed, however these researches are not enough to describe all variety of the factors influencing the form of a trunk cross section.