VOLUME AND TAPER EQUATIONS FOR COMMERCIAL STEMS OF NOTHOFAGUS OBLIQUA AND N. ALPINA

Abstract

Stand timber volume in standing trees is essential information when making management decisions. The increasing need to optimize the potential capacity from forests, ensuring their conservation requires the quantification of the different possible wood products. The aim of this research was to adjust taper models to determine volumes of different timber products of Nothofagus alpina and N. obliqua. Trees of N. alpina and N. obliqua were randomly selected in harvesting areas and outside them in the study area (National Reserve of Lanin National Park, Argentina). Trees were felled and cut into long tradable, and the following variables were measured in each one: diameter at breast height, total height, diameter with bark, and for each section, the height from the ground. Five models to describe the stem were chosen and nonlinear regression process was made for adjustments. We obtained the volume model through the integration of the stem profile function and the rotation in the space thereof, through solid of revolution. Bennet and Swindel model was chosen to estimate the stem profile of N. alpina and N. obliqua, where similar parameters between the two species were observed, but given the differences produced at the top of the stem of larger trees is not recommended the use of a common model. With this is possible to estimate volume at different heights and for different commercial diameters. Finally, a model to predict the height at which a N. alpina or N. obliqua tree reaches a certain diameter was obtained.