VOLUME ESTIMATION SYSTEM FOR INDIVIDUAL Tectona grandis L. f. TREES THROUGH COMPATIBLE TAPER/VOLUME FUNCTIONS

Abstract

A volume estimation system for individual trees was generated based on a segmented taper function for Tectona grandis plantations established in Campeche, Tabasco and Chiapas. The volume of 144 trees of different ages was estimated; for each, the diameter with bark was measured, as was the height above the stem base from 1 m above the stump to the total height. The statistical adjustment of six segmented taper functions was assessed, and the model of Fang was selected as the best, since it is the most accurate, the one with least bias and provides a correct description of the stem taper. An adjustment was simultaneously made with its respective merchantable volume function based on the mixed effect model technique, whereby the specific variation was controlled at tree level, and the estimation of the parameters and the accuracy of the predictions were improved. The results indicate that the derived volume estimation system consists of equations that accurately describe the stem profile and estimate the merchantable and total volumes, as well as the merchantable length at a minimum diameter and vice versa. The points of change in the dendrometric stem shape are similar to those of other broadleaf tree species. The equivalent of the shape factor from the total volume model was 0.43 in average, which allows estimations that are very close to the observed volumes and is comparatively lower than that estimated total volume for this species in other tropical regions.