ABSTRACT
This study had the objective of studing the stem shape of Eucalyptus grandis Hill ex Maiden, based on 261 trees, with diameters at breast height (DBH) ranging from 8 cm to 74 cm, originated from Aracruz Celulose S. A. forests, located at Depressão Central and Escudo Sul-Riograndense, in Rio Grande do Sul state, to determine the volume and assortment of wood in two classes: timber (logs with 25 cm of minimum diameter, with bark, and lengths of 5,6; 4,2 and 2,8 m, prioritizing the higher length assortments formation) and industry (stems or portions of stem with diameters between 8 and 25 cm with bark). The fiftieth degree polynomial, having as dependent variable the relative diameters (di/d) and independent variable the relative heights (hi/h) was selected to describe the shape, with data stratification in three diameter classes (DBH): diameter until 20 cm; between 20 and 30 cm and larger than 30 cm, with coefficient of determination higher than 0,97 and standard error of the estimation lower than 6,2 %, allowing to estimate the relative and absolute volume of the assortments through integration of form function. The model adjustment for the trees complex covering all the diameters breadth generated a coefficient of determination equal to 0,98 and a standard error of the estimation equal to 6,54%, also allowing to select the model to describe the shape and assortment prediction.
Key words:
Stem shape; assortment; volume; Eucalyptus grandis