Polynomial models to describe the trunk shape of Pinus taeda l.

Abstract

Taper functions allow us to estimate diameters and volumes along the trees trunk. These functions are used to determine wood assortments from forest stands. In this sense, the present study aimed to evaluate the performance of 2nd, 3rt, 4th and 5th degree polynomial models adjusted for P. taeda trees from Correia Pinto (SC). The trees were cubed from meter to meter and polynomial model adjustments were tested in sections of 1, 2 and 3 m from the position referring to the diameter at breast height. The trees volumes were obtained using the Smalian formula. The 4th and 5th degree polynomials presented similar results regarding the fit and precision criteria. The 2nd degree polynomial achieved the worst result regardless of the distances evaluated between the cubes. In general, the 5th degree polynomial model was the most adequate to describe the tapering of the Pinus taeda trunk. For the volume estimates using the diameters estimated with the use of the 5th degree polynomial, better results were obtained with the sectioning of 2 m. This study presents application potential for other forest species.