Modelos volumétricos, fatores de forma e equação de afilamento para floresta de terra firme da região do rio aru município de Portel-Pará.

Abstract

The sustainable way of use of the forest resource requires important management tools as accuracy in wood volume measures. Within this context, eight regression models were tested, five single entry and three with double entry aiming the objective to find the best models to estimate the volumes of standing trees, for the ecological conditions for the Aru river region, Portel county, Pará state. A cubed trees of two hundred sixty five of 45 species sampled trees, and diameters varying from 15 to 130 cm were used in order to develop equations for volume. To select best models, statistic like F, r2, Syx, CV and index furnival, were used to compare arithmetic and logarithmic equations, average residual percentage deviation. About the simple entrance models, the logarithmic model Brenac logV = 1.140984 + 1.854200logD - 0,09420 1-D (r2 = 0,957) has shown the best data adjustments, and about the two entrances model, the logarithmic model Schumacher & Hall logV = -0,0571+2,026275*logDAP+0,862432*logH (r2 = 0,983) was the best adjustment. An apart group of 87 trees were used to validate trough χ2 statistic, the estimated volumes by volumetric models that has shown the best adjustments with true volumes obtained by Smalian method. As a complement for the χ2 test, an ANOVA analysis were made, in which the three treatments were the volumes and the Block’s diameters class. Both cases has shown no difference between estimated volume and true volume, demonstrating the viability of the adjusted volumetric models’ application for the studied area. The tree shape was defined as form factor for all the sampled species (ff médio = 0,75). Taper functions were adjusted for Manilkara huberi and Manilkara bidentata subsp. surinamensis. By using the model suggested by Kozak (1960), (d/dap) 2 = 1,0174- 1,0873(h/H) + 0,6534(h/H) 2. The utilization of form factor 0,7 suggested by Heinsdijk, underestimate the volumetric calculation of the tropical florest on the rio aru’s region, what shows the importance of the local volumetric models adjust to make a better accuracy of standing trees volume estimation.