Equations and Form Factor by Species Increase the Precision and Accuracy for Estimating Tree Volume in the Amazon

The adjustment of volumetric equations, as well as the form factor by species, represents valuable tools for conducting sustainable management plans. So the goal of this study was to evaluate the employment of volumetric equations and form factor to estimate the wood volume of native species from the Amazon biome. Two hundred nineteen trees, distributed in eleven species, were cut down and dragged to the storage patio for scaling by the Smalian method. Eight mathematical models were tested with simple and double entries, whose independent variables were their DBH and diameter at commercial height. The dependent variables were the commercial volume outsidebark, by species and for the mix of species. The statistics were analyzed alongside a graph for the observed and estimated volumes, and a graph for the residual dispersion and the average residual. The form factor was calculated both by species and for the mix of species. In general, the model that resulted in the best estimative was the Schumacher-Hall method. The same can be observed for the mix of species. The average form factor was 0.7978, differing from the established by the legislation, which is equal to 0.7.