Volume equation as basis of community forest management in Anapu, Pará State, Brazil

The community forest management in settlement areas, in Pará, needs tools that provide reliable information about wood potential in the area, as volume equations. Five volumetric models of simple entrance and five of double entrance were adjusted to estimate the wood volume of standing trees in the Project of sustainable development Virola-Jatobá in Anapu, Pará State, Brazil. The trees were cubed using Smalian method. The diameter at 1.3 m above soil level was measured in 172 individuals from 25 species with commercial interest by the community. The diameters ranged from 60 to 120 cm and commercial height varied from 5.24 m to 35 m. The statistic criteria used to select the best volume model of simple or double entrance was adjusted coefficient of determination (R2aj), standard error of estimate (Sxyr), coefficient of variation (CV), average deviation percentage (ADP) and graphic residual analysis. Chi-square test was used to validate the best models. Husch model presented the best estimative of wood volume in standing trees in the studied area, through the equation logv = 0,7974 + 4,4294logd. This equation does not use the commercial height variable, so it field inventory cost less and avoid mistakes from the estimation of this variable