ECUACIONES ADITIVAS PARA ESTIMAR COMPONENTES DE VOLUMEN PARA Pinus teocote Schl. DE DURANGO, MÉXICO

Abstract

The quantification of volume components and total volume with robust equations is a key component to understand the main products and services derived from trees and forests. The objective of this research was to estímate coefficients with the least variance in additive equations to estímate volume components (total abovegrot.nd, bale, bark, stump, and branches) for Pinus teocote Schl. from Durango, Mexico. Data was collected during harvesting operations of Ejido Vencedores, municipality of San Dimas, Durango and measuerements consisted on stem and bark profiles. Branches were collected from a sample of 45 trees and measured in volume by the volume displacement technique, branches were also piled and pile volume measured in the field. In total 196 trees were used to estímate volume equation coefficients of: a) the combined variabíe equation of Spurr (1952) and b) stepwise regression. Four techniques of parameter estimation were tested: 1) conventional simple linear regression, 2) weighted simple linear regression, 3) seemingly unrelated linear regression, and 4) weighted seemingly linear regression. The results showed that the coefficients estimators with the least variance were developed in weighted seemingly unrelated regression and the conventional statistical parameters did not change. Therefore, it is recommended to employ the comprensible equation (best model derived from stepwise regression) deveioped in weighted seemingly unrelated linear regression for the species P. teocote of Durango, Mexico.