COMPATIBLE TAPER AND VOLUME SYSTEM FOR Pinus pseudostrobus Lindl. IN NUEVO SAN JUAN PARANGARICUTIRO, MICHOACAN, MEXICO.

Abstract

The pine forests in the indigenous community of Nuevo San Juan Parangaricutiro, Michoacan, Mexico, are mainly used in sawmills, but there are no accurate cubing tools for standing trees. The objective of this study was to develop three compatible taper and merchantable volume systems for the data obtained using indirect methods (Criterion RD1000? and LaserAce? 3D dendrometers). Indirect and direct measurements were taken from 30 trees. The resulting data showed less than 1 % bias on the diameter when a Criterion RD1000? was used. In order to calculate the volume with classification of products of Pinus pseudostrobus Lindl., 165 trees were indirectly measured. The sample trees represented all the diametrical categories found in the study area. The compatible taper systems were adjusted using a seemingly unrelated regression (SUR); the heteroscedasticity above the total volume was corrected using a power function of the residual variance; and the taper autocorrelation was fitted with a CAR (2) autoregressive model. The system proposed by Fang et al. (2000) was the most accurate: it accounts for 98.7-98.8 % of taper and merchantable volume variability. Therefore, using this method to describe the stem profile and to estimate the volume with classification of products for P. pseudostrobus in the region is recommended.