Abstract

GARCIA-CUEVAS, Xavier et al. Equations to predict the normal diameter based on the stump diameter of Abies religiosa (Kunth) Schltdl. et Cham. Rev. mex. de cienc. forestales [online]. 2016, vol.7, n.37, pp.95-103. ISSN 2007-1132.

In forest areas under exploitation, we require the normal diameter (DBH) to estimate the removed volume. The DBH is estimated based on the stump diameter (SD) by regression and a volume equation. With support from an equation that depends on the ND or the SD, the volume (V) is estimated. The aim was to develop predictive equations of the normal diameter depending on the diameter of the stump for Abies religiosa in Tancítaro, Michoacán. 1 083 pairs of data of SD-ND of different diameter categories were taken. For setting PROC MODEL was used and the selection of the best equation was based on the Mean Square Error (MSE), the Root Mean Square Error (RMSE), significance level of estimators (Pr>|t|) and the fitted coefficient of determination (R2adj) and the residual distribution. To verify compliance with the assumptions of regression, Shapiro Wilk test was used and for the prediction, accuracy was estimated bias ($\overline{E}$). The equations obtained are $d=1.11149+0.92267dt,d=0.173763dt{\left(\frac{1.3}{ht}\right)}^{1.048363}$, and d = 1.11149 + 0.92267 (0.92267 dt). Based on the SME = 2.216, 2.093 and 2.216, the R2adj = 0.9938, 0.9942 and 0.9938, the significance of the parameters Pr>|t| = <0.0001, normality test of Shapiro Wilk and its predictive capacity, it follows that the equations are valid for predicting the function of ND-SD. The fitted models indicate a linear trend between DBH and SD.

Keywords : Abies religiosa (Kunth) Schltdl. et Cham.; allometry; management; regression; prediction; volume.

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