Height, diameter and volume based on stump size for Abies religiosa in different regions of Mexico

Abstract

Forest inventory is the primary method for collecting and recording information regarding the volumetric quantification and yield of trees. However, this is difficult when the individual has been cut and only the stump remains, in which case inventory is achieved through regression techniques. The objective of this work was to adjust allometric equations for the estimation of normal diameter (dn), total height (at) and volume (v) using the stump diameter (dt) for Abies religiosa in different regions of Mexico. A total of 2,599 data points from 20 forest management units were used to analyze the variables and their respective predictions through eight allometric equations, which were evaluated with different statistical criteria. The adjusted coefficient of determination (R²_adj) explained 91 % of the normal diameter, together with the root mean square error (RMSE) of less than 4.75 cm with respect to the allometric equation (3). Another of the best options to estimate the total height is the Schumacher exponential (4) and the allometric (6) with values of R²_adj of approximately 50 %, accompanied by RMSE less than 5.03 m. However, for the volume of the forest, Schumacher’s equation was considered pertinent since it has a RMSE ranging from 0.00001 to 0.0026 m³ with R²_adj that explains more than 74 % of the variation of the data observed in each UMAFOR. These regressions may be useful for the restoration of trees after an unplanned or unexpected felling event, as the results are statistically reliable.