Allometric height-diameter equations for Pinus pseudostrobus Lindl

Silvicultural practices used for forest management in the Indigenous Community of Nuevo San Juan Parangaricutiro (CINSJP for its initials in Spanish), Michoacan, Mexico, are important for the sustainability of its woodlands. For this purpose, techniques that provide reliable and current quantitative estimates are required. The aim was to fit an equation that describes the allometric relationship between total height and normal diameter (Th-nd) of Pinus pseudostrobus in the CINJSP forests. Data were obtained from P. pseudostrobus stands that have been managed with the Silvicultural Development Method (SDM) at different stages according to the current forest management program. The research area is between 2,200 and 2 500 masl, has a temperate type C (w2) climate, and is located at southwest of the Purhepecha Plateau within the Trans-Mexican Volcanic Belt region. The sample size consisted of 169 total height-normal diameter (Th-nd) data pairs. Ten allometric models to evaluate the goodness of fit were tested, choosing three models based on the lowest values of the sum of square errors of prediction (SSE) and the root mean squared error (RMSE), the highest adjusted coefficients of determination and the significance of their parameters. The deviations of the models were smaller than 0.01 m. The three-parameter equation Th - K + 38.06004/1+6.033101exp(0.066439dn), proved to be statistically more stable than the rest, and it also shows deviations of less than one meter per tree and less than 1% for the entire population.