Local-global and fixed-random parameters to model dominant height growthof Pinus pseudostrobus Lindley

Abstract

Introduction: Dominant height and site index (SI) models consider average parameters for asample or population. The dummy variable (DV) modeling approach generates global and localparameters, while mixed-effects models (MEM) generate fixed and random ones for each tree orplot. Objective: To fit and compare dynamic dominant height equations with the DV and MEMapproaches for Pinus pseudostrobus Lindley in commercial forest plantations in Nuevo San JuanParangaricutiro, Michoacan, Mexico. Materials and methods: Three algebraic difference approach (ADA) equations and onegeneralized algebraic difference approach (GADA) equation, based on the Chapman-Richardsmodel, were fitted with the SI parameter associated as local or random for each tree. Thedatabase used considered stem analysis of 41 trees. Results and discussion: The accuracy of the fitted equations with DV and MEM was similar,according to the fitting statistics and the trajectories of the SI curves at the base age of 20 years.In the ADA equations, the polymorphic curve showed greater statistical efficiency with bothapproaches when the growth rate parameter depended on the SI. However, the GADA equationgenerated curves that better described the growth pattern; the highest accuracy was obtained withthe DV approach. Conclusions: The use of the GADA equation with DV is an accurate tool for classifying theproductivity of commercial forest plantations, which will allow forest management planningbased on site quality.