MODELS OF DOMINANT HEIGHT GROWTH AND SITE INDEXES FOR Pinus ayacahuite Ehren

Abstract

The development of mathematical models with technical and scientific bases is important in forest management decision-making. The objective of this study was to model dominant height growth of Pinus ayacahuite Ehren to enable productivity projections. Data on stem analysis of 34 P. ayacahuite individuals were used to fit growth models, classic in forest biometry (Schumacher, ChapmanRichards, Levakovic II, Hossfeld IV and Gompertz), as well as the modeling strategies Guide Curve Method, Algebraic Difference Approach (ADA) and Generalized Algebraic Difference Approach (GADA), using non-linear least squares method. A simultaneous fit was used for the ADA and GADA equations and a 40-year base-age. The graphic and numerical results of the models were satisfactory, according to the statistical indicators of goodness of fit. The indicators of fit of Chapman-Richards polymorphic b2 models in guide curve and ADA, polymorphic b1 of Hossfeld IV in ADA and the Hossfeld IV model under the GADA approach were better than the other models. The models selected enabled the construction of families of site index curves. Of these, the Chapman-Richards polymorphic b2 model in ADA had the best prediction capacity. Therefore, its use is recommended for determining the site index and to classify levels of timber productivity of P. ayacahuite stands.