SITE INDEX CURVES BASED ON MIXED MODELS FOR TEAK (Tectona grandis L. F.) PLANTATIONS IN THE VENEZUELAN PLAINS

Site index curves serve to classify lands in function of their productive capacity for a forest species. In this study, linear and non-linear models were used to develop site index curves for teak (Tectona grandis L. F.) in the western plains of Venezuela using data from permanent and temporary plots that cover more than 30 years of measurement. The Schumacher model, in its linear and non-linear forms, was fit using variants of fixed and mixed effects. The analysis of the results showed better fit of the non-linear mixed models than of the other models in terms of bias and precision, suggesting the convenience of using models that consider repeated measurements in the same plot. The site index curves generated show the dominant height growth variability of this species in Venezuela in the areas that are appropriate for its establishment under traditional management.