Volume equations for young stands of Pinus taeda L. on the Santa Catarina Plateau

Abstract

The objective of this study was to adjust linear and non-linear models to estimate the wood volume in young stands of Pinus taeda, filling the information gap for the first years of species' stands. The data analyzed derive from selective thinning in a 5-year-old experimental stand of P. taeda, established in the Experimental Forestry Area of the Federal University of Santa Catarina, in the municipality of Curitibanos, SC. The single-input volumetric models of Husch (linear and non-linear) and Kopezky (linear) were tested, using only the Diameter as a variable, and the double-input models of Schumacher-Hall (linear and non-linear) and Spurr (linear), using the Diameter and Total Height variables. All models were adjusted by the ordinary least squares method, using linear and non-linear regression analysis. The best selected single-input and double-input models were applied to an independent database for validation. The double-input models presented better performance than single-input models, but the variation in accuracy and efficiency was not significant. Schumacher-Hall model and the Husch and Kopezky fitted models presented more accurate estimates in relation to the models available in the literature. Therefore, we confirmed the hypothesis that equations for older individuals overestimate the volume of young trees. Then, the models adjusted in the present study provided an accurate estimate of the wood volume coming from young stands and from commercial use of the first thinning.