Efeito de variáveis de copa em funções de afilamento

Abstract

This study aimed to evaluate the contribution of crown variables and morphometric indices in the estimation of tapering. The study adopted individuals of Xylopia brasiliensis, located in the Forest Reserve of Universidade Federal de Lavras (UFLA), a forest fragment of 5.8 ha. A non-destructive cubing was performed involving 77 trees of the species in seven classes of diameter. The tested models were the Shöepfer, Hradetzky and Kozak, traditional models. The stepwise procedure was used to generate a new model with the inclusion of crown variables, named modified Hradetzky. The results show that the modified Hradetzky model was similar to the other models with R²aj = 83.88%, Syx = 1.96 cm, Syx (%) = 54.75 and AIC = -2.176,38. The superiority of the Schöepfer, Hradetzky, modified Hradetzky models was proven by the lowest B, MD, SQRR and RP values. In addition, through the VIF, the use of the modified Hradetzky and Hradeztky models is recommended, since the both resulted in VIF values below 5 for the independent variables, therefore, they were not influenced by multicollinearity. In fact, was verified through the graph of standardized residues, that this last model presented little contribution in the estimates due the great similarity to the original Hradetzky. In this sense, the adoption of crown variables in tapering functions did not significantly influence the estimates. However, its application includes a biological and explanatory factor to the profile of the trees.