Analysis of different adjustment forms of taper functions

The aim of this research was to evaluate different adjustments of taper functions for the estimates of the variables diameter, height and volume using the coefficients obtained from the adjustment obtained on the original model and the expression of h(i) and d(i) variables. Evaluated were the taper models of Baldwin, Demaerschalk, Kozak e Ormerod of Eucalyptus urophylla x Eucalyptus grandis stem. The estimates of diameter and height obtained from original model (relation (di/dap)) were compared with the estimates obtained from the expressions of d(i) and h(i) rearranged on the original model. The estimate of volume was compared by integrating of the original model and the diameter expression. The choice of the best model and the different ways of adjust were realized by graphical analysis of errors, determination coefficient (R-2), estimated standard error (Syx(%)), bias (V), average of the differences (MD) and standard deviation of the differences (DPD). The Demaerschalk model was the most accurate for the three variables for the different ways of adjustment. Considering the estimate of diameter and height, the adjustment equations for diameter and height variables have proved more accurate while the estimate of volume was more accurate with the integration of the expressions of diameter.