TAPER EQUATIONS FOR PINUS-TAEDA PLANTATIONS IN SOUTHERN BRAZIL

Non-linear regression was used to fit taper functions with data from P inus taeda plantations in Southern Brazil. Five models were evaluated: Kozak et al. (1969); a fifth-degree polynomial; Max and Burkhart (197 6); Parresol et al. (1987); and Clark et al. (1991). Diameter predicti on at 12 points along the stem was made to verify the accuracy and pre cision of these models. Furthermore, their ability to predict total an d merchantable (7 cm and 25 cm top diameter) volumes was evaluated. Mo st of the statistics indicated that the segmented form-class model of Clark et al. (1991) was the best for estimating diameters along the st em and for predicting merchantable or total volume. However, the stati stics also indicate regularity and good performance from the Max and B urkhart (1976); Parresol et al. (1987) and fifth-degree polynomial mod els.