Evaluation and validation of taper functions for Mimosa scabrella Bentham in stands in the Curitiba Metropolitan Region.

Abstract

This study was accomplished with the objectives: to evaluate the acuracy of non segmented polynomial models to estimate diameters and volumes along the stem of Mimosa scabrella. The data base was composed by 174 trees of Mymosa scabrella, where 121 trees were cubed by the method of Hohenadl with ten sections and 53 trees by the method of water displacement (xilometer). All sample trees came from the Metropolitan Area of Curitiba/Paraná. The tested models were those from Schöepfer (1966), Hradetzky (1976) and Kozak, Munro and Smith (1969). The acuracy of the tested models for the estimates was evaluated through: graphic analysis of residuals, adjusted R2, standard error of estimate in percentage (Syx%) and graphic analysis of average profiles, just used to verify if the fittings were satisfactory in a general way. The volumes of the 53 xilometered trees were then estimated through the equation of better performance, as by age class, as for the total of trees. The estimated volumes of these 53 trees were compared with their respective observed volumes through the statistic. After the analysis of results it was concluded that the model from Hradetzky (1976) was the best, as for estimating diameters, as for estimating volumes, in almost all age classes. It was also the best for the total data set. The validation test proved that taper equations of best performance for diameter estimation along the stem were also the best for volume estimation. Therefore they can be used to do the assortment.