Quantification of the form factor by volume calculation methods in Pinus taeda L

The present work aims to compare 5 cubing methods, Hohenadl 5 and 10, Newton, Smalian and Huber in comparison with the xylometer to determine the shape factor of trees at the ages of 9, 13 and 20, in addition to the determination of the form factor of the first log into two different components. The study was carried out in a forest company in the municipality of Ponte Alta do Norte / SC, with a database consisting of about 30 trees each of different ages that were subjected to cubing by the different methods tested. The form factor for each cubed tree was determined and was obtained by comparing the strict volume and the cylinder volume at 1.30 m from the cubed trees. To determine the form factor of the 1st point, Kozak's affiliation models and the product were defined considering the lengths of 2.50 and 3.05 meters, which were calculated from the adjusted R-2 statistic Syx%; the Analysis of Variance (ANOVA) to compare form factors at different ages was also performed. Through ANOVA, differences between the form factors of the calculation methods were detected at ages 9 and 13, but not at age 20; and through Dunnett test, Hohenadl 5 and Newton methods with media statistics in relation to the Xylometer; but at age 13 it was different from the Xylometer. Regarding age 20, although ANOVA does not show differences, Smalian shows the smallest deviation (%) with -3.56% and the others had a overestimated higher tendency. To determine the shape factor of the trees or the Kozak model, it performed better in relation to the statistical criteria, yielding an adjusted R-2 of 0.8293 and standard error of estimate of 9.49%. The first log form factor shows an average of 0.8136 and 0.8294 in lengths of 3.05 and 2.5 meters respectively. The use of the volume of the first log of the purchased ones, the form factor and the volumetric adjustment of the Kozak model are satisfactory, as they do not differ statistically. For age 9, the form factors of the Hohenadl 5 and Newton methods are indicated, and Smalian for age 20 for satisfactory results close to the Xylometer values.