Volumetric equation models for a eucalyptus stand in Codó (MA)

Abstract

This work aimed to test and compare some volumetric models widely used in forest management in a eucalyptus stand in Codó (MA). The research was conducted at the Federal Institute of Education, Science and Technology of Maranhão (IFMA), in the municipality of Codó (MA). For the adjustments of the volumetric models, the Smalian, Huber and Newton methods were taken into consideration, and the Smalian method was used for the rigorous cubing, due to its greater ease and speed in taking diameter at the ends of each. log. The data were obtained by the entirely random sampling process, where the rigorous tree cubing was obtained from the sample intensity, calculated in the area through a forest inventory. The equations analyzed were Spurr, Comprehensive, Spurr Ln and Schumacher and Hall and to select the best equation six criteria were used: coefficient of determination; residual standard error; coefficient of variation; ease of application of the equation and graphical analysis of residues. The overall average obtained from tree volumes was 0.0294 m3 with a coefficient of variation (CV%) of 46.67%. The data show that the four equations tested presented satisfactory statistical performances regarding the values ??of R2 (%), ranging from 75.6% to 77.5%. This high performance means that there was a high proportion of the observed variability in tree volume. As for the selection, it was chosen as the best equation of Schumacher and Hall, due to its simplicity and ease in its application.