Selection of Models for Above-Ground Biomass in a Eucalyptus urograndis Stand

The quantification of biomass is an important tool that helps the forest manager to define the course of the enterprise and the best management techniques. In view of this situation, the objective of the present study was to perform the modeling of above - ground biomass in the different components in Eucalyptus urograndis stands at 4.5 years of age. The stand is located in the south of Brazil, municipality of São Gabriel. Four plots of 577.5 m² were installed and all DBH and heights of 20% of the trees were measured. Four diameter classes were defined, with 3 trees being felled in each of them. All the biomass was weighed in leaves, branches, bark and wood and through samples the moisture content in each component was determined. The modeling showed reliability of 96% for wood estimation and biomass total. The total biomass was 65 Mg ha-1, of these, 72% of wood. The modeling with stepwise procedure presented good distribution of the residues. Through the easily obtained variables such as DBH and height it is possible to determine the volume of biomass accurately.