Residual biomass in Eucalyptus globulus plantations according to stand quality

Abstract

Residue from Eucalyptus globulus plantations is an important source of bioenergy for use in power generation plants. In this work, a set of equations was developed to calculate the amount of residual biomass in Eucalyptus globulus plantations depending on their productivity. The volume of wood underbark was obtained from 321 stands. The stands were divided into 8 categories depending on their productivity (underbark volume of stem wood per hectare and year). For each component of the residues (leaves, branches and bark), Biomass Expansion Factors (BEFs) were determined using eight plots of different productivities to enable stem volume to predict residual biomass. The bark was the component with the greatest weight in the residue. Our results revealed significant differences (p < 0.01) between BEFs and productivity. The maximum difference was 0.288 Mg m-3 and 0.160 Mg m-3 between plots categories 8 (lowest productivity) and 1 (highest productivity), respectively. The equations for estimating the amount of residual biomass only depended on stand productivity. At 15 years of age, it was estimated that 75 Mg ha-1 and 39 Mg ha-1 of residue wood was produced for stand categories 1 and 8, respectively. Finally, predicted residual biomass was compared with that measured in the plots and were slightly lower than those measured in the plots. Relative errors ranged between 1% and 11% at 15 years of age.