Estimates of production and properties of eucalyptus wood in Agroforestry Systems

Eucalyptus wood. produced in Agroforestry Systems (AFS) can be used for various purposes such as firewood, fence posts, lumber and charcoal. When it is used for energy purposes, mainly in the form of firewood, it is obtained by thinning and presents smaller diameters. The aim of this work was to estimate the volumetric production and determine the properties of eucalyptus wood from different AFSs for energy purposes. Three AFSs with tree spacing of 9 x 1 m (System 1), of 8 x 3 m (System 2), and of 12 x 3 m (System 3) were evaluated. In each System, we selected three sample trees per DBH class for individual volume determination, basic density, dry wood biomass, carbon content, and higher heating value (HHV) of wood. System 1 presented trees with larger height and the System 3 with larger diameter. There was no significant difference in carbon content among the Systems studied, with an average value of 52.2%. The basic density ranged from 0.40 to 0.43 g cm(-3), with the highest values found in Systems 2 and 3. The PCS ranged from 4576 to 4631 kcal kg(-1), with the highest value for the System 1. The first System yielded higher HHV and lower density compared to other Systems. The highest estimates of Mean Annual Increment (43.01 m(3) ha(-1) yr(-1)), dry wood biomass (17.53 t ha(-1) yr(-1)), carbon (9.16 t ha(-1) yr(-1)) and available energy (69.82 GWh ha(-1) yr(-1)) were obtained in System 1, due to greater number of trees per hectare when compared to the other Systems. We,conclude that the Agroforestry Systems evaluated show potential production of dry wood biomass for energy purposes, with better values, for the System 1 that has a higher number of trees per hectare.