The presence of heartwood influences the use of wood in different ways (Hillis, 1987). The conceptual bases that allowed the precise definition and general physiological aspects involved in heartwood and sapwood formation were... more
The presence of heartwood influences the use of wood in different ways (Hillis, 1987). The conceptual bases that allowed the precise definition and general physiological aspects involved in heartwood and sapwood formation were consolidated for some time, but some current techniques such as X-ray scans, infrared and gamma rays can be used for more detailed quantification and characterization of heartwood inside the main stem (Gominho, 2003). In this study we used the non-destructive method of gamma radiation attenuation to determine the basic and apparent density at 12% moisture content of wood portions (heartwood and sapwood) of mature trees of four forest species (Eucalyptus grandis Hill ex. Maiden - 18 years old, Eucalyptus saligna - 60 years old, Eucalyptus tereticornis - 35 years old and Corymbia citriodora - 28 years old). Six discs were sampled at breast height (DHB) of each species and the heartwood and sapwood were delimited by macroscopic analysis of the vessels (heartwood characterized by the presence of tyloses in the vessels, and sapwood, by the absence thereof) in each sample. The apparent density values ranged from 672 to 933 kg/m³ in the heartwood wood and 749 to 899 kg/m³ in the sapwood wood. The averages of apparent density did not differ significantly between the wood fractions. Despite the different ages of the plantations, the highest values of apparent density of wood, both in the heartwood and in the sapwood fraction were observed in Corymbia citriodora species.
