Radial variation of anatomical features, physicomechanical properties and chemical constituents and their potential influence on the wood quality of 45-year-old Eucalyptus propinqua

Summary

The potential commercial use of Brazilian-grown Eucalyptus propinqua for furniture and other applications has been largely ignored in favour of native woods. In part, this results from unfamiliarity with the properties of this species, especially in mature trees. To address this gap in our knowledge, we have characterised the wood anatomy, physical and mechanical properties, and chemical constituents in the radial direction of five E. propinqua trees sampled at breast height. The anatomical features follow the typical radial pattern, which includes differences in juvenile wood when compared with mature wood. Basic density peaked in samples formed 17–30 years from the pith before decreasing at ages 38–45 years (a decline reflecting the low extractive content of the sapwood). We did not observe a pattern of radial variation in mechanical properties. Extractive content increased up to 25–30 years of age and then decreased significantly at 38–45 years with values similar to those of the wood from the sample close to the pith, while the holocellulose content presented inverse behaviour. The lignin content did not change radially. We concluded that many features of E. propinqua wood vary radially, as with many other species of the Eucalyptus genus. This variation, however, was not evident in important mechanical properties and was muted in others. The quality of the wood makes it suitable for many applications, especially after some 17 years of age when ‘mature’ wood, indicated by a declining (and non-significant) rate of increase in fibre and vessel length, is first produced.

Keywords:

• wood
• quality
• working properties
• wood properties
• grey gum
• Eucalyptus propinqua

Acknowledgements

The authors thank Sonia Godoy Campião from Seção de Madeira e Produtos Florestais—Instituto Florestal; Regina Maria Buch from Laboratório de Química, Celulose e Energia; and Luis Eduardo Facco from Laboratório de Propriedades Físicas e Processamento da Madeira—Escola Superior de Agricultura Luiz de Queiroz (ESALQ) and Universidade de São Paulo (USP) for laboratory assistance.