Effects of physicochemical characteristics on natural durability of eucalypts woods to wood-decaying fungi

Abstract

This study aimed to relate the biological resistance of seven eucalypt woods to wood-decaying fungi with physicochemical characteristics of wood. Two 12-year-old trees per species were randomly sampled, removing disks at 0 (base), diameter to breast height - DBH, 25, 50, 75, and 100% of the commercial height to determine the wood specific gravity. One basal log of 2.20 m of each wooden species was obtained for chemical analysis and biological tests with brown and white rot fungi (Gleophyllum trabeum, Rhodonia placenta, and Trametes versicolor). For these tests, wood samples were taken in two positions in the radial direction of the trunk in the pith-bark direction (median heartwood and transition region; containing heartwood and sapwood), and the relation between wood natural resistance and physicochemical characteristics was established. Wood specific gravity ranged of 0.51 g cm⁻³ to 0.73 g cm⁻³, total lignin of 27.34–32.18%, and holocellulose of 53.39–66.18, not being influenced by pith-bark direction. The extractive and ash contents were affected by the pith-bark direction, in which, in general, the transition region exhibited the highest values contents. The extractive showed a negative relation (−0.67) regarding the loss of mass caused by the fungus Rhodonia placenta. For the holocellulose content, it showed positive relations (0.61; 0.54) to the degradation by Rhodonia placenta and Gleophyllum trabeum, respectively. Independently of the analyzed wood and tested fungus, the median heartwood region was more resistant to wood decay fungi than the transition region.

Keywords:

• Biodeterioration
• natural durability
• pith-bark direction

Acknowledgements

We thank the Foundation for Supporting Research and Innovation of Espírito Santo—FAPES, for the Doctorate Science scholarship to the first author, and to the Florestal Cellulose Nipo Brasileira (CENIBRA S.A.) Company, Brazil, for making the research material available. In addition, to the National Council for Scientific and Technological Development (CNPq) (Proc. 402710/2016-9 and 304721/2018-2).

Authors contributions

The article was written through the contributions of all authors and all of them have approved the final version of the article. P.N.M.N. and R.N.A. carried out the sampling, physicochemical characterization, biological test, and analyzed the preliminary results. P.N.M.N., J.B.P., and F.G.G. proposed experimental solutions, validated the initial objectives of the project, and wrote the original draft. Y.M.L. and N.P.C.M.C. actively participated in the writing of the original draft. J.B.P., F.G.G., and Y.M.L. helped for reviewing, editing, and correcting both spelling and grammar errors.

Disclosure statement

No potential conflict of interest was reported by the author(s).