Summary
The derivation of a value termed the R-ratio (the change in external wood volume during shrinkage or swelling per change in the weight of the associated volume of water) and its possible use as an indicator of dimensional stability (Chafe 1986, 1987), has led to its consideration as a potential wood quality index for the eucalypts. An analysis of R with respect to mechanical strength, durability, volumetric shrinkage, collapse and density in 38 species of eucalypts has shown a high degree of correlation and suggests that R could provide a single overall indication of timber quality.
While density was more highly correlated with strength and durability than R, the R-ratio was more highly correlated with shrinkage. Also, when predictor criteria (strength, durability, shrinkage, density) were mutually adjusted in multiple regression analysis, R remained significantly correlated with each. When density was similarly regressed against shrinkage, durability and strength, the relationship was not significant for shrinkage.
The observed high correlation between durability and density suggests that mass of wood substance is an important criterion in defining resistance to wood decay.
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The author wishes to thank Dr. W. E. Hillis, Mr. W. G. Keating, Mr. J. Ilic and Mr. E. P. Lhuede for kindly assigning wood quality rankings to the 38 species of Eucalyptus discussed herein
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Chafe, S.C. Towards defining a wood quality index for the eucalypts: the R-ratio. Wood Sci.Technol. 21, 131–138 (1987). https://doi.org/10.1007/BF00376193
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DOI: https://doi.org/10.1007/BF00376193