Relationships between longitudinal growth strain and some wood properties in Eucalyptus nitens

Summary

The relationships between longitudinal growth strain and wood properties of Eucalyptus nitens were investigated. Sixty-three 10-y-old trees were selected for this study. Longitudinal growth strain, green density, green moisture content, basic density, radial shrinkage, outerwood and corewood densities, volumetric shrinkage and dynamic modulus of elasticity (MOE) at 12% moisture content and length-weighted fibre length were determined. Amongst all the studied wood properties, only shrinkage-related properties were found to have some association with the mean growth strain in trees. The mean growth strain was moderately but significantly related to the volumetric shrinkage of the outerwood, but not to the shrinkage of the corewood. However, the volumetric shrinkage differential (difference between outerwood and corewood shrinkage) was strongly related to the growth strain (r = 0.70), suggesting that the growth stress gradient might be related to variations in shrinkage properties within the stem. The wood of trees with the lowest growth strains had statistically significantly lower volumetric shrinkage, lower outerwood MOE and less collapse than wood of trees with the highest growth strains. The results suggest that E. nitens trees with low strains could exhibit a lower degree of drying defects such as collapse and checking during processing.

Keywords:

• forest plantations
• wood properties
• growth stress
• strain
• wood density
• modulus of elasticity
• fibre quality
• drying
• shrinkage
• wood defects
• Eucalyptus nitens