Evaluation of the Wood Quality of Young Cryptomeria japonica Clones

Abstract

One hundred and fourteen 10-year-old standing C. japonica 38 clones were examined by a non-destructive method to ascertain the possibility of evaluating the wood quality of standing trees with breast-height diameters of less than 10 cm. The results suggested that basic density could be estimated based on its significant negative correlation to pilodyn penetration depth (r=-0.81, p<0.01). In terms of the modulus of elasticity, there was a significant positive correlation between the stress wave propagation velocity and the dynamic modulus of elasticity of logs (r=0.82, p<0.01), suggesting that the estimation accuracy of the stress wave propagation method is high. Furthermore, the accuracy of measurement of stress wave propagation velocity was comparable between measurement interval lengths of 0.5 m and 1.0 m, which is the conventional interval. The lateral impact vibration method was used to estimate moisture content, but there was only a weak positive correlation between moisture content and 1/df (inverse number of the product of stem diameter and fundamental frequency) (r=0.32, p< 0.01); as a result, estimation accuracy was not high. The above findings clarify that, as with standing trees that are at least 20 years old and have breast height diameters of ≧16 cm, density and strength can be estimated for 10 -year-old C. japonica clones with an average breast height diameter of ≦10 cm. Because the measurement method investigated in the present study is non-destructive and can test efficiently a large number of trees, it is suitable for evaluating the wood quality of 10-year-old breeding materials in progeny test plantation. © 2009, The Japan Wood Research Society. All rights reserved.