Wood Quality of Sugi (Cryptomeria japonica)

Cultivars as Structural Members

Abstract

The change in social needs now imposes the following task for “wood quality” on forestry researchers: the wood quality should be reformed so as to satisfy various current demands and coming timber utilisation. The purpose of the study was to seek for the wood quality indices which contribute closely to the production forestry and the timber utilisation.
The experimental results obtained were summarised as follows:
(1) There are so many sugi (Cryptomeria) cultivars and their wood quality was so divrse. Consequently, the effect of cultivar species on wood quality can not be neglected.
(2) The basic density, obtained from green volume and ovendry weight, and the latewood tracheid length had lower coefficients of variation within each cultivar than those among different cultivars.
(3) The growth ring width is not valid as a wood quality index.
(4) The latewood tracheid length, which can be easily introduced into the forest industry and timber industry, is expected to be an effective wood quality index of sugi-cultivars.
(5) It is questionable to introduce a stress grading machine into the sawn timber grading of a mixture of cultivars.