Variation of specific gravity and young's modulus in the stems of sugi [Cryptomeria japonica] clones
2006
Kurahara, Y.(National Forest Tree Breeding Center, Juo, Ibaraki (Japan)) | Kato, K.
Longitudinal quantitative variations of Young's modulus and wood density of sugi (Cryptomeria japonica) were evaluated and analyzed whether these wood qualities could be explained by multiple regression models as predictor variables of diameter at breast height (DBH), tree height and longitudinal position of sampling. Three individual trees of sugi were selected from each 5 plus-tree clones in progeny test plantation of 25-years-old. Those trees were felled to measure DBH and tree height and then divided into logs with 2 m until tree top was less than 2 m. Young's modulus and wood density were measured in each logs by dividing each logs into two pieces, a disk of 10cm in thickness and others. The results of ANOVA of Young's modulus and wood density showed that variance among clones was larger than those among longitudinal directions, locations and individuals. However, wood density was influenced by longitudinal direction more than Young's modulus. Multiple regression models of Young's modulus and wood density as predictor variables of DBH, tree height and longitudinal position of sampling showed that ratio of contributions in each clone was high in each wood quality except for one clone in Young's modulus, ranging from 46 to 85%. However, when combined all clones, the ratio decreased to less than 30%. These results suggested that prediction of wood quality of logs felled in non-monoclonal forest stand was difficult by those predictor variables. Thus, to predict the wood quality of logs more precisely, other predictor variables should be considered.
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