Comparison Study in the Clear Wood Estimation of the Beech tree trunk(Fagus orientalis Libsky)

Fagus orientalis is a valuable deciduous tree species mainly distributed in northern of Iran.There is great demand in the market for its log especially for knot-free logs. The classification of roundwood is inextricably linked to the measurement of a particular single wood defect. The appearance, location, and number of defects are important in the quality evaluation of logs and sawn timber, and the most important defects are knots. To evaluate the defects of trees, destructive methods (cutting) and non-destructive methods (CT scans) are used. The purpose of this study was to calculate clear wood by four models and compared to CT- scan. Fifteen stems of oriental beech trees were studied. The Pearson correlation coefficient and the Kolmogorov-Smirnov test have been used to check the normality of the data and the correlation between the parameters. The results show that the detection of CT- scan is high at the organs have a significant difference in the density. The accuracy of detection and evalution is high in the CT-Scan method. The results show that there is a high correlation between all methods of estimating clear wood. The most correlation coefficient was obtained between the fourth model and CT-Scan method(r=0.994) which their clear wood estimation are the same. Among the studied models, the first model (∆r=Ws-Ls) which is based on the external indicator is more suitable for evaluating of the beech clear wood in the log grading process