Abstract
To evaluate the mechanical stability of the Japanese larch (Larix kaempferi Carr) against wind loading, tree-pulling experiments were conducted in Tokachi, Hokkaido. The Japanese larch forests of this region are frequently subjected to strong winds from typhoons. These winds can cause root breakage and damage tree stems. Wind damage is a major source of economic loss in this region. The relationship between angle of inclination at the tree base and the turning moment showed that average angle of inclination was 9.7º at the maximum turning moment Mmax. Correlation analysis revealed that the correlation coefficient between Mmax and the diameter at breast height D was greater than that between Mmax and other elements (tree height (H), slenderness ratio (H/D), stem volume (D2H), weight of branches and leaves (Wcr), stem weight (Ws), total weight (Wt) ). Significant relationships were observed. D was the best index of Mmax. Mmax increased in proportion to the 2.6 th power of D for uprooting and to the 3rd power of D for stem breakage. It was suggested that the mode of failure varied with the diameter; larger trees were uprooted, while smaller tress were broken.
