Abstract
The difference in growth and stem form between Sugi under Keyaki and Sugi in the neighboring uniform Sugi forest. The investigation field located in heavy snow region, and the average maximum snow depth ranges from 100cm to 150cm. In comparison with Sugi in the uniform forest, the growth of Sugi under Keyaki was poor, and also seventy percent of them were damaged by snow pressure. Judging from dendrological evidence, this damage occurred in 1983. It is well-known that there is a great risk of snow damage when the ratio of tree height and snow depth (H/S) is less than 2.5. In our case, the average height of Sugi under Keyaki was estimated to be 6m by stem analysis, and that of uniform forest 9.5m in 1983. Maximum snow depth was 270cm. H/S of the former, therefore was 2.2, and the latter 3.5. These results suggest Sugi under Keyaki could not grow enough to overcome the snow pressure damage. It should be noted that two-storied forest consisted of upper broad-leaved species like Keyaki and conifer in its under-story has a potential risk of destruction in the snowy region.
