A Report on Tree Damages by Avalanche near a Ridge of Mt. Owhira-yama, Southern Hokkaido,

Abstract

The present investigation was done from the point of view of the establishment of forest on the avalanche-hazard slope. The results of the investigation is summarised as follows : 1. Damages of trees by snow-gliding are comparatively little on the low-pitched slope near a round ridge : there are found few examples of break-of-trunk and uprooting.2. The trunk-bending near the ground is conspicuous, and the diameter at the bending is very thicker.3. Each tree species, especially Dake-birch (Betula eramnii) , at the site is larger in both height and diameter growths than on the avalanche-hazard slopes.4. Prevailing wind in growing season is seemed to influence on treegrowth.Moreover, from many observations we suppose the reforestation as follows : 1. The reforestation on the starting part of avalanche is prosperous, because of the possibility of tree-growing and of the removing of Sasa vegetation in sylvicultural engineerings.2. Tree species, used to halt the start of avalanche, must be indigenous to the region and tolerable against snow damages : Itayamaple (Acer mono) , Dake-birch, Japanese beech (Fagus crenata) , and Japanese linden (Tilia japonica) may be good for this purpose.