This study is summarized as follows : 1. The site studied is about 840m a.s.l., 45m in slope length, N10° W, and 35° in gradient at Daisetsuzan National Park. 2. There are stands of Japanese birch, Betula platyphylla var. japonica, about 25 years of age, on the artificial slope along Route 273 constructed in 1973. Abelt-transect of 3m x 40m had 12,300trees/ha in density, 2〜10m in height, 1〜13cmin Dbh, and 20.7m^2/ha in basal area (Fig.1). 3. There are scattered young evergreen conifers, 2 species ofPicea and 1 of Abies, 20〜25 years of age under the birch crown (Fig. 2 & Photo. 1). 4. Crowns of the birch on the slope are leaning to the road and therefore, sometimes, trunks fall by both deadweight of crowns and capped wet snow(Photo. 2 & Fig. 4). 5. After thinning experiment, the belt have 4,290 trees/ha in density, 3〜10m in height, 3〜13cm in Dbh, and 14.0m^2/ha in basal area (Fig. 3). 6. Forest vegetation on the artificial slope along the road is improved both by natural agency (succession) and by a little artificial assistance (Fig. 5 & Photo. 3).

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