Oshima Island having an area (10 km^2) is situated 50 km off the southwestern corner of Hokkaido. It is composed of the recent triplo volcano and the highest point attains 706 m. The vegetation showes fiesh and mostly unstable and some part is yet bare. The moss communities are well developed on the lava-flows as well as the slope of the volcanic ash and gravel. The Cares flavocuspis community sometimes associated with Aquilegia japonica succeed the former one. According to the deposits of the soil, Arunous sylvester and Maianthemum dila-tatum invade. Often they form the nisular carpet. Or such special slope as not influenced by the NW wind in the winter, the Cirsium kamtachaticum-Angelica ursima and Angelica ursima-Mis-canthus sinensis communities are formed. Berberis amurensis var. japoniea and Sambucus Sieboldiana var. Miquelii communities occur and form thickets in the special localities. The results of the ecological study of the experimental plots prove the communities-Moss, Monocotyle-donous sedge and grass, Dicotyledonous herbs, tall herbs and shruba and developmental states of the volcano. This is excelleat examples of the succession of the plant-covers of the recent volcanoes in Japan.
