GEOBOTANICAL COMPARISON BETWEEN TWO JAPANESE VOLCANOES: MT. FUJI AND MT. ASAMA

Abstract

Mt. Fuji and Mt. Asama are two of the highest Japanese volcanoes. reaching 3776 and 2542 m a.s.l. respectively. The former is dormant but the latter is an active volcano. This study is based on our own unpublished data, which inc1udes a total of 152 phytosociological relevés. and on previous studies of the vegetation of both volcanoes. On the basis of the data collected al different times a geobotanical comparison between the two vo1canoes as regards their high moutain regions was made. In this region the following belts may be distinguished on both volcanoes: - a subalpinc belt, characterized on its upper zone by shrub communities with some Ericaceae, larch (Larix leptolepis), Salix reinii and other dwarf woody species; - an alpine belt, where there is scattered herbaceous vegetation, mostly dominated by Polygonum weyrichii v. alpinum. In this belt on Mt. Fuji, the following communities may be distinguished: the Arabis serrata-Polygonum alpinum community on the lowest altitudes; the Stellaria nipponica-Polygonum alpinum community and at higher altitudes a very sparse poor community characterized by Cassiope lycopodioides. In the highest region up to the summit there are moss and lichen communities only. On the southeastern side on the 1707 ash and scoria there is pioneer vegetation dominated by Cirsium purpuratum and Campanula hondoensis. On Mt. Asama the high-mountain vegetation is dominated by the Polygonum alpinum community. It occupies a narrower belt. Here the volcanic activity doesn't allow the vegetation to reach the top. In the highest region of the volcano there is a bare sterile zone. The differences found in the altitudinal distribution of vegetation on the two volcanoes can partIy be attributed to the fact that one (Mt. Fuji) is dormant, while the other (Mt. Asama) is active. On active volcanoes the ecological factors related to the volcanic activity have a strong influence on the vegetation and its distribution.