Phytosociological studies on forest vegetation in western Kyushu, Japan. II. Natural forests of Quercus acuta THUNB. and Abies firma SIEB. et ZUCC.

Forests of Quercus acuta THUNB. (syn. Cyclobalanopsis acuta OERST.) and Abies firma SIEB. et ZUCC. are the climaxes on mountain slopes and ridges, contiguous to the low-elevation Castanopsis cuspidata forests (ITOW, 1971; 1972). Fifty-two relict stands of them were investigated phytosociologically at 13 localities in western Kyushu. The communities recognized were as below. 1. Skimmio-Cyclobalanopsietum (Quercetum) acutae SUZ.-TOK. et SUMATA 1964 Evergreen oak forest, 12 to 18m high and 0.5 to 1 m d.b.h. in canopy trees, prevailing on mid-elevation foggy mountain slopes, ranging from 450m (300m in Tsushima) to 950m. a. Subassociation of Castanopsis cuspidata, ranging from 450m (300m in Tsushima) to 500m altitude. b. Subassoc. of Symplocos myrtacea, ranging from 500m to 950m altitude. 2. Illicio-Abietum firmae SUZ.-TOK. et HATIYAem. SUZ.-TOK.1961 Coniferous forest, 15m to 20m high, found on shallower soils; accompanied, more or less, by evergreen trees and shrubs. a. Subassoc. of Quercus salicina, on flat sites along streams in low elevation. b. Subassoc. of Quercus acuta, on slopes and ridges in the Quercus acuta belt. c. Subassoc. of Hydrangea scandens, being accompanied by fewer evergreen and more summergreen trees and shrubs than the preceding two subassociations; found in higher elevations from 950m to 1100m in the Unzen volcanic area. The geographic distribution of the communities is given in Figs. 1. and 3. and the habitat relationships in Fig. 4