Floristic composition of the Fagus japonica communities and their habitats were investigated in summergreen broad-leaved forests in the Tanzawa Mountains. The communities were all observed on upper sideslopes above erosion fronts and were classified into four associations based on phytosociological method. Three of the associations were mainly distributed in the West Tanzawa Mountains, each with different vertical distributions, as follows : Styraco shiraianae-Fagetum japonicae (400 〜 900 m) ; Fagetum crenato-japonicae (800 〜 1200 m) ; Corno-Fagetum crenatae (subassociation of Fagus japonica) (1050 〜 1300m). The fourth association was Veronico-Fagetum crenatae (subassociation of Fagus japonica) (1050 〜 1300m) and was distributed in the East Tanzawa Mountains. In this area, since the understory has been changed through the impact of Sika deer (Cervus nippon), the association was characterized by plants disliked by Sika deer. Fagetum crenato-japonicae was classified into two subassociations : typical subassociation and subassociation of Hydrangea hirta. Veronico-Fagetum crenatae (subassociation of Fagus japonica) was classified into two variants : typical variant and variant of Pterostyrax hispida. All four under units varied in their species composition, paralleling changes in their microtopography on the upper sideslope.
Distribution and developmental patterns of floodplain willow communities were investigated along the Kinu River, which has meandering zone and alluvial fan zone. Community structure, species composition, and alluvial materials of the ground surface were surveyed in 131 stands. 11 Salicaceous species were observed in the study area, and most stands were dominated by 5 major species (Salix chaenomeloides, S. subfragilis, S. gilgiana, S. sachalinensis, S. serissaefolia). Distribution of dominant stands of each species were related with riverbed types ; S. chaenomeloides, S. subfragilis, and S. gilgiana, in meandering zone, S. sachalinensis and S. serissaefolia in alluvial fan zone. Furthermore, some developmental patterns of willow community were clarified in different dominant species. S. subfragilis and 5. gilgiana formed dense juvenile stands on silty or sandy alluvial materials. The stands with these species did not become more than 10m height, even when stem diameter reached to 20cm. On the other hand, S. serissaefolia formed sparse juvenile stands on gravely alluvial materials, and they developed more than 10m height on higher floodplain. These developmental patterns of community were adaptable for river dynamics of their distribution area. S. sachalinensis that had wide distribution area, indicated various patterns of community structure and species composition. The results show that the distribution pattern of willow community is restricted not only by the soil texture suitable for seedling establishment, but also by the relationship between the developmental patterns of community and river dynamics. Especially, development of tree community more than 10m height was dependent on the formation of higher floodplain that is not affectedly flood disturbance.
The floristic composition of Diapensia lapponica var. obovata community on Mt. Halla, Cheju Island, Korea was surveyed, and compared with Arcterio - Loiseleurietum Ohba ex Suz.-Tok. 1964 which can be seen in Japan. D. lapponica var. obovata community on Mt. Halla did not have alpine evergreen and semi-evergreen dwarf shrub species such as Cassiope lycopodioides, Empetrum nigrum var. japonica, and Loiseleuria procumbens which were common in Arcterio - Loiseleurietum. In addition, D. lapponica var. obovata community on Mt. Halla had epilithic species such as Tofieldia coccinea var. kondoi, Saxifraga fortunei var. incisolobata, and Primula modesta, which distribute below subalpine zone in Japan. This community distributed on the slightly wet site of northern face on precipice, whereas Arcterio - Loiseleurietum distributed on the windward dry site. Therefore, these features are very different from Arcterio - Loiseleurietum in Japan. From these reasons, D. lapponica var. obovata community on Mt. Halla was regarded as a new association, Tofieldio coccineae - Diapensietum. In the viewpoint of flora, this association lacked the elements of Northeast Asia and North Pacific, while these were main elements of Arcterio - Loiseleurietum. On the other hand, Tofieldio coccineae - Diapensietum has some similarities to the epilithic vegetation below subalpine zone such as Potentillion dickisii Ohba 1973, because of containing some epilithic species such as T. coccinea var. kondoi, S. fortunei var. incisolobata, P. modesta. Thus, Tofieldio - Diapensietum is considered as a unique association characterized by the coexistence of alpine dwarf shrub species, D. lapponica var. obovata, and some epilithic species.