16 巻 (1999) 1 号 p. 57-67
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.