Abstract
Floristic composition of sown grassland for grazing use was investigated with Braun-Blanquet's “Tabellenarbeit” method and the following results were obtained.
1. Tropical or subtropical weed species mainly dominated on grazing pasture in Okinawa, while temperate weed species dominated in main lands of Japan. However, taking notice of life form composition of whole component species, little difference was found between them.
2. Annual herbs of Compositae dominated on sown grassland for grazing use where had been established afterfelling of Castanopsis Sieboldii forest at Ada in the Okinawa main island. In accordance with the differences in site factor or grazing pressure, grassland developed to Conyza japonica-Gnaphalium japonicum community, Paspalum notatum (bahiagrass) community, Axonopus compressus community, Polygonum longisetum community, Polygala paniculata-Mosla dianthera community, and Rubus Grayanus community.
3. In addition to sown grassland, semi-natural grassland was investigated in the Ishigaki and the Yonakuni island. Zoysia tenuifolia-Hedyotis coreana association dominated in wind-swept area near the coast, while Imperata cylindrica-Paspalum orbiculare association dominated on calcareous soil where had been Imperata cylindrica grassland before establishment. On acid soil grassland where once had been cultivated, Melochia corchorifolia-Paspalum conjugatum community dominated and Heterosmilax japonica-Miscanthus sinensis community dominated where had been Miscanthus sinensis grassland.
4. Similarities among communities mentioned above were clarified according to the combination of plant species. Dynamics of weed communities against soil condition and grazing pasture by animals were also studied.
