棚田の畦畔法面草原とススキ草原・シバ草原の種組成の比較

抄録

We examined traditional semi-natural grasslands （TSGs）, i.e., semi-natural grasslands primarily dominated by Imperata cylindrica var. koenigii on the levee slopes of traditional terraced paddy fields in Hyogo Prefecture, Japan.　The species composition of TSGs was compared with that of semi-natural grasslands dominated by Miscanthus sinensis and Zoysia japonica.　Four phytosociological associations （i.e., Arundinario pygmaeae–Miscanthetum sinensis Miyawaki et Itow 1974, Saussureo−Miscanthetum sinensis Suganuma 1970, Geranio–Zoysietum japonicae Suganuma 1966, and Centello−Zoysietum japonicae Itow 1970） were selected as Miscanthus sinensis- and Zoysia japonica-dominated semi-natural grasslands.　The species composition of TSGs markedly differed from that of the four phytosociological associations.　Majority of the differential species of TSGs were annual plants, such as Justicia procumbens var. procumbens, Acalypha australis, and Setaria pumila.　In addition, comparison of life-form spectra revealed that the proportion of annual plants was higher in TSGs than in the four associations.　These findings indicate that TSGs are characterized by the presence of annual plants.