The conservation ecological study on the diversity of plants in terrace paddy

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Terrace paddy fields are the typical landscape of mountainous rural regions. As these paddy fields are being abandoned because of their non-eficiency of rice production, plants distributed their are threatened. In this study, to conserve the diversity of the flora, the species diversity in terrace paddy fields was compared to that of the pddy fields in plain and the genetic diversity of two threaened paddy weeds was clarified. The species diversity on the terrace paddy levees in Miyadzu, Kyoto and on the paddy levees in plain in Seika, Kyoto was investigated in 2000 and 2001. On the levees of the terrace paddy in Miyadzu, 75 species were there and 71 species in Seika. The species diversity index of the terrace paddy levees was hegher than that of the paddy levees in plain, but the ratio of naturalized plants was lower on the terrace paddy levees than on the paddy levees in plain. The levees of the paddies in plain were suffered catastorophic destruction by the reconstruction of levees and as the result the vegetation was destroyed and the diversity index was decreased. The distribution of Blyxa ceratosperma was distributed in only tow terrace paddy fields, B. japonica and O. japonica in seven paddies. The genetic diversity of B. japonica and O. japonica was analyzed by RAPDs. B. japonica was clearly differentiated to the local populations and the genetic diversity of O. japonica was higher than that of B. japonica. These three species were reported to be allogatmous, but from the results of the experiment these were suggested to be autogamous plant.