谷津田沿いの斜面地における半自然草地の分布と景観構造および局所立地条件との対応

概要

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Sloping meadows lying beside rice paddy fields have among the highest floristic species richness in the hilly agricultural ‘yatsu’ landscape in Japan. Little is known about factors, especially the non-local-scale factors, affecting the distribution of these semi-natural meadows. I investigated the relationships between the landscape structure and local environmental variables, and the species distribution in the sloping semi-natural meadows in Chiba prefecture, Japan. I surveyed species in 54 plots measuring 1 X 10 m. TWINSPAN classification defined four groups of plots. One group consisted of significantly greater numbers of species characteristic of the Miscanthetea sinensis community than in the other 3 groups, indicating floristically diverse semi-natural meadows. The distribution of plots was well explained by non-adjacency of paved farm roads, adjacency of secondary woodland in the 1940s, and >34% relative light intensity in the meadows. Both present local environmental conditions and present or past landscape patterns determined the distribution of this semi-natural habitat. These results will contribute to the selection of appropriate management strategies to conserve this valuable habitat. Keywords: linear habitat, characteristic species of Miscanthetea sinensis, Yatsu landscape, adjacent land use, land use history, paved farm road