The distribution of the wildflower Euphorbia adenochlora, a symbol of marshland, was investigated in the “Ukiya no Sato” rural landscape conservation area. The community scale of a total of 2,930m2 was confirmed at 8 points in the marsh with a rich spring flower landscape of the E. adenochlora community. The large population of E. adenochlora present was distributed over the area where the marsh has long not been reclaimed as a rice paddy; thus, it was considered that the marsh had functioned as an ecological refugium for this hydrophytic species. The tendency of high-density growth of E. adenochlora in relatively dry areas within the marsh was indicated as a result of the investigation by the grid lot in the habitat on the largest scale. Features of its location were a domination of Miscanthus sacchariflorus at the upper part, as well as high Saururus chinensis and Stachys aspera abundance. Although there was a similar external community on the site dominated by M. sacchariflorus in autumn, the floristic composition between abandoned paddy fields and habitats that continued to be marshland was different. Since Carex dispalata was dominant at lower-lying areas and the occurrence of E. adenochlora was rare in abandoned paddy fields, it was judged that the former was unsuitable habitat for this native wildflower. Conclusively, the distribution of E. adenochlora was a result of factors including a characteristic ecosystem with spring water sourced in a buried valley, the given history of rural development where non-reclaimed land has been left as refugium for a natural ecosystem to develop, as well as recent landscape conservation activities including burning by a landowner.
