2022 Volume 39 Issue 1 Pages 1-13
We examined the composition and abundance of buried diaspore （seeds and oospores） in the soils and discussed their possibility for restoration of hydro- and hygrophytes in abandoned terraced paddy fields in a mountainous region of Sado Island, Niigata Prefecture, Japan. Laboratory sowing test was conducted using soil samples collected at depths of 5-15 and 15-25 cm （0.024 m3 in total） in reed and forest stands that had been abandoned as paddy fields ca. 40 years ago. We recorded 26 plant species and 1357 individuals in the laboratory sowing test. Based on the best models selected by GLM in the laboratory sowing test, higher water level and deeper soil sample were significantly associated with fewer total number of plant species and individuals germinated except submerged plants. The results of our study suggest that submerged plants, including many endangered species by Japan’s Ministry of the Environment, e.g., charophytes （Chara braunii and Nitella spp.）, can be restored from deeper soils （15-25 cm） in reed stands, setting the water depth 5-15 cm. We observed 10 species of endangered hydrophytes in the laboratory sowing test and/or neighboring biotopes in the study area. As the soil diaspores banks in abandoned terraced paddy fields of the study area may be coming up to their expiration of life span, various methods should be applied to restore and conserve hydro- and hygrophytes using soil diaspore banks and biotopes those had been recreated from abandoned terraced paddy fields several years ago.
