Abstract
We sought to determine the recovery potential of wetland plant communities from seed banks in abandoned dry rice fields. Vegetation was surveyed in three types of systems: abandoned rice fields, harvested rice fields cultivated from abandoned rice fields, and ponds that had once been wet rice fields. Seed banks were examined in abandoned rice fields using the seedling emergence method with three controlled water levels. During germination experiments with soils from harvested rice fields, we discovered the presence of a threatened species, Rotala pusilla Tulasne. This species was not observed in abandoned rice fields. We also found wetland plants such as Lindernia micrantha D. Don in harvested but not abandoned rice fields. In ponds that were abandoned wet rice fields, we found several threatened species, including Alisma canaliculatum A. Braun et C.D. Bouche ex Sam. var. azuminoense Kadono et Hamashima. Plants that grew before the rice fields were abandoned were recovered from the seed banks of abandoned rice fields using cultivation and water-level manipulation, two methods that promote plant growth. Our findings indicated that seed banks in abandoned rice fields are essential to the recovery of waterside vegetation. Therefore, the evaluation of seed banks during the development of abandoned rice fields is an important component of the recovery of plant communities.
