Abstract
Only 15% of beach and dune plants were listed in the 4th version of the Japanese Red List, whereas 46% of salt marsh plants and 36% of sea cliff plants were listed. In contrast, the extinction cases at prefectural levels were higher in beach and dune plants than in sea cliff plants. The extinction rate of beach and dune plants was high in Osaka, Kanagawa, Wakayama and Ibaraki prefecture. As species, Honckenya peploides var. major, Thermopsis lupinoides, Mertensia maritime ssp. asiatica, Fimbristylis sericea, Linaria japonica, Lippia nodiflora and Scutellaria strigillosa were ranked in high risk categories in many prefectural RDBs and the need for conservation was high, although they did not ranked in the Japanese Red List. Local extinction of beach and dune plants might cause decrease of genetic diversity. Additionally, local extinction also may induce collapse of meta-population structure and extinction vortex. Genetic spatial structure and meta-population structure of beach and sand dune plants in Japan are not completely understood. Revealing them is an important theme in future.
