A conservation assessment for protected area designation based on floristic data of multiple wetlands in eastern Hokkaido, Japan

The Nemuro region, located in northeastern Japan, has many lowland wetlands including fragmented wetlands adjacent to pastures and residential areas in a mosaic pattern. Currently, these wetlands are proposed to include new protected areas when existing nature reserves expand. To conserve the biodiversity of such wetlands, it is necessary to compare their biodiversity comprehensively. In this study, we conducted floristic surveys and a literature review to assess the conservation importance of 34 wetlands in the region by complementary analysis using Marxan software. The results were interpreted based on species richness and floristic similarities using NMDS analysis. A field survey of eight wetlands recorded 323 taxa, including 42 Red List plant taxa, and provided new localities of Sparganium natans and Cirsium charkeviczii , rare species in Japan, and eastern limit record of Eriocaulon taquetii . Complementary analysis based on the occurrence records of 210 wetland plant taxa revealed a conservation gap: 6 of the 15 important wetlands were not covered for the existing nature reserves. Although most of the 15 were species-rich wetlands, three species-poor wetlands were also considered important to ensure floristic diversity. In addition, two species-rich wetlands were considered unimportant because their flora were not unique, possibly because of wetland fragmentation.