2021 Volume 38 Issue 1 Pages 17-35
Plant communities on rocky coasts are established in response to the shoreline-to-inland transitional environmental gradient as well as to various environmental conditions on rocky shores. In addition, rocky coast is an essential habitat for threatened and endemic plants. Our research aimed to study plant communities comprising sea cliff herbaceous vegetation and their environmental conditions, and to clarify the relationships between communities and important conservational plant species on the Miura Peninsula, Kanagawa Prefecture, eastern Japan. Using modified TWISNAPN, vegetation data of 123 stands were divided into 11 communities. Almost all communities were equivalent or similar to the associations already known around the study area （e.g., Fimbristylidetum ferrugineae Ohba 1970 and Chrysanthemo-Miscanthetum condensati Ohba 1971）. On the other hand, some communities differed from the known associations in the Kanto region. Five communities were established on wet elevated abrasion platforms or wave cut benches, and the environmental conditions of these communities show unique hydrological conditions and water quality. The other six communities were established on sea cliffs, and the environmental conditions of these communities showed unique soil characteristics and intensities of location stability caused by slope gradient and elevation differences. In 7 of the 11 communities, there were 13 national or prefectural endangered species and 8 endemic species, and almost all of these were combined within specific communities. The locations of these communities were gently sloping and likely to be sensitive to human activity. To conserve herbaceous communities and the diversity of plant species on rocky coasts, it is important to focus on differences in site fragility across communities.
