2017 Volume 34 Issue 1 Pages 23-37
We conducted a belt-transect survey on sandy coasts in the eastern part of the San’in Region to assess the species composition and species richness of dune plant communities, the community composition and community diversity of dune vegetation, as well as the arrangement of communities and the distribution of threatened dune species along the shoreline-inland gradient. Seven study sites were selected, and 287 vegetation samples were analyzed mainly by two-way indicator species analysis and detrended correspondence analysis. The results showed that the following three communities, each with a different composition of dune species, were arranged from the shoreline to the inland areas: Carex kobomugi community, Vitex rotundifolia community, and Juniperus conferta community. Species richness of dune species was highest in the V. rotundifolia community, but the differences among the three communities were not as conspicuous for dune species as they were for the inland species, which clearly increased toward inland areas. Several threatened dune species occurred in different communities: Heliotropium japonicum in the C. kobomugi community; Orobanche coerulescens and Viola grayi in the Vitex rotundifolia community; and Veronica ornata and Scutellaria strigillosa in the J. conferta community. Community diversity was positively correlated with the beach-dune width and dune height, indicating that the sandy coasts with larger dunes potentially hold higher community diversity. Community composition was also found to vary mainly according to the dune height of the sandy coasts, and few sandy coasts included all types of communities. These results suggest that preventing the reduction of beach-dune habitats to maintain higher community diversity in each sandy coast and preserving sandy coasts that have different types of community composition throughout the area are important for the conservation of dune floras in the eastern part of the San’in region.
