Community composition and diversity of land snails along an elevation gradient in the World Natural Heritage Site, Yakushima Island

Abstract

Understanding alpine communities that form along elevation gradients is not only a major topic in community ecology but also provides biological conservation insights into recent environmental changes in alpine ecosystems. In this study, we investigated the community composition and diversity of land snails on Yakushima Island, Japan, which has steep mountainous areas and has been designated a World Natural Heritage Site. As a result of the survey, 3689 individuals of 42 species were recorded at 64 sites, and Bayesian hierarchical models were constructed using a species matrix and environmental data from remote sensing. We found that both land surface temperature, which correlated with elevation, and soil moisture index, which uncorrelated with elevation, altered community composition. Furthermore, species diversity was high at low elevations and decreased monotonically with increasing elevation. This diversity was related to the vegetation types. Thus, the results of these analyses imply that the land snail community on Yakushima Island varies along elevation. This study highlights the need to focus on changes in multiple environmental variables from a conservation perspective and the need to pay attention not only to alpine areas, but also to highly diverse low-elevation areas that are not legally designated as conservation areas.