口永良部島の照葉二次林内の露岩に付着する維管束植物の種組成と種多様性

抄録

Kuchinoerabujima Island is a volcanic island in Japan, with many areas covered by secondary evergreen broad-leaved forests dominated by Castanopsis sieboldii.　The surface geology of these forests is mainly classified into the following two types:（1） lava flow, where many exposed rocks are found;and （2） tephra deposit, where no exposed rocks exist.　I examined the species composition and richness of vascular plants growing on exposed rocks in the secondary evergreen broad-leaved forests on the lava flow of the island.　In total, 54 species were observed on the 64 exposed rocks.　Comparison of life-form spectra of the species composition revealed that relatively large exposed rocks were characterized by the presence of tree and shrub species.　The sample scores for the first axis obtained by the detrended correspondence analysis were significantly correlated with rock area.　A highly positive correlation between the number of species and rock area was observed for all species, tree species, shrub species, and climbing plant species.　These findings indicate that the species composition and richness are affected by rock area.