Plant Community Characteristics Associated with the Occurrence of the Endangered Epiphytic Orchid Dendrobium moniliforme on a Coastal Cliff in Korea

Cliff habitats support distinctive plant communities, yet the vegetation characteristics associated with the natural occurrence of Dendrobium moniliforme remain poorly understood. This study characterized plant communities associated with the occurrence of D. moniliforme on a coastal cliff of Seonyudo Island, Republic of Korea, using unmanned aerial vehicle (UAV)-based vegetation surveys. A total of 56 plots, comprising 13 occurrence and 43 absence plots, were surveyed, and plant diversity, taxonomic composition, and life-form composition were compared between the two groups. Species richness was significantly lower in occurrence plots, whereas Shannon diversity was significantly higher. Plant community composition differed significantly between occurrence and absence plots (PERMANOVA, R2 = 0.075, p = 0.0005), with several species contributing to the observed compositional differences. Life-form composition also differed significantly between the two groups (PERMANOVA, R2 = 0.045, p = 0.028), with occurrence plots tending to show greater relative cover of chamaephytes, hemicryptophytes, geophytes, and epiphytes. These findings suggest that, within the studied coastal cliff, the occurrence of D. moniliforme is associated with differences in surrounding vegetation composition rather than simply greater species richness, providing site-specific baseline information for habitat characterization and conservation.