On the relative importance of landscape variables to plant diversity and phylogenetic community structure on uninhabited islands, South Korea

Abstract

Although there have been methodological advances in the analysis of biodiversity and landscape properties, most studies in landscape ecology primarily explore whether certain landscape properties, such as island area and isolation, have universal effects on species-centric measures. We assessed how landscape variables drive species richness, phylogenetic diversity (PD), and phylogenetic community structure. Moreover, we explored the dominant processes structuring plant community assembly, including phylogenetic community structure. We used plant data from 235 uninhabited islands in the western and southern seas, South Korea. Species richness, Faith’s PD, and standardized effect size of mean pairwise phylogenetic distance (SES.MPD) were quantified for three plant groups, all, woody, and herbaceous plants for each island. Island area, distance from mainland, habitat heterogeneity, and structural connectivity were also calculated to examine the relationships between indices of plant diversity and community structure. The relative importance of landscape variables differed among indices of diversity and community structure as well as among plant groups. Island area and distance from mainland were the main drivers of species richness and PD across plant groups, whereas distance from mainland significantly affected community structure measured by SES.MPD. We found that the community structure in islands farther from mainland showed phylogenetic clustering patterns driven by niche-based deterministic processes across the three plant groups. We found that community structure analysis provides more information related to ecological processes and assembly mechanisms than diversity indices alone. Therefore, we recommend that community structure analysis with plant diversity should be implemented as an additional measure of biodiversity for landscape ecology and for conservation planning in island ecosystems.