Data from: Taxonomic evenness-area relationships for plant and soil microbes on tropical islands: Patterns and potential mechanisms

Island area is widely known to affect taxonomic richness across trophic levels. However, the effect of island size on species evenness, which quantifies the species abundance distribution, has yet to be explored across taxa, especially for tropical island ecosystems. In this study, we surveyed 20 tropical islands with areas ranging from 2 ha to 406 ha and minimal human disturbance, then measured the taxonomic evenness of both aboveground plant and belowground soil microbial communities. We found that, like the positive area-richness relationship, the taxonomic evenness of the plant community also increased with island area, indicating more stable plant communities on the larger islands. However, the island area did not affect the taxonomic evenness of soil bacterial or fungal communities. Furthermore, the effects of island area on the taxonomic evenness of the plant and soil bacterial communities were mediated through soil factors (e.g., soil pH and salinity). Overall, the contrasting area-evenness relationships among taxonomic groups highlight the importance of dissecting potential mechanisms underlying multitrophic community dynamics; more comprehensive explanations of biodiversity patterns will have critical implications for biodiversity conservation.