Background: To effectively understand and evaluate plant diversity in a specific area and make meaningful comparisons between regions, standardized methods that measure diversity irrespective of survey plot size are crucial. This study proposes a model equation for comparing plant species diversity using the modified Whittaker plots. Plant species diversity was measured in two Gotjawal areas on Jeju Island, where the coexistence of northern and southern limit species significantly impacts diversity. By analyzing the relationship between plant species diversity and environmental factors, the study clarified the characteristics of plant and habitat diversity in the Gotjawal ecosystem.
Results: The species richness of vascular plants, herbaceous plants, and woody plants increased with area and was higher in Jeoji Gotjawal than in Seonheul Gotjawal. Similarly, the species turnover rate (slope value) was higher in Jeoji Gotjawal (4.37) than in Seonheul Gotjawal (3.85). This indicates that the species richness in Jeoji Gotjawal increases more with the expansion of the survey area (1-1,000 m²), reflecting a faster species turnover rate. Additionally, in Gotjawal areas, species richness increased with greater leaf litter depth, elevation, slope, and rock ratio. These results indicate that differences in plant species diversity were attributed to soil environmental factors.
Conclusions: The plant species diversity of Gotjawal, surveyed using standardized methods, was lower than that of forested areas in the central region of South Korea where the same method was applied. Most previous studies on species diversity likely compared diversity without considering a consistent survey area. Therefore, when comparing plant species diversity domestically and globally, it emphasizes the need for the use of standardized survey methods.

Keywords: biodiversity, soil environmental factors, species turnover rate, standardized survey methods, vascular plants