Sampling Bias, Floristic Differentiation, and Conservation Screening in South Korean Limestone-Area Plant Occurrence Records

Historical occurrence records combine floristic patterns with uneven survey histories. We analyzed 69,707 vascular-plant records representing 2209 standardized taxa from limestone-bearing areas of South Korea in 10 km × 10 km grids. Observed richness correlated strongly with record count across 129 recorded grids (Spearman ρ = 0.996). Among 66 grids with at least 100 records, expected richness in 100 records had little monotonic association with record count (ρ = 0.021), but closely tracked record-frequency diversity (Hurlbert PIE; ρ = 0.992). Observed and standardized richness ranks shared one top-10 grid. Primary 100-record Sørensen dissimilarity had a median of 0.892 and geographic-distance correlation of 0.352. Standardized geographic and composite PCA environmental-distance coefficients were 0.338 and 0.044 (R2 = 0.127), remaining similar after accounting for record counts and source composition. In separate geography-adjusted models, elevation distance was associated with dissimilarity (β = 0.362; exploratory), indicating dependence on environmental-distance definition. Excluding cultivation-flagged taxa preserved dissimilarity ranks (ρ = 0.993). Separate conservation-attribute and alien-occurrence indices identified provisional candidate groups whose membership frequencies depended on resampling cutoffs. These records support descriptive regional comparisons and survey targeting, while recording processes constrain ecological interpretation.