Figure legends

Fig. 1. Representativeness of study sites. (a) Distribution of study sites across the southern part of the Korean peninsula. (b) Distribution of study sites across the global vegetation biomes defined by the Whittaker classification.
Fig. 2. Conceptual diagram of the analysis steps and data flow in defining the floristic zonation (Kreft and Jetz, 2010).
Fig. 3. Results of the self-organizing map (SOM) analysis for 9 × 9 SOM map. (a) The neighbor distance plot or U-Matrix indicating the distance between each node and its neighbors. (b) The classification of the training samples according to the SOMs.
Fig. 4. Four floristic zones mapped to the southern Korean Peninsula, derived using plant distribution data. The straight and solid lines represent the named historical floristic regions. The lines dividing the historical floristic regions have previously been used to explain the observed distribution of plants on the Korean Peninsula (e.g., north, central, and southern Korean Peninsula).
Fig. 5. Comparison of geographic and climate factors in the derived floristic zones on the southern Korean Peninsula. (a) latitude; (b) longitude; (c) mean annual temperature; (d) annual precipitation; (e) warmth index; and (f) coldness index. Median values are marked inside the boxplots, errors bars indicates the 90th and 10th percentiles, and the points outside of the error bars indicate outliers. A Tukey post-hoc test revealed significance groups, represented by letters (p < 0.05).
Fig. 6. Analysis of composition ratios for physical factors in each floristic zone on the Korean Peninsula. (a) Parent material; (b) topography; (c) effective soil depth; and (d) soil texture.
Fig. 7. A Venn diagram showing the relationships between plant distributions in each of the four floristic zones. Numbers represent individual taxonomic groups.
Fig. 8. Comparison of the composition of specific plant families in each floristic zone. As shown in Fig. 7, there were 1,099 taxa that appeared in all 4 zones. The specific plant species in Zones I, II, III, and IV numbered 72, 25, 192, and 404 taxa, respectively.