Fig. 9

a The principal component analysis (PCA) of the species richness (S), the Shannon–Wiener index (SW), the Margalef index (M) (green), environmental factors (black) and width of wetland herbs distribution (red); bThe redundancy analysis (RDA) of the species richness (S), the Shannon–Wiener index (SW), the Margalef index (M) (red), environmental factors and width of wetland herbs distribution (black)