Figure 2. The level of invasion measured by the total number of alien species per habitat (S) and the frequency of their occurrence (F) in habitats.

(A) 1–19% locations invaded, (B) 20–39% locations invaded, (C) 40–59% locations invaded, (D) 60–100% locations invaded. For ease presentation F ×10 was used. For explanation of habitat codes see Appendix 1.