 The south of the Russian Black Sea region is home to many roadside plant communities which have been characterized by high adventivization and low invasibility. This is largely due to the presence of highly abundant and competitive invasive species in the area. The total projective cover of codominant species from invasive species is also important as it can reduce the levels of adventivization and invasibility. Along the Black Sea coast, the highest concentration of roadside plant communities with relatively more competitive invasive species occurs between the Mzimta and Sheikh rivers under the moderately humid subtropical climate. These communities are found along the Flat River Valleys where the Terrain Ruggedness Index indicates a greater than 50% chance of their occurrence. This article was authored by V.A. Chadeva and R.H. Shigosov.