Alien species in the flora of the nature reserve fund of the flatland part of Ukraine

The current study presents a comparative analysis of the nonnative floras of 23 specially protected natural areas, including 2 biosphere reserves, 5 nature reserves with 9 departments, and 12 national natural parks located in four natural zones of the flatland part of Ukraine. The taxonomic diversity of the studied floras comprises 484 species from 278 genera and 72 families (about 60% of those recorded in the country). The study reveals a considerable variation in taxonomic and typological structures of the anthropophytes from the native flora. The spatial distribution of alien plant species corresponds to the general biological pattern: there is a substantial number of rare species, fewer species have an average constancy, and cosmopolitan species occur rarely. This pattern, consequently, determines a low similarity among the studied nonnative floras. However, the cluster analysis shows almost complete zonal differentiation of the studied floras. The exceptions are the floras of some nature reserve areas with a specific functional-territorial structure. The reference value of the floras of the Ukraine natural reserve fund is questioned.