The alien fraction of the woody flora of Yelanetskyi sSep Nature Reserve, southern Ukraine.
Results of investigations on the patterns of distribution and dispersal of alien species of trees and shrubs in the territory of a steppe protected area, Yelanetskyi Step Nature Reserve (Mykolaiv Region, southern Ukraine), are presented. We registered within this protected area 10 alien woody species. For the most widespread ones (Ulmus pumila L., Gleditsia triacanthos L., Elaeagnus angustifolia L., Robinia pseudoacacia L.), we carried out ecological analyses. In order to establish the scope of impact of ecological factors upon these species, their specificity, and interdependence between ecological factors, the phytoindication method was applied (Didukh, 2012). The results of our analysis conducted on 12 main ecological factors (as outlined by Didukh, 2011), such as soil water regime (Hd), variability of damping (Fh), soil aeration (Ae), soil acidity (Rc), nitrogen content (Nt), salt regime (Sl), carbonate content in soil (Ca), thermoregime (Tm), climate humidity (Om), continentality (Kn), cryoregime (Cr), and light intensity (Lc), show that dispersal of model alien species does not have ecological limitation. However, E.angustifolia and R.pseudoacacia have the strongest capacity to penetrate the steppe communities, especially disturbed ones. Further dispersal of these alien species in the studied area and adjacent territories is hampered only by the integrity of the structure of steppe communities.