Impact of the invasive species Elaeagnus angustifolia L. on vegetation in Pontic desert steppe zone (Southern Ukraine)

The Irano-Turanian species - Russian olive (Elaeagnus angustifolia L.) - is one of most commonly planted tree in the shelterbelts in southern Ukraine. The consequences of introduction of the species from windbreaks, into areas of different land use in west and central Pontic desert steppe zone are evaluated. The above steppe is unique on a European scale and exists only in some parts of the Black and Azovian Sea coasts. In recent years, the socio-economical crisis in Ukraine (less intensively cultivation, as well as limited grazing) has been responsible for the intensification of the spread of alien tree species outside the windbreaks. Studies were conducted in Kherson Region, in the immediate vicinity of the Black Sea Biosphere Reserve, where the presence of aliens is undesirable. The analysis of phytosociological material (48 releves with and without Russian olive) collected from areas of different land use type and limited human pressure (as abandoned field, former intensively grazed solonetz and extensively grazed desert steppe vegetation) show that E. angustifolia can impede the regeneration of the desert steppe. The species creates favourable conditions for the growth of geographically and ecologically alien nithrophilous weeds.