Rozenblit Y. Ecomers of the Dniester canyon

The dissertation is devoted to a comprehensive study of vegetation and habitats of the Dniester canyon, to the ecological and topological specifics of their distribution (typification of ecomers), assessment of environmental factors, analysis of the degree of external factors, scientific significance, evaluation of habitat loss, conservation perspectives. Based on the results of the phytosociological data, including data from archives and literature sources, the syntaxonomic composition of the natural vegetation of the Dniester canyon was established, which is represented by 18 classes, 24 orders, 41 alliances and 70 associations. The classification scheme of biotopes includes five types: (D – coastal and aquatic vegetation; E – grassland habitats (meadows, steppes, heathland); F – shrubs; G – forests; H – chasmophytic biotopes). Based on the method of synphytoindication, the leading environmental factors for the differentiation of ecomers are established. On the slopes of the Dniester canyon the leading factors of the forest habitats differentiation are the climate humidity, thermal regime and cryoregime. Whereas for grassland habitats – the variability of soil moisture, which is closely correlated with the salt regime and acidity. Within the floodplain, the leading factors are variability of soil moisture, humidity and aeration. We proposed the scheme of ecomers within mesocombinations with the names of sigma-syntaxa, based on the assessment of the topological distribution of habitats. They are represented by 16 sigma-syntaxa. It is established that highest β-diversity is characteristic for the grassland types of ecomers, which are mainly distributed within the Podilski Tovtry National Park, while especially valuable habitat types are formed by forest-type ecomers, which are mostly concentrated in the Dniester Canyon National Park and the Khotyn National Park.. The general patterns of distribution of plant communities within the floodplain and canyon slopes are analyzed. We made a synphytoindication assessment of the environmental gradient of each of the factors. It was found that the complexity of the lithological and geomorphological structure of the canyon determines the character of vegetation within the macrocombinations. We found 129 rare vascular plant species listed in the red lists s and 38 аssociations are included to the Green Data Book of Ukraine; 15 habitat types are listed in the Resolition 4 of the Bern convention. We classified the habitats based on their threats and values.