Ibatulina Y. Structure of cenopopulations of steppe species in the south-cast of Ukraine.

The thesis is devoted to study of populational structure of steppe plant species belonging to different biomorphs. An various botanical-geographical regions and in the territories with different land use regimen, structure of cenopopulations (age, vitality and spatial structure) has been investigated as well as cenopopulation density. Vitality structure is more susceptible to anthropogenic pressure: depressive cenopopulations were found to be predominant in anthropogenically transformed phytocenoses. In renewing communities and reserves, prosperous cenopopulations of typically steppe species are prevailing, especially cenopopulations of edificators. An respect of spatial structure, there is observed a formation of contagions type of species distribution in phytocenoses exposed to anthropogenic pressure as well as in phytocenoses in different stages of demutation. Forming of regular type of species distribution. Investigations of seasonal and year-after-year dynamics of structure of introductional populations have been conducted in artificial steppe phytocenoses, which enabled to determine similarity between their parameters and indices of natural cenopopulations.