Historical overview of the studies of alien flora of Ukraine

This review has shown that the alien fraction of the Ukrainian flora have been identified and studied comprehensively. Thus, a total richness of alien fraction is about 1,000 species. The structure, typical trends, and regional peculiarities of this component of the Ukrainian flora have been analyzed. The main results of investigations are summarized. The alien floras of some regions, cities and towns, protected areas of Ukraine have been studied. The species composition of some habitats, partial floras with a high abundance of non-native plants, tolerance to anthropogenic influences, the segetal potential, and the role in developing of the human-made biotopes and in evolution of the plant cover have been determined. The changes in the species composition over 160 years, and the trends forming the stable and unstable elements of the alien flora of Ukraine, have been shown. The peculiarities of the distribution of archaeophytes and neophytes of the regional floras and urban floras as latitudinal gradients have been revealed. The plant invasions and expansions of 30 species have been reconstructed, analyzed and reviewed. A group of highly invasive potential species is selected. Some important characteristics of alien species, such as their activity in plant communities and their ecological effects, the trends of distribution and abundance, the participation and role under the influence of anthropogenic environmental change or climate change in various types of biotopes and geographical zones etc., have been analyzed