The dissertation is devoted to the research of modern ecological features of the diversity of higher aquatic plants of floodplain ecosystems of the Kyiv urban agglomeration. There are no 26 species of macrophytes in the floodplains of the Dnieper River within the city of Kyiv, which exist in the lists of 100 years ago and 16 species that occurred in floristic collections 50 years ago. Transformation of macrophyte flora over a 120-year period occurred due to the loss of boreal mesotrophic complex of species. Despite of the general intrazonal nature of the flora of higher aquatic plants (dominated by holarctic and eurasian species). It is indicated that a characteristic feature of the modern flora of macrophytes of the floodplained reservoirs of Kyiv is the distribution of alien species. It is noted that the right-bank floodplain complexes are somewhat floristically richer (55 species of macrophytes) (while left-bank –50 species). There is a high similarity of species diversity of macrophytes of floodplain complexes of the right and left banks of the Dnieper (Serensen index = 0.93); with the loss of reservoirs of direct hydraulic connection with the Dnieper River, the role of such species increases: Potamogeton natans, Sium latifolium, Rorippa amphibia, Nymphaea candida, Wolfia arrhiza and Potamogeton heterophyllus; presence of Pistia stratiotes, Nymphaea alba, Lemna minor, Bolboschoenus maritimus, Sium latifolium, Agrostis stoloniferа, Gliceria fluitans – as indicators of the presence of flood water. Analysis of the coenotic structure of macrophyte groups (24 associations of the rank of the association were identified) showed that less than half of the macrophyte species (40%) observed for floodplains of the Kyiv urban agglomeration are cenoses, which is evidence of significant transformation of the shallow water zone and some homogeneity of biotopes. The distribution of reservoirs according to the gradient of nutrient content was estimated, reservoirs with moderate mineral nitrogen content (up to 0.7 N / mg) predominate (they make up almost a third of the studied reservoirs), while the distribution of reservoirs relative to phosphorus phosphate gradient is more uniform. The conducted hydrochemical analysis also allowed to divide the studied reservoirs into 3 types: 1 group – reservoirs with high content of nutrients; group 2 – reservoirs characterized by high phosphate content; 3 – reservoirs with low nutrient content. It is noted that none of the studied reservoirs of the city in terms of nutrient content can be considered as characterized by high quality water. 70% of water bodies covered by hydrochemical analysis would like to be classified as one where water quality is "poor" or "very poor". Analysis of water distribution by species diversity and nutrient load did not reveal a correlation between these indicators; the greatest species richness is characterized by reservoirs from the average indicators of nutrient content (for the quality of water classifications within category 4, class III water quality "contaminated", meso-eutrophic, β-mesosaprobic zone). The correlation between nitrogen, phosphorus compounds and indicator species has been established. Najas marina, Myriophyllum spicatum, Potamogeton perfoliatus, Lemna minor and Spirodela polyrrhiza have a significant relationship with the content of inorganic nitrogen – species that easily withstand anthropogenic eutrophication. For the development of Wolfia arrhiza, Potamogeton lucens, P trichoides, Lemna trisulca, Bolboschoenus maritimus, Batrachium circinatum, Stratiotes aloides and Hydrocharis morsus-ranae anthropogenic eutrophication is a limiting factor. Projections of ecological niches Wolfia arrhiza, Potamogeton lucens, Potamogeton natans, Stratiotes aloides, Hydrocharis morsus-ranae do not go beyond 4 categories of water quality (class III – polluted, meso-eutrophic waters, β-mesophase zone) and are mainly within the 3rd category (class II – pure, oligo-mesotrophic and mesotrophic waters). The rarity component of plant complexes of floodplain reservoirs and watercourses was assessed and a local list of 22 species of macrophytes in need of protection within the aquatic habitats of Kyiv was compiled. It is shown that the local level of vulnerability of macrophytes in urban conditions differs significantly from regional due to significant transformation of the environment: 18 of the 22 studied species in urban habitats show features that meet higher criteria of threat (vulnerability) than regionally and internationally. It is recommended to add to the list of rare plants that need protection at the local level 6 more species of macrophytes, the local sociological status of which is assessed as “Endangered” і “Vulnerable”: Batrachium aquatile, Potamogeton acutifolius, P. obtusifolius, P. trichoides, Callitriche palustris, C. cophocarpa.
