Floodplain ecosystems take on the role of active areas of biodiversity and provide many “ecosystem services”, as evidenced by a number of European scientific references. A biodiversity analysis of river floodplains in six European countries within the temperate zone has shown that the floodplains are habitats with a high-level of structural and functional dynamics. The level of their conservation reflects the floristic diversity of forest territories, which is especially important for subarid areas. Recently, a comparison of bioecological characteristics of flora in floodplain forest areas and treeless territories was conducted on the floodplain landscapes of a subarid region of Europe. The valley-terraced landscape of the Samara River, a tributary of the Dnieper can serve as a reference site of native plant complexes of subarid territory in Eastern Europe. Despite long-term anthropogenic transformation, the landscape has retained a significant phytodiversity level. The flora of the Samara River area includes 887 plant species. Of these, 177 species belonging to the rare and endangered categories. The floodplain landscape is the richest in species and most diverse part of this complex. The flora of the Samara floodplain includes 728 species (including 132 rare ones), of which 631 grow in forest communities, and 487 – in anthropogenically transformed, treeless floodplain areas. As part of the forest flora, the number of tree and shrubby species, scyophytes, hygrophytes, and megatrophs significantly increases compared to treeless sites, and the number of ruderal plant species decreases. The floristic composition of the floodplain forests of the subarid region is much richer and more diverse than the flora of the treeless floodplain areas, and this should encourage measures for their protection and restoration. Afforestation of floodplain territories within the steppe zone of Ukraine should be a priority in comparison with other landscapes. For the protection of the flora studied, a scientific justification for creating the National Park "Samara Bor" was prepared. Under the conditions of anthropogenic and climatic impact, this article is of great global importance for attracting the attention of specialists, authorities and society to the protection and restoration of biodiversity in the most valuable landscapes.

The creation of reservoirs in river valleys for the accumulation of fresh water has been and remains an important issue around the world. This process has both positive and negative consequences for people and nature. Significant changes in the regime of rivers and their valleys, flooding of meadows and forests, flooding of soils and changes in the composition of flora and fauna of adjacent territories are taking place. In this article, we consider the restoration of the biodiversity of a site of disturbed lands after the creation of one of the first large reservoirs in Europe – the Dnieper (Zaporozhe) on the River Dnieper, which has existed since 1933. The territory of the Samara floodplains was formed on the floodplain of the mouth of the Samara River, as a result of which the territories of various forest, meadow and bog biotopes were flooded. For almost 90 years, new biotopes have been developing, and populations of plant and animal species, especially waterfowl, have been renewed and enriched. In the conditions of climate change and anthropogenic pressure, the existence of this territory has fallen into question. To control the conservation of biodiversity, it is necessary to apply various management methods, one of which is creation of nature reserves. The article presents the results of a complex of scientific studies that were carried out during the zoning of the regional park Samara Plavni to improve the management of the protection of water areas and river banks. We have investigated: hydrological features, species diversity of the flora and coenotic diversity of the vegetation, fauna of aquatic invertebrates, and terrestrial vertebrates. Zoning of the Regional Landscape Park was based on the composition of stable components of ecosystems. When applying the protected regime in different zones, conditions will be created for the preservation of habitats of species, including those protected in Europe: higher plants (Senecio borysthenicus (DC.) Andrz. ex Czern., Tragopogon borystenicus Artemcz.), reptiles (Emys orbicularis (Linnaeus, 1758), Vipera renardi (Christoph, 1861)), birds (Aythya ferina (Linnaeus, 1758), Vanellus vanellus (Linnaeus, 1758), Haematopus ostralegus Linnaeus, 1758, Numenius arquata (Linnaeus, 1758), Alcedo atthis (Linnaeus, 1758), Lanius excubitor (Linnaeus, 1758)), mammals (Lutra lutra (Linnaeus, 1758)). Such changes would increase the implementation of the reproductive potential of all species without exception in the studied ecosystems.

In this article, the current and former distribution of higher aquatic vegetation has been analyzed for floodplain lakes, arenas lakes and third terraces lakes in the valleys of large and medium North-Steppe Dnieper rivers. The article is devoted to the current state analysis of the higher aquatic vegetation at North-Steppe Dnieper lakes, its dynamics over a long-term period, as well as the determination of the nature and extent of anthropogenic-climatic changes in vegetation. Anthropogenic influence is a major threat to the development and functioning of most aquatic ecosystems. Since the twentieth century, it has been intensified by trends to long-term climate changes, which are also largely result of human activity. Increasing temperature of the winter season does not contribute to snow accumulation. Reduction of snow accumulation (frequent thaws during the winter), regulation of river flow (formation of a reservoirs cascade and ponds) and accumulation of melt water in artificial reservoirs led to the smoothing of the peak of the spring flood. Thus, the factor that provided spring washing of floodplain lakes, limited their overgrowing by air-water vegetation and their waterlogging disappeared. The anthropogenic factors that influence negatively include: intensification of agriculture, plowing of coastal areas, unreasonable land reclamation, overgrazing, development of transport and engineering infrastructure, urbanization, recreation, and chemical pollution. The presented data was obtained on the basis of processing our own research materials of 2009–2018 and literary and archival materials analysis (the herbarium of the Dnipropetrovs’k National University and the archive of the Research Institute of Biology). Natural Northern Steppe Dnieper lakes are located mainly in river valleys, so the study area was conventionally divided into sections: the large river valley (Dnieper) and the middle rivers valleys (Samara and Orel). Three ecological groups of macrophytes were reviewed and compared: hydatofites (submerged species), pleistophytes (species with floating leaves) and helophytes (air-water species). The vegetation of Dnieper floodplain lakes practically did not change for all three formation groups. The number of immersed plants communities within the floodplains of medium-sized rivers has decreased by three. The pleistophytes and helophytes associations decreased to fragments of associations. The lakes vegetation within the sandy Dnieper terrace practically did not change for all three formation groups. The submerged lakes plants associations within the sandy medium-sized rivers terraces have been reduced by two. As part of the lakes vegetation on the Dnipro saline terraces, fragments of associations of the two species are considered extinct. A new association of southern adventive species Ruppia maritima L. has appeared within the limits of the middle rivers saline terrace. Changes in higher aquatic vegetation are characteristic of all types of lakes. Changes occur in the direction of crowding out higher aquatic vegetation communities by airborne plant communities. The consequence of the anthropogenic-climatic transformation of aquatic ecosystems is increased mineralization, siltation, and, as a result, intensive overgrowing of lakes by aboriginal and adventive species with a wide ecological amplitude (replacement of sensitive to environmental changes species).

This article is devoted to the typology of lakes of the North-Steppe Dnieper. In developing the typology of lakes, the parameters were taken into account: landscape location, hydro-chemical and hydro-biological characteristics and the degree of their anthropogenic transformation. The data presented are based on the processing of stationary and route research materials from 1998 to 2018 on the lakes of river valleys: Dnieper, Samara, and Orel. Hydrological indicators are analyzed according to the literature, cartographic and archival data of the Dneprodiprovodkhoz Institute and the Biology Research Institute of Oles Honchar Dnipropetrovsk National University. Floristic studies were carried out using general botanical methods of collection and herbarization, and in the study of typical aquatic flora - special hydro-botanical methods. Geo-botanical studies were carried out according to geo-botanical and special hydro-botanical methods. The article presents the hydrological and hydro-botanical features of the lakes of the valley of a large river (Dnieper) and medium rivers (Samara, Orel). Lakes are located exclusively in valley-terrace landscapes in the northern part of the steppe zone of Ukraine. Despite this, based on cartographic materials, we proposed zoning of the territory of the lakes of the North-Steppe Dnieper according to the criteria: their location in lake regions, in various landscapes and the degree of anthropogenic transformation. The following districts and subareas were identified: Dnieper Lake District (Dnieper floodplain lake subarea with slight flooding of the floodplain, Dnieper Lake subarea of floodplain terraces, Dievsky floodplain lake subarea); Samara Lake District (Lake Subarea of Samara Coniferous forest, Lake Subarea of Estuary part of Samara); Orel Lake District. Lakes are located in various physical and geographical conditions of the floodplain, arena and third saline terrace. The typology of the lakes of the North-Steppe Dnieper basin was developed on the basis of regionalization of the location of the lakes, distribution according to the ecological and topographic profile, hydrological, hydro-chemical regimes, degree and nature of overgrowing. 11 types of lakes are identified based on the above criteria. 6 types were identified for the valley of a large river: floodplain lakes (3 types) with a long-flow regime, lakes of the second (sandy) terrace (2 types) and highly mineralized lakes of the third (saline) terrace. 5 types were identified for the valleys of middle rivers: floodplain lakes (3 types) with an episodic short-burial regime, lakes of the second (sandy) terrace (low-mineralized) and excessively mineralized lakes of the third (saline) terrace.