Dendroflora diversity in the coastal zones of the Dnipro river within the Northern steppe subzone of Ukraine

Coastal tree and shrub vegetation is an important component of river catchment ecosystems, it performs a wide range of ecological functions and ecosystem services; their effectiveness largely depends on species richness and diversity. Coastal habitats are among the main centers of biodiversity, but they often perform a function of centers of active anthropogenic activity and undergo significant transformation. The creation of a cascade of the Dnipro reservoirs (Kamenske, Zaporizhia (Dniprovske), Kakhovske reservoirs) has already caused the transformations of the Dnipro river flow regime and all biological components of the aquatic and wetland ecosystems in the Northern steppe subzone of Ukraine. In the current period, on the background of global climate change, dendroflora transformation on this territory is enhanced by the anthropogenic impact of industrial cities (Kamenske, Dnipro, Zaporizhzhia). Assessment of dendroflora diversity in coastal zones was carried out within the protective strip of the Dnipro river (100 m): in native phytocenoses; semi-native vegetation associations; water protection plantings; public green spaces (excluding private plots and collections). It was determined that the dendroflora in the coastal protective strips of the Dnipro river within the Northern steppe subzone of Ukraine is characterized by significant taxonomic diversity and includes 184 plant species (excluding their decorative forms) belonging to 37 families. The highest species saturation was typical for the following families: Rosaceae (40 species), Salicaceae (23 species), Fabaceae (11 species), and Oleaceae (9 species). The dendroflora consists of 61 tree species, 78 shrubby species (including lianas) and 45 species that can be represented by both tree and shrubby forms. The highest species richness was recorded in public recreational green spaces: 181 species (98% of the total species number). The coastal tree and shrubby associations included 8 species that belong to rarity ones (the Red List of the Dnipropetrovsk region). The coenomorphic spectrum of dendroflora in coastal protective strips is dominated by culturants (70.7%), autochthonous silvants (19%), stepants (3.2%), silvomargoants (species of forest margins, 4.3%), pratants (1.6%), and paludants (1.1%). There is the dominance of mesophytes (55%) and species with a wide range of adaptations to the humidification conditions of hygrotopes in hygrospectrum (22.8%); mesotrophic species among trophomorphs (53.8%), and sciogeliophytes in heliospectrum (57%). In the dendroflora of the coastal zones of the Dnipro river, alien species completely predominated (71% of the species composition). Among them, 6.9% were invasive, mainly belonging to neophytes. In the current period, an increase in invasive activity is recorded in another 5.3% of adventive (potentially invasive) species. The significant taxonomic and ecomorphic diversity of dendroflora in the coastal zones of the Northern steppe subzone of Ukraine is associated with ecotone effects, active processes of the territory urbanization, and the use of a wide range of alien ornamental species in public green spaces of cities. It is advisable to increase the share of autochthonic and rare species participation in the composition of coastal protective and recreational plantings, which will contribute to the preservation of their gene pool and increase the native dendrological diversity in the Dnipro river basin. To reduce the threats of phytoinvasions, it is necessary to: i) prohibit the use of invasive species in the restoration of native floodplain forests; ii) conduct a preliminary assessment of environmental risks from the use of alien species; iii) monitor existing plantings with their participation.