Species and structural diversity of flora and avifauna on the territory of urban water treatment facilities

Background. The territories of urban wastewater treatment facilities, where the natural vegetation has been radically changed to synanthropic vegetation, promote the spread of ruderal plant species, including invasive ones, but at the same time create a favourable environment for nesting and staying of many bird species, including rare and those listed in the Red Data Book of Ukraine. The aim of this study is to investigate the species and structural diversity of vegetation on the territory of urban wastewater treatment facilities in order to determine their significance for the conservation of avifauna. Materials and Methods. To analyse the state of biodiversity, an inventory of species of higher plant and avifauna in the technogenic areas of Kharkiv wastewater treatment facilities in the spring and summer of 2020–2021 was carried out using conventional methods. Results. The flora of higher vascular plants includes 90 species belonging to 78 genera, 30 families, and 2 classes of the Magnoliophyta division. The leading families are: Asteraceae (30.0 %; n = 90), Poaceae (12.2 %), Brassicaceae (6.7 %), Fabaceae and Polygonaceae (4.4 % each). Herbaceous plant species (92.0 %; n = 90) dominated according to the С. Raunkiær classification (1934), with a predominance of hemicryptophytes (54.0 %) and terophytes (37.0 %). The increased proportion of the latter, compared to the zonal flora, indicates a significant disturbance of the habitat by anthropogenic factors. This is also evidenced by the predominance of synanthropic plant species (81.1 %; n = 90), including 40 species (54.8 %; n = 73) belonging to the apophyte group, and the remaining 45.2 % are adventitious species. In relation to moisture, most plants are mesophytes (71.0%; n = 90). In terms of geographical structure, the flora has a Holarctic-European-Eurasian character with admixtures of North American, Mediterranean, Nomadic and Mediterranean-Asian geoelements. The avifauna includes 95 species belonging to 13 orders and 29 families. Birds of Passeriformes (32.6 %), Charadriiformes (24.2 %) and Anseriformes (13.7 %) predominate. The treatment facilities are important for nesting of 53 species (55.8 %; n = 95), and are also a trophic base for 23 (24.2 %) of wandering and 19 (20.0 %) of transient bird species. The nine faunal groups were dominated by boreal 26.6 % (n = 95) and tropical 13.8 %, as well as limnophilous (12.8 %) and nemoral (11.7 %) species. The nesting avifauna was formed mainly by nemoral 17.0 % (n = 53) and tropical 15.1 %, as well as alluviophilous and boreal (13.2 % each) species. The greatest bird diversity is found in the overgrown silt areas, where vegetation with a projected cover of 50–70 % is interspersed with shallow water as close as possible to natural areas. Among the identified bird species, the following breeding birds are listed in the Red Data Book of Ukraine: Himantopus himantopus, also transient and wandering species: Milvus migrans, Hieraaetus pennatus, Columba oenas. Conclusion. The established plant communities with rich avifauna, including rare bird species, and the location of the treatment facilities within their migration routes, indicate the importance of these areas for the conservation of biota.