Synanthropization and species diversityof floodplain ecosystems of the Ob-Irtysh basin, Russia

Currently, the phytocenoses of the Irtysh floodplain are experiencing intense anthropogenic pressures due to the intensive development of the oil and gas industry, as well as the urbanization of the territory. This paper focuses on the structure and species composition of the 27 studied areas in the floodplain ecosystems of the Ob-Irtysh basin. As a result of the research, we found 111 species of vascular plants from 33 families in plant communities. The areas belong to meadows and forest vegetation are represented by (1) birch forests (33%), (2) pine forests (10%), (3) fir forests (8%), (4) aspen forests (4%) and (5) associations of meadows (45%). Furthermore, we conducted a comparative analysis of the studied phytocenoses according to the Drude scale. To determine the anthropogenic transformation of the flora and individual plant communities, we determined the synanthropization index (the ratio of synanthropic species to the total number of species). In the synanthropic flora fraction, we distinguished 45 species belonging to 12 families, with the most multispecies being Apiaceae, Scrophulariaceae, Compositeae, Ranunculaceae, Poaceae, Fabaceae, Plantaginaceae. The synanthropization index of the studied phytocenoses ranges from 6.6% to 81.2%. The largest number of synanthropic species occurs in meadow associations, the content of synanthropes is greater than 50%, the structure is becoming more superficial, and the productivity and stability of plant communities are changing. The study of the horizontal structure of grass stands of meadow phytocenoses makes it possible to find the variability of different years, the change of dominant species and the stability of the species composition. Currently, researchers are paying considerable attention to the analysis of the structure of the herbage, since its study is of great theoretical and practical importance in clarifying phytocenotic relations.