Invasion Levels of Alien Plants in Various Habitat Types in the Middle Urals

The purpose of the study was to estimate invasion levels of alien plants in various natural and anthropogenic habitats of the Middle Urals in two urbanization manifestation variants: (1) within the boundaries of a large city; and (2) in suburban areas. In total, 965 geobotanical relevés produced in natural (bogs, floodplains, petrophytic areas, meadows, and forests) and anthropogenic (wastelands, public gardens, and residential areas) habitats were analyzed. Natural habitats were surveyed within the boundaries of a large city and in its suburban zone (at distances of 30–40 km from the city). Invasion levels were determined based on the number and proportion of alien (adventitious) species in the description. Both in suburban and urban conditions, the lowest numbers of alien species were recorded in bog habitats (on average, 0–0.6 species per description); while the largest numbers, in anthropogenic habitats (on average, 9.8–17.6 species per description). Outside the city, average numbers of alien species in natural habitats (except for bogs) varied in the range of 1.0–2.8 species per description; within the city, 3.8–6.2 species per description. In natural habitats (except for bogs), average shares of alien species varied in the range of 1.8–5.6% outside the city and in the range of 8.1–16.2% within the city; in anthropogenic habitats, they varied in the range of 22.8–32.8%. Suburban and urban wastelands did not differ in numbers and proportions of alien species (10.3 and 12.9 species per description and 25.3 and 30.2%, respectively). Invasion levels identified in suburban areas are consistent with those recorded in Europe.