Alien Species of Vascular Plants in the Flora of Prioksko-Terrasny Biosphere Reserve

The paper presents data on alien species of vascular plants in the Prioksko-Terrasny Biosphere Reserve. In total 96 species are classified as alien, which is 10,6% of the total floristic diversity. This proportion is small and reflects a low disturbance and relative stability of indigenous phytocenoses. The appearance of a new 43 alien species for the flora of the reserve was noted. The characteristics of the current state of populations of alien species, location and prospects for further development, are given. Almost all alien species registered by us (with the exception of Oxalis stricta, Torilis japonica, Conyza canadensis) to one degree or another are the result of introduction activities. Depending on the degree of naturalization and potential danger to the ecosystem, alien species are divided into 5 categories: Status 0 – cultivated (unnaturalized) (32 species); Status 1 – alien non-naturalizing plants (11 species); Status 2 – casual alien plants (2 species); Status 3 – naturalized plants (45 species); Status 4 – invasive species-transformers (6 species). Areas occupied by Cornus alba and Caragana arborescens have been measured to further estimate population growth by comparing with a similar measurement after several years. Extermination of small pioneer Heracleum sosnowskyi population is recommended.