Сomparative analysis of the species abundance and structure of plant communities involving <i>Rhamnus cathartica</i> in Belarus and in the midwestern regions of the USA

The history of intentional introduction of Rhamnus cathartica L. into the Midwestern regions of the USA is briefly described. The species abundance and structure of plant communities, in which Rhamnus cathartica, a native species for Belarus and invasive in the USA grows, has been studied. We compared the studied parameters (floristic description of the monitoring plots, field enumeration of Rhamnus cathartica individuals, average height, projective coverage of the accompanying herb species) at two permanent sample plots in Belarus and three permanent sample plots in the Midwestern regions of the USA. The data confirmed the hypothesis of increased competitiveness of non-native species in the secondary range (EICA). In American populations, compared to Belarusian populations, Rhamnus cathartica has larger sizes, higher seed production, higher number of juvenile individuals, and higher total number of individuals in the population up to the formation of single-species thickets. Invading Rhamnus cathartica into natural plant communities in the USA reduces the number of herbaceous species 8 times! As control measures, the Minnesota Arboretum has begun balding the areas invaded by Rhamnus cathartica, removing juvenile plants (one to five years old) and replanting native tree species.