Frequency of Occurrence and Level of Dominance of Alien and Native Species in Synanthropic Plant Communities of Southern Russia

摘要

In spite of stable interest of biologists in the problem of biological invasions, the role of alien dominants in the formation of vegetation in recipient regions has not yet been quantified. We compared the frequency of occurrence and levels of dominance of alien and native plant species in nine synanthropic vegetation sites located in the vicinity of several settlements in the Republic of Adygea and Krasnodar krai (Western Caucasus, including the basins of the Belaya, Tuapse, and Agoy rivers as well as the Kuban-Azov Lowland). Within each area, from 1950 to 3683 1-m(2) sample plots were laid (24 847 in total), on which the projective cover of dominant species was evaluated. The results showed that similar to 10% of dominants identified on the studied areas were alien species. Compared to native dominants, they were characterized by a slightly higher dominance frequency (per species) and the projective cover exceeding 80%. At the same time, alien plant species dominated on 2-28% of sample plots (12% on average), and their projective cover exceeded 80% only on 0.04-7.7% of sample plots (2.9% on average). In general, species similarity between the complexes of alien dominants from different sample plots was higher than that of native dominants. This means that the strengthening of positions of alien species leads to an increased homogeneity of synanthropic vegetation in southern Russia.