Alien plant invasion across coastal dunes of Ukraine

Coastal dunes are ecosystems significantly affected by the invasion of alien plants. The specific flora and plant communities across these habitats are currently under serious threat. The study was performed on shifting and stable dunes in Ukraine. We aimed to analyze (i) the alien species composition across Ukrainian coastal dunes, (ii) the division of alien plants by life forms, ecological requirements, introduction time, geographical origin, and naturalization degree; (iii) the distribution of alien plants in accordance with coastal zonation of sandy shores of the Black Sea and Azov Sea regions; (iv) which habitats are invaded more frequently.We found that in the flora of Ukrainian coastal dunes, 16.3% of species are alien; among them, 9.4% are neophytes. Most of them originated from the Mediterranean-Turanian region. Anisantha tectorum, Centaurea diffusa, Bromus squarrosus are the most frequent alien species. Regarding Raunkiaer's system of life forms, 61.6% of alien plants are therophytes. By the soil moisture, submesophytes (45.2%) are predominant. Ecological spectra according to soil acidity, nitrogen content, and salt regime of the soil showed that the alien plants distribution across Ukrainian coastal dunes are determined by the complex influence of different abiotic gradients. The highest number of aliens was observed on shifting dunes (19.3%). The stable dunes are less invaded (14.6%). The alien flora composition differs considerably across these types of dunes as well as across the Black Sea and Azov Sea coasts. Our results showed that the coastal dunes of Ukraine should be in the focus of conservation and management with the position of preventing biodiversity losses caused by alien plant species.