Distribution and invasiveness of four non-native species of plants in ecosystems in the Chorokhi delta (SW Georgia)

Chorokhi Delta is known for its high diversity and many habitats, which however are being threatened by invasive plants. Here, the effects of four invasive species of plants, namely Ambrosia artemisiifolia, Sicyos angulatus, Solidago canadensis and Verbena brasiliensis were studied. These species were recorded in the coastal area of the Black Sea and in particular in Georgia for the first time in the first half of the last century and S. angulatus is a very recent arrival. Currently, these species constitute a significant threat to biodiversity at local, national and global levels. These invasive species were monitored from 2021 to 2022. During this period, sites with high densities of the invasive species were identified. For each species, 5 transects were randomly set, and along each of them, 10 plots (1 × 1 m) were surveyed. The density, frequency, coverage and average height of the invasive plants were measured in each plot. These measurements were recorded twice per year for two years (2021–2022). All this information will be used to develop management plans aimed at preventing their further spread or control their abundance. The results indicate that Ambrosia artemisiifolia is the most invasive and widely distributed. Verbena brasiliensis and Sicyos angulatus are also highly competitive species that can seriously affect semi-natural habitats in the Chorokhi Delta and in agricultural land located close to the Delta. Unlike these species, Solidago canadensis is not widely distributed in the area studied. However, its ability to survive in a wide range of habitats and clonal growth indicate that it is potentially a highly dangerous invasive species, which in the future is expected to expand its range and severely affect the semi-natural ecosystems and agricultural land in the Chorokhi Delta. The results of the present study demonstrate the high adaptability of the species studied and their potential for spreading further in the near future.