Phytosociological and Abiotic Factors Influencing the Coverage and Morphological Traits of the Invasive Alien Potentilla indica (Rosaceae) in Riparian Forests and Other Urban Habitats: A Case Study from Kraków, Southern Poland

Biological invasions are considered one of the most important threats to biodiversity worldwide, and their intensity increases with urbanization. Potentilla indica, a perennial stoloniferous plant of Asian origin, is a newly emerging invasive alien species in European cities and other areas. Due to its wide ecological range, it may threaten many native species, especially in urban riparian forests which are particularly susceptible to plant invasions. Although it shows high phenotypic plasticity, its coverage and morphological variability depending on the type of vegetation and abiotic factors in natural conditions have not been studied so far. Therefore, in this study, we aimed to explore this issue, using phytosociological relevés and measurements of selected environmental factors and morphological features of P. indica in Kraków, the second largest city in Poland, central Europe. We demonstrated that the coverage and morphological traits of P. indica can be significantly affected by the type of plant community, and the presence and abundance of the species in urban habitats are strongly related to soil moisture, electrical conductivity, and fertility. We also found that the coverage of P. indica is positively correlated with the Evenness index, height of herbaceous layer, soil electrical conductivity and moisture, and negatively with the number of species, soil compactness, and phosphorus content in the soil. We further revealed that the size of the leaves and the length of the pedicels and stolons in P. indica can be positively influenced by its coverage. To prevent the invasion of P. indica in riparian forests and other urban habitats, we suggest controlling its cultivation and disposal, removing new appearances, and maintaining high species diversity with a dominance of one or a few native species in plant communities.