Abstract
Symphyotrichum squamatum (Spreng.) G.L.Nesom, a South American species, was first introduced to Europe in 1905 and has since become invasive in numerous countries. In Romania, it was first documented in Bucharest in 2015 and it has since spread to various urban and peri-urban areas. This study aims to assess the invasive potential of Symphyotrichum squamatum in Romania through a comprehensive approach that includes modeling the species’ potential distribution, evaluating its reproductive success, and analyzing morpho-structural characteristics of its vegetative body. Additionally, we compared the species’ traits with those of another alien species from the same genus, Symphyotrichum ciliatum (Ledeb.) G.L.Nesom, which is currently invasive in Romania, thereby demonstrating its potential for invasiveness. The potential distribution of both Symphyotrichum squamatum and Symphyotrichum ciliatum in Romania was modeled using the R software, with the SSDM package and environmental variables corresponding to the species’ ecological preferences, such as climatic variables, local topographic, pedological factors, and anthropogenic impact. Reproductive success of Symphyotrichum squamatum was assessed through germination tests on individuals from different populations. The modeling results suggested that Symphyotrichum squamatum’ distribution in Romania is largely influenced by the anthropogenic impact index and soil classes. Furthermore, the high percentages obtained from germination tests, along with the structural characteristics which highlighted its ability to adapt to a wide range of environmental conditions, indicate that Symphyotrichum squamatum is a species with expansion potential if it establishes under favorable environmental conditions, primarily represented by wetlands along watercourses and marshy areas.