Investigation of Ecophysiological and Phytosociological Parameters on the Populations of the Invasive Alien Species Asclepias Syriaca l. In the Danube Valley, Romania

Asclepias syriaca L. commonly called common milkweed, butterfly flower, silkweed, silky swallow-wort, and Virginia silkweed ommon milkweed is a rapidly spreading invasive alien plant that threatens natural ecosystems, especially grasslands, but also some forest and agricultural ecosystems worldwide. This species is a flowering plant which can established viable populations across various regions. This study tries to evaluate the invasiveness of this specie in five localities from Oltenia region where, as a result of the observations made between March 2020 and September 2024, the presence of a large number of individuals was found. It was made determinations in 5 sites, located in the Danube basin in the south-western part of Romania. The size of the invasion with this species in the studied sites varies significantly, from a few individuals to a very large number. Phytosociological studies are essential to determine the presence, abundance-dominance and role of this species in invaded plant communities, in order to organize and manage management measures regarding the invasiveness of the species in the Danube Valley.Results on physiological responses such photosynthetic rate, intensity of transpiration and chlorophyll content varies with density and area. In all of the sites studied, A. syriaca fructifies well and produces viable seeds with a high degree of dissemination and very good germination capacity. Considering the rather large number of the individuals in the analyzed localities in south-west Romania, it can be expected a future spread and invasion in the areas. Thus, A. syriaca should be treated as an invasive species with high potential for aggressiveness on diversity because it can form dense colonies that suppress the growth of other species through competition for light, water and nutrients. Continuous monitoring and management strategies are essential to mitigate its impact on native biodiversity and ecosystem health in the context of climate change.