Alien plant species in national parks from Romania

In order to fulfill the obligations arising from Regulation 1143/2014, Romania carried out an extensive inventory process of invasive alien species throughout its territory between 2020 and 2022 within the POIM 2014+ 120008 project. In this context, special attention has been paid to protected natural areas (national and natural parks, Natura 2000 sites, nature reserves, etc.). In this study, we aim to analyze the distribution of alien plant species in the 13 national parks in Romania and in the Danube Delta Biosphere Reserve in order to better understand the factors that favor their presence in protected natural areas. For some of the national parks, no alien plant species were reported during the project (e.g. Buila-Vânturarița, Călimani, etc.), but their presence is confirmed by previous reports. In the case of other national parks, only a few alien plant species have been reported (1-5). This situation can be explained by the limited anthropogenic activity within the perimeter of the respective parks, by the lack of significant traffic roads in the vicinity, by the high altitude at which the parks are located. Instead, most species have been identified in the Danube Delta Biosphere Reserve, including a few that fall under Regulation 1143/2014. The large number of alien species in the Danube Delta is favored mainly by the water which is a very good vector for most propagules, but also by the anthropogenic activities specific to the localities in the Danube Delta. Also, the national parks crossed by important roads, but also by large rivers have an increased number of alien species (e.g. the Defileul Jiului National Park). Of the species of concern for the EU, the following have been inventoried in the national parks: Ailanthus altissima , Elodea nutallii , Impatiens glandulifera , Reynoutria japonica , Reynoutria × bohemica . In conclusion, alien plant species are poorly represented in most national parks, but they are becoming more common in areas with anthropogenic influence and high connectivity, such as the Danube Delta, which highlights the need for priority monitoring and management in these areas.