The phytocoenology, distribution, and habitat preferences of the species Aldrovanda vesiculosa (Droseraceae) in Romania

Aldrovanda vesiculosa is an endangered aquatic species in Romania which grows in shallow waters where competition with other aquatic species is limited or absent. A comprehensive overview of the species’ distribution and habitat preferences in Romania is currently lacking. In this context, this study aimed to update the distribution and habitat preferences of the species. Localities from Dobrogea, Oltenia, Muntenia, Transylvania, and Crișana represented the study areas. For the vegetation classification, 71 releves with A. vesiculosa were analysed. The size of the sample areas ranged from 4 m2 to 25 m2. Vegetation syntaxonomic assignment was performed by agglomerative hierarchical clustering. The optimal number of clusters was chosen using the corrected Rand and Silhouette indices. Diagnostic species were identified for each cluster based on the indicator value index (IndVal). The study results showed that the dominant majority of the previous populations of A. vesiculosa (89%) were no longer identified from Romania in the 2008‒2021 period. Recently (2021‒2023), they were found only in six localities in the Dobrogea, Transylvania, and Oltenia regions. The causes of the disappearance of the species are eutrophication and the lowering of the water level. From a phytocoenological point of view, 11 plant communities were identified where A. vesiculosa is found. According to the EUNIS classification, this species inhabits wetlands (Q) and inland surface waters (C). In conclusion, translocation is suggested as the primary conservation measure for protecting the species.