Phytosociology, ecology, and distribution of Gymnospermium odessanum in Romania

Background and aims – Gymnospermium odessanum is a threatened plant species whose presence ranges from south to south-east in Romania. In this context, the study aims to ecological conditions and update the species distribution and identify the plant associations in which the species occurs. Material and methods – The species’ distribution was investigated for all the populations mentioned in the literature and other potential locations. Phytosociological relevés were collected in all locations in which the species is present. We applied Agglomerative Hierarchical Clustering to compare the species composition of the plant communities and to identify the main clusters, which we assigned to phytosociological associations and EUNIS habitats. We compared environmental conditions among the identified vegetation units. Key results – The numerical analysis revealed five well-defined vegetation units, identified to five known associations. The associations in which G. odessanum was the most abundant were Artemisio austriacae-Poetum bulbosae and Gymnospermio odessani-Celtetum glabratae. The total number of individuals recorded in all locations is approximately 1107, with a density of 10 to 200 individuals/100 m2. Compared to the observations made in 2007 (2135 individuals), the number of individuals has decreased. The area occupied by the population tended to decrease as well. The population’s conservation status and changes in the range pattern of the habitat type are unfavourable-inadequate. Conclusion – In the two associations in which it was the most abundant, G. odessanum is limited to some locations in Dobrogea, where the occupied areas have been significantly reduced due to habitat fragmentation and anthropogenic impact, including overgrazing.