Seasonal dynamics of a periodically flooded man-made habitat in a submontane region: Junco bufonii-Gnaphalietum uliginosi or Cyperetum micheliani?

As a result of water regulation in the past, periodically exposed natural habitats with vegetation of the class Isoeeto-Nanojuncetea in Slovakia and the surrounding Central European countries have recently become scattered. Many of its characteristic species have, however, found opportunities for living in secondary habitats such as water reservoirs or field depressions. While much research has been carried out on amphibious vegetation in Slovakia, no data drawn from the Liptov Basin have been published to date. Here we provide the first vegetation survey of exposed banks of the Liptovska Mara Dam, four decades after its construction. Vegetation analyses identified three groups. Cluster 1 gathered on regularly exposed banks with nitrophilous perennial vegetation (Bidenti-Polygonetum hydropiperis and Rumici crispi-Agrostietum stoloniferae). Cluster 2 was found in the middle zone formed by annual stands and was the most widespread vegetation type within the studied object. In the newest surveys from the Czech Republic and Slovakia, vegetation with the same species composition was reported as Cyperetum micheliani. Comparison of those data with ours revealed that stands from Liptovska Mara belonged to the association Junco bufonii-Gnaphalietum uliginosi. Finally, cluster 3 grouped the most rarely exposed shores, with dwarf annual vegetation blocked by repeating inundation (Eleocharito acicularis-Limoselletum aquaticae). The length of flooding, slope and soil texture were the primary factors affecting the zonation of plant communities. Despite the secondary origin of the study object, the species composition is natural, and spreading of neophytes was not detected. In the case of such an artificial habitat, this is a remarkable finding.