Habitat variability and classification of Utricularia communities: comparison of peat depressions in Slovakia and the Třeboň basin.

Vegetation with species of Utricularia and that dominated by Eleocharis quinqueflora, which occupy the same habitats. was studied in minerotrophic mires and oligotrophic wetlands associated with ponds. Relative towater and soil chemistry, the communities of Utricularia ochroleuca s.l. and U. intermedia occurred in mineral-poor and those of U. minor and U. australis in mineral-rich conditions. Rare stands with U. vulgaris occurred in conditions that were intermediate in mineral richness. Four communities belonging to the class Isoëto-Littorelletea were distinguished. Vegetation without bladderworts and dominated by E. quinqueflora occurs in calcareous fens and belongs to the class Scheuchzerio-Caricetea fuscae (the Caricion davallianae alliance). Vegetation with U. intermedia is characterized by high vascular plant cover and belongs to the class Scheuchzerio-Caricetea fuscae. Utricularia ochroleuca s.l. prefers open, acidic and waterlogged depressions in peat, whereas U. intermedia grows mostly in the shade under vegetation canopy. In this study, U. minor and U. australis have been found mainly in the more alkaline and mineral-rich habitats, and both species also tolerated extremely high mineral richness.