Formalised classifi cation of the annual herb vegetation of wetlands (Isoëto Nano - Juncetea class) in the Czech Republic and Slovakia (Central Europe)

Vegetation of ephemeral wetlands (class Isoëto-Nano-Juncetea) was studied in the Czech Republic and Slovakia using a formalised classifi cation approach. We analysed a set of phytosociological relevés recorded in the study region comprising 17583 relevés of wetlands and some types of ruderal vegetation. Formal defi nitions of particular associations were completed using a dataset of 1580 relevés, originally assigned by their authors into the Isoëto-Nano-Juncetea class. 770 of these relevés were classifi ed into one of the three alliances (Verbenion supinae, Eleocharition ovatae and Radiolion linoidis) and nine associations: Ranunculetum lateriflori (south-eastern Slovakia), Cerastio-Ranunculetum sardoi (mainly southern Slovakia and southern Moravia), Veronico anagalloidis-Lythretum hyssopifoliae (southern Moravia), Pulicario vulgaris-Menthetum pulegioidis (southern parts of both republics, especially in Slovakia), Polygono-Eleocharitetum ovatae (mainly southern Bohemia and the Bohemian-Moravian Uplands in the Czech Republic), Cyperetum micheliani (both republics), Stellario uliginosae-Isolepidetum setaceae (mainly in southern Bohemia and Bohemian-Moravian Uplands in the Czech Republic, less frequently in Slovakia), Centunculo-Anthoceretum punctati (only two relevés in both republics) and Junco tenageiae-Radioletum linoidis (southern Bohemia in the Czech Republic, Borská lowland in western and Orava region in northern Slovakia). The main environmental gradient of the studied vegetation expressed by Ellenberg indicator values (EIV) is moisture (Spearman correlation coeffi cient with the fi rst DCA axes -0.666, p < 0.001), followed by light (-0.656, p < 0.001). Comparison of clusters based on EIV showed signifi cant differences in several cases, mainly: 1) the signifi cantly lowest EIV for temperature was detected for Stellario uliginosae-Isolepidetum setaceae and Junco tenageiae-Radioletum linoidis; 2) Polygono-Eleocharitetum ovatae had the highest EIV for moisture; and 3) Junco tenageiae-Radioletum linoidis had the lowest EIV for nutrients. Our study is one of the fi rst attempts at formal classifi cation of Isoëto-Nano-Juncetea vegetation in a relatively large area and to compare the ecology of the communities defi ned by this approach.