Habitat conditions of nymphaeid associations in Poland

A comparative analysis of the habitats of seven nymphaeid associations: Pot amogetonetum natantis, Polygonetum natantis, Nuphar-Nymphaeetum albae, Nymp haeetum candidae, Nupharetum pumilae, Trapetum natantis and Nymphoidetum pe ltatae, was made within Poland. On the basis of water and substrate propert ies in the phytocoenoses analysed, it was demonstrated that most nymphaeid associations in Poland are distinctly associated with specific habitat cond itions. Trapetum natantis occurs in neutral waters, poor in NH4+, but marke dly rich in dissolved organic matter, K+, PO43-, total Fe and Ca2+. It deve lops best on slightly acidic mineral substrates poor in Ca2+ and Na+, but m arkedly rich in PO43- and NO3. Nymphoidetum peltatae occurs in alkaline wat ers with high concentrations of Na+, Cl- and NO3- and with relatively high concentrations of K+ and PO43-. Its substrates are mineral, poor in SO42- a nd total N and rich in NO3-, PO43- and K+. Nupharetum pumilae develops in w aters extremely poor in SO42-, Na+, K+ and Ca2+, but rich in NO3- and disso lved organic matter. It mainly occurs on organic substrates poor in Ca2+ an d Na+. Nymphaeetum candidae and Potamogetonetum natantis are mainly found i n mesotrophic waters. Polygonetum natantis mainly inhabits mineral substrat es poor in NO3-, Na+ and dissolved SiO2. Nupharo-Nymphaeetum albae occurs i n a wide range of most types of habitat.