The effects of physical-chemical water parameters on the Nymphaeion alliance development in northwestern Serbia
<em>Nymphaeion</em> alliance vegetation is dominant floating-leaved vegetation in the Danube–Tisza–Danube hydrosystem in northwestern Serbia and comprises <em>Nymphaeetum albae</em>, <em>Nymphaeetum albo-luteae</em>, <em>Nymphoidetum peltatae</em> and <em>Trapetum natantis</em> associations. Comparative analysis of physical-chemical water parameters on localities where these – in most parts of Europe endangered and vulnerable stands – develop showed that most phytocenoses are associated with specific habitat conditions. Of the analyzed water properties, the factors that cause <em>Nymphaeion</em> alliance phytocenoses differentiation are primarily pH, alkalinity and COD-MnO<sub>4</sub>. Formation of the <em>Nymphaeetum albae</em> stands is significantly associated with the highest values of pH, COD-MnO<sub>4</sub> and alkalinity, and the lowest nitrate, nitrite, dissolved and the total phosphorus content values, in comparison to the other studied associations. <em>Nymphoidetum peltatae</em> stands develop in waters characterized by the lowest pH and COD-MnO<sub>4</sub>, low alkalinity, and the highest nitrate and nitrite values in relation to the other analyzed phytocenoses. <em>Trapetum natantis</em> stands, on the other hand, prefer the warmer sections of the canal network, neutral pH, and the highest values of BOD<sub>5</sub>, dissolved and total phosphorus. Habitat conditions in which <em>Nymphaeetum albo-luteae</em> stands develop are of the widest range in comparison to other investigated phytocenoses.