This association occurs in the most calcium-rich fens in the Hercynian part of the Czech Republic, which are located in the Cretaceous bedrock area of central Bohemia. Tussocks of Schoenus.ferrugineus or S. nigricans dominate the vegetation. Short sedges and other fen specialists grow between the tussocks. The moss layer is species-poor or absent. The vegetation tends to be stressed by phosphorus and iron deficiency, high salt content and fluctuating water regime with seasonal desiccation of the upper soil layers.