This association occupies shallow depressions and habitats with impeded outflow of flood waters in the floodplains of the Dyje and Morava rivers in the dry region of southern Moravia. Spring floods may last for several weeks and the habitat remains wet for a rather long period after the flood water retreat. This favours moisture-demanding species, some of which are otherwise typical of tall-sedge stands. However, owing to the dry local climate soils dry out in late summer. Such conditions support the occurrence of several species with continental distribution. Inter-annual variation in moisture influences the proportions of different dominant species.