This association includes montane floodplain forests dominated by Alnus incana, in places with an admixture of Acer pseudoplatanus and Picea abies. The herb layer is species-rich and includes several species of tall forbs. Soils contain a large proportion of sand, gravel and stones. Floods are more frequent than in other types of floodplain forests but they are of shorter duration. In the Czech Republic this association occurs in higher mountain areas across the country.