This subalpine grassland, dominated by Calamagrostis arundinacea, occurs in the glacial cirques of the Krkonoše and Hrubý Jeseník Mountains. It is confined to well-insolated steep slopes with pronounced winter snow accumulation which thaws rather early in spring and does not delay the advent of the growing season. The altitudes supporting this vegetation mainly correspond to the upper part of the forest belt, but in the habitats of Calamagrostis arundinacea trees are excluded by avalanche disturbance. The favourable temperature regime supports the occurrence of some herbs typical of deciduous forests, but species of the alpine belt are also present. This peculiar mixture of species of different origins fosters the exceptional species richness, which is higher than in other natural grassland communities of the subalpine or alpine belt in the Czech mountains.