This vegetation type is formed of dense stands of Calamagrostis villosa which develop on sites of natural, montane spruce forests or mixed acidophilous spruce-fir-beech forests. In forest clearings and on sites deforested due to air pollution this vegetation may inhibit further succession of trees and form a long-term persisting successional stage. Artificial afforestation on these sites is difficult too. Soils are acidic and litter decomposition processes are slow. This vegetation type is common in the mountain ranges along the Czech borders at altitudes of 700–1100 m. It may occur in frost pockets at low altitudes as well.