Alder dominated vegetation occurring in the shrub tundra belt along stream cutbanks and on north-facing slopes where moisture conditions are sufficient. Stands occur on all slope aspects but were always associated with bare rock or boulders and usually with abundant surface or subsurface water. Alnus crispa is also a pioneer on talus and glacial till where there is constant subsurface irrigation (Cooper 1986b). Entered by Jozef Sibik and Silvia Chasnikova. Edited by L. Druckenmiller.