Bare or sparsely vegetated streambeds and banks are distributed in all high mountain ranges and their foothills in temperate and boreal Europe. The habitat is highly dynamic due to periodical floods and a considerable variation in speed and intensity of the water current. The sediment includes mainly gravel deposits poor in organic material and nutrients. These gravel deposits are covered by sparse pioneer vegetation with several specialised plant species. Succession leads to willow scrub, but in the river systems with natural dynamics, the next flood causes disturbance of the shrubby stages and returns succession to an early stage. The habitat also includes periodically exposed gravelly shores of mountain lakes. Species composition of this habitat varies with elevation.