Calcareous and ultrabasic screes, with talus, boulder fields, glacier forefields, rock debris and riverine gravel banks, from the lowlands upwards to subnival levels in the eastern Mediterranean. Apart from epilithic bryophytes and lichens on rock outcrops and stable boulders, the vegetation consists mainly of specialist vascular plants adapted to the mobility of scree materials, the scarcity of fine-grained soil, mechanical disturbance, shortage of water and other physiological stresses. Towards the foothills and lowlands the habitat is rarer and more scattered but more prone to be affected by human disturbances, especially in terms of species composition. However, high mountain screes are usually well preserved, most within protected areas, and therefore in a very natural state.