Sparsely vegetated volcanic areas of Mediterranean and Macaronesian regions, comprising mostly recently deposited volcanic scoriae (tephra), lava flows or orifices in volcanic areas emitting hot gases and vapours in Italy and the Canary Islands. Intense solar radiation, remarkable daily temperature variations, long lasting snow-cover and mechanical disturbances caused by strong winds are usual conditions for this habitat type. Large areas are completely unvegetated or only covered by some lichens and mosses or a scattered and, on fragmentary soils, a discontinuous cover of a few, relic vascular plants.