Low-altitudinal siliceous and base-rich screes: new habitats to Bulgaria from the Habitats Directive

The study presents recent data on the distribution of two new chasmophytic habitats to Bulgaria. They are low-altitudinal siliceous screes distributed mostly in South Bulgaria, and calcareous screes found mostly in the northern part of the country. Their main characteristics, as well as many typical vascular plants, mosses and lichens are given in the paper. The habitats are included in the Habitats Directive under the names 8150 Medio-European upland siliceous screes and 8160* Medio-European calcareous screes at hill and montane levels. This was the reason to make an attempt at calculating their representativeness in the existing NATURA 2000 sites in Bulgaria by means of field researches, GIS models from the Forestry Database and mapping.