Temperate, lowland to montane siliceous scree

Siliceous (acidic) screes and moraines of warm exposures on the lower slopes of mountain ranges of the nemoral zone, including the Alps, Pyrenees and Hercynian ranges, also on hills and lowlands and, locally, of middle European upland or lowland sites. They consist of various volcanic, crystalline, metamorphic or sedimentary rocks with acidic to neutral reaction. Often the screes are mixed with fine soil. The vegetation can completely lack, but in other sites is represented by forb- or fern-dominated, sometimes by moss- or lichen-dominated, species-poor communities. Siliceous screes in general have a lower species richness than calcareous screes. But the diversity of fern species is higher than in calcareous screes. Examples of characteristic ferns are Cryptogramma crispa, Dryopteris oreades and Dryopteris expansa. The screes on warm slopes of the subalpine level of the Alps and the Pyrenees, usually composed largely of big stones or boulders, are occupied by communities of Senecio leucophyllus, Taraxacum pyrenaicum, Galeopsis pyrenaica, Xatardia scabra, Armeria alpina. In central Europe and the Carpathian’s periphery screes are often dominated by Achnatherum calamagrostis, Melica ciliata and Galeopsis ladanum. Similar communities can also occur on secondary substrates, like in quarries, but they must not be treated as the habitat. Screes have a very special cold microclimate and are often inhabited by invertebrate glacial relict species.

Indicators of quality:
•    occurrence of natural erosion processes,
•    presence of rare, relict or endemic species,
•    absence of human activities, incl. grazing,
•    absence of alien species (e.g. Robinia pseudacacia may support the processes of stabilisation of screes and extinction of the typical flora).

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats