Temperate high-mountain siliceous inland cliff

Siliceous (rich in quartz and silicate minerals such as mica, feldspar, biotite and hornblende) cliffs and walls of acid rock in the high mountains of the nemoral biogeographical zone. The most common kinds of siliceous rock are granite, gneiss and crystal schist, mostly of Palaeozoic age. Younger igneous-volcanic acid rocks such as quartz-porphyry also occur, for instance in the western central Alps. As gneiss and granitic rocks weather more slowly than calcareous rock, the vegetation of vascular plants in crevices and on ledges in the high mountains is less species-rich. Siliceous rock-faces, on the other hand, are richer in epilithic lichens. Lichens of crustose (Acarospora, Haematomma, Lecanora, Lecidea s.l., Rhizocarpon, Sarcogyna, Schaereria, Sporastatia) and foliose (Parmelia s.l., Physcia, Umbilicaria) growth form prevail. Endolithic lichens and micro-algae are other important components of siliceous rock biota. Siliceous rock-dwelling bryophytes of the temperate high mountains include chiefly acrocarpic mosses and hepatics, among others many species of Grimmia, Racomitrium, Schistidium, Andreaea and Marsupella. Bryophyte diversity and abundance is highest in fissures of wet rocks and on ledges with a thin humus layer. Among the vascular plants tufted or matted perennial herbs prevail; plants of rosulate or succulent growth form may be prominent. Species-rich genera of silicolous chasmophytes are Saxifraga, Sempervivum, Primula, Phyteuma and Artemisia. Alpine siliceous cliffs are generally less species-rich than calcareous cliffs of the high mountains. Nevertheless, several range-restricted taxa are confined to siliceous inland cliffs.

The habitat type occurs in the high mountains of nemoral Europe, chiefly in the Pyrenees, the Alps, the Carpathians and the Balkanic mountain ranges of Stara Planina (Balkan range), Rila and Rhodopes, and further east in the Caucasus.

Indicators of good quality:

High-mountain siliceous cliffs of the temperate zone are particularly rich in lichens and bryophytes, less so in vascular plants. It is therefore advisable to take cryptogram diversity into consideration when assessing the habitat quality of siliceous cliffs. Relict arcto-alpine and range-restricted taxa among both phanerogams and cryptogams are the most significant biological quality indicators.

The following characteristics may be used as indicators of favourable quality:

• Occurrence of rare species of lichens, bryophytes and phytogeographically significant vascular plant taxa,
• Presence of sizable cliffs and large boulders with species-rich lichen crusts and bryophyte assemblages, with different aspects of rock-faces, different exposure, moisture and rock structures such as vertical rock faces, overhangs, cavities, rock shelters, and ledges
• Contact with natural habitats such as screes, boulder fields and alpine grasslands
• Absence of rock climbing facilities

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats