Mediterranean siliceous inland cliff

Siliceous (rich in quartz and silicate minerals, such as feldspar or mica) rock walls and cliffs in the Mediterranean, with cliff-dwelling vascular plants (chasmophytes), bryophytes, lichens, epi- and endolithic micro-organisms. Siliceous cliffs chiefly consist of igneous rocks, such as granite, diorite and andesite, or of metamorphic rocks, such as gneiss, slate, schist and quartzite. The ability of plants to root in siliceous cliffs depends on the rock texture, schistosity, moisture content and chemistry. Perennial herbs prevail, many as cushion or rosulate plants, some are succulent. Other common chasmophytes are dwarf shrubs and small ferns. Well represented genera of vascular plants in siliceous inland cliffs all over the Mediterranean are Asplenium, Hieracium and Saxifraga.

Siliceous inland cliffs are less common in the Mediterranean than calcareous cliffs but also rich in rare and/or endemic plants. Plant communities are numerous and, like many of their species, frequently restricted to a single mountain range, larger islands or cliff systems. Overall variation in species composition follows chiefly phyto-geographical patterns and reflects evolutionary history.  Local variations are typically due to the rock type, exposition, moisture and cliff height. Many species are poor dispersers and plant communities require long time to establish. Most of the characteristic species are not found in anthropogenic habitats, such as walls.

Mediterranean siliceous inland cliffs occur in the western, southern, central and eastern parts of the Iberian peninsula, southern France, Corsica, Sardinia, Sicily, southern Italy, Albania, Greece, a few Aegean islands (e.g. Samothraki), and Mediterranean Turkey. Included are all levels from the Mediterranean coastal areas to the high mountains.

Indicators of quality:

Mediterranean siliceous inland cliffs harbour many local and regional endemics. Populations of such species indicate high habitat quality. As there is much regional variation in chasmophytic vegetation and species richness the habitat quality of a local cliff or cliff system must be seen in relation to the regional chasmophytic species pool: the higher the proportion, the better the quality. Cliff habitats are naturally protected due to their poor accessibility but they may be destroyed through rock control structures and quarrying. Abandoned siliceous quarries are generally, even after decades, much poorer in species and lower habitat quality compared to the natural cliffs.

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

• Occurrence of a representative set of rare species, in particular narrow or regional endemics

• Presence of different aspects of rock walls, 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, rock shrubs and pioneer grasslands

• Absence of quarrying and control structures

• Absence of garbage dumping and nutrient input from above the cliff

• Absence of rock climbing facilities

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats