Boreal and arctic base-rich inland cliff

These are vegetated cliffs of calcareous and other base-rich rocks found in the boreal and arctic biogeographical regions, in Iceland, Svalbard, the North Sea Island groups of the Hebrides, Shetlands and Faroes, Fennoscandia, and further in northern Russia. As extensive limestone mountains are almost absent in Northern Europe, base-rich cliff habitats are confined to areas of igneous bedrock and, locally, dolomitic rocks or calcareous siltstone and beyond, though the habitat type has a circumpolar distribution in the northern Palaearctic, it is fragmented for geological reasons.  It does not include cliffs in the immediate sea spray zone (in B3.1a) or ultramafic cliffs (in H3.2e).

Boreal and arctic base-rich cliffs are important habitats for low-competitive bryophytes, lichens and specialist vascular plants and from a phytogeographic and evolutionary point of view the boreal mountains and the arctic share interesting relict Arctic-alpine plants with the Alps and the Carpathians. Nordic cliffs are poor in vascular plants but species of the genera Asplenium, Draba and Saxifraga may be gregarious in sheltered humid places, the latter especially in the alpine belt. Regional and altitudinal variation in species composition is high but among vascular plants, Asplenium viride, Woodsia glabella and Saxifraga nivalis may be regarded as characteristic for the base-rich boreal cliffs of northern and eastern Fennoscandia, although A. viride also occurs in ultrabasic cliffs.

The bryophyte component of the vegetation may be species-rich particularly in sun-averted crevices and on damp rock and is best developed in oceanic areas such as in southwestern Norway and Iceland. Numerous acrocarpous moss genera and hepatics are represented, among others Anoectangium, Didymodon, Encalypta, Grimmia, Gymnostomum, Gyroweisia, Leiocolea, Orthotrichum, Schistidium, Tortella, and Tortula and among the most abundant and widespread bryophytes are Distichium capillaceum, Ditrichum flexicaule, Encalypta streptocarpa and Tortella tortuosa. Exposed rock faces may be covered by crustose lichens (e.g. Acarospora, Caloplaca, Collema, Farnoldia, Thelidium, Polyblastia, Protoblastenia and Verrucaria) and other epilithic organisms.

Indicators of good quality

• Occurrence of rare species of bryophytes, lichens and phytogeographically significant vascular plants, 
• Presence of sizeable open exposed rock with species-rich bryophyte carpets and lichen crusts 
• Variety of aspects of rock walls, exposure to insolation, moisture and rock structures such as overhangs, cavities, rock shelters, ledges
• Contact with natural habitats such as screes, boulder fields and pioneer grasslands 
• Absence of quarrying and control structures 
• Absence of garbage dumping and anthropogenic nutrient input from above the cliff
• Absence of rock climbing facilities
• Absence of alien species

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats