Degelia atlantica (Degel.) P. M. Jørg. & P. James

Kystblåfiltlav

World distribution: Degelia atlantica is an Atlantic-Mediterranean species (Jørgensen & James 1990). It is reported from Tunis, the Azores, Madeira, the Canary Island, Greece, the former Yugoslavia, Italy, Portugal, Spain, France, western parts of the British Isles, and Norway (map in Jørgensen 1978). It is, however, rare in the Mediterranean area where the specimens usually are poorly developed (Jørgensen 1978). In Fennoscandia the species is restricted to Norway. Large populations are only known in Scotland, Ireland and Norway

Ecology: Results. Degelia atlantica was collected on more or less moss covered rock walls (25 records), including one from calciferous and one from schistose rock, and on various broad-leaved trees: Populus tremula (7), Fraxinus excelsior (4), Acer platanoides (1), Tilia cordata (1), and Corylus avellana (1). Recorded aspects were western (6), northern (4), eastern (2), northeastern (2), northwestern (2), east-southeastern (1) and southeastern (1). The sites were in forest (10), pasture (1), heath (1), and scree (1). Discussion. Degelia atlantica seems mainly to be a saxicolous species in Norway, while it is mainly an epiphyte in the British Isles (Seaward & Hitch 1982) and further south (Jørgensen 1978). According to James et al. (1977), it occurs in a species-rich western facies of the 'Lobarion' alliance. Such vegetation has been recorded as locally abundant on moderately shaded, moss covered, broad-leaved trees in cool, sheltered, and continuously humid woodlands in the British Isles (Seaward & Hitch 1982). Degelia atlantica seemingly has a similar habitat preference in Norway, and the populations seem to occur in sites sheltered against strong sun exposure by topography and/or a tree canopy. The species is considered an indicator of ecological continuity in forests (Rose 1992)

Threats: Results. Recorded threats include logging and planting of Picea (5), building on the site (4), trampling (4), overgrowth (3), air pollution (1), and draining (1). Discussion. In parts of England the species has recently become extinct because of airborne acidic depositions (Farmer et al. 1992). It is likely to be threatened by any increase in air pollution and clearance of ancient woodland sites (Seaward & Hitch 1982)

Status: Twenty-four old sites were investigated. It was found in 8 sites, regarded as extinct in 9, and of uncertain status in 7. Nine new localities were discovered. In some sites it was abundant and luxurious, e.g. in 2229 and 2220. One locality is within a nature reserve (2639)

Notes: In Europe Degelia atlantica has its richest occurrences in Ireland and Scotland (Jørgensen, pers. comm. 1994); it is therefore referred to as a Fennoscandian responsibility species, although it is considered as vulnerable in the EU..

Specimens in other herbaria, litterature, etc.