World distribution: The species occurs in Europe, North America, northwestern Africa and New Zealand (Degelius 1954, 1974). In Europe it is scattered, but widely distributed, being known from the southern, central and western parts as far north as southern Fennoscandia (Degelius 1954, Nimis 1993). In Italy it is apparently not common (Nimis 1993) and in Germany it is extinct, endangered or vulnerable in several regions (cf. Scholz 1992). According to Seaward (1985: map 448) it is very rare in the British Isles with a few localities in southern England and one in Scotland. On the whole it seems to be rare in Europe. In Sweden it is known from about 15 localities in the southern part (Skåne to Västmanland; now extinct in all but one) and four localities in Lule Lappmark in the northern part (Arvidsson 1986, Aronsson et al. 1995). In Denmark it is endangered (Alstrup & Søchting 1989) and in Finland extinct (Rassi et al. 1992)
Ecology: Results. The species has been found on pollarded trunks of Ulmus glabra. The habitat was a grazed infield with old, pollarded, solitary elms in a slightly west-facing slope. Collema fragrans occurred on dry bark dominated by Gyalecta ulmi, and with Sclerophora nivea in somewhat dryer niches. Collema fragrans inhabited the SSW side of the trunks. Discussion. In Norway the species is so far only known from solitary, old, pollarded trunks of Ulmus glabra in the old cultural landscape of inner Sogn og Fjordane. In the British Isles the species occurs in similar habitats, being mainly restricted to nutrient-enriched bark of old trees of Ulmus in old parklands (Watson et al. 1988, Purvis & James 1992b). On a Scandinavian basis, the main substrate is Fagus sylvatica, Populus tremula and Ulmus (Ingelög et al. 1993), while it is more rarely found also on Fraxinus excelsior, Tilia cordata, and Betula (Degelius 1954). In southern Sweden it is found in the old agricultural landscape and on roadside trees in humid sites (Degelius 1954, Arvidsson 1986, Ingelög et al. 1993). In northern Sweden, it occurs on Populus tremula in spruce forests, often together with Collema curtisporum (Karström et al. 1993)
Threats: Results. Assumed was abandonment of pollarding (1). Discussion. The abandonment of pollarding, resulting in uprooting of trees by strong winds, is a major threat to the known population today. One fallen pollard was observed during the field investigation. Discussion. In England, Collema fragrans has decreased dramatically in recent years due to the demise of Ulmus (Purvis & James 1992b); spreading of the elm disease may thus represent a future threat also in Norway. Random extinction is also a threat for such small populations. In southern Sweden, the species is threatened by cutting of large trees and change in the use of old, grazed woodlands. The northern Swedish populations are threatened by forestry (Ingelög et al. 1993)
Status: Collema fragrans occurs sparsely on 4 elms at one locality. The site is not protected
Notes: The species is mentioned as a 'bonus species' for conservation status in the British Isles (Rose 1992)..
Specimens in other herbaria, litterature, etc.