World distribution: Ramalina obtusata occurs in the boreal regions of Europe and North America (Ahlner 1948, Ahti 1964, Krog 1968, Krog & James 1977, Thomson 1984). In Europe, the species is known from eastern Fennoscandia and the Central European mountains (Poelt 1969, Krog & James 1977, Wirth 1987, Nimis 1993). The species is widespread but scattered in Finland, most common in the eastern parts. In Sweden, it has a similar range as Ramalina dilacerata, but is much rarer (Krog & James 1977)
Ecology: Results. Indicated substrates are Picea abies (8), Alnus incana (1), Salix caprea (1), and Sorbus aucuparia (1). The main habitat was spruce forests (8); other recorded habitats were pine forest (1) and Alnus incana forest (1). All localities were situated near brooks, rivers, or lakes; 4 localities were situated in ravines or canyons. Discussion. The species is sometimes regarded as conspecific with R. baltica (see note). Ramalina obtusata s. str. grows on twigs of conifers, mainly Picea, occasionally on deciduous trees, and rarely on rock (Thomson 1984, Santesson 1993). I northern Fennoscandia, the species exclusively grows in spruce forests (Räsänen 1927, Ahlner 1948), often near waterfalls (Aronsson et al. 1995). In Central Europe, it occurs in humid montane forests (Wirth 1987, Nimis 1993). In North America, it often grows close to running water and lakes (Ahti 1964, Goward & Ahti 1992), frequently in localities with ample light (Goward & Ahti 1992). Ramalina obtusata is a possible indicator of long canopy continuity in Norway (Bredesen et al. 1993). The Norwegian localities may all be fire-free refugia
Threats: Results. The main threats recorded in the extant localities are forestry (1155), development of hydroelectric power (40, 1152), and local pollution from a mill (1152). Discussion. Collecting may have exterminated the species in two localities (1151, 1154) where Ahlner (1948) recorded single specimens. It has been repeatedly searched for in locality 1151 for 45 years, but in vain. Ramalina obtusata is regarded as a vulnerable species in Switzerland and endangered in Austria and the EU (Clerc et al. 1992). The main threat in Central Europe is commercial exploitation of natural forests, air pollution may also constitute a threat (Wirth 1976, Serusiaux 1989). In Sweden, it is regarded as vulnerable, threatened by hydroelectric development and forestry (Aronsson 1995). In Finland, it has declined strongly (Rassi & Väisänen 1987)
Status: All the seven old Norwegian localities were investigated, and the species was found in two (1152, 1155). In one locality (1154), the status was assumed to be uncertain, and the species is apparently extinct from 4 localities (35, 1151, 1153, 1156). One new locality was discovered (40). One extant (40) and one extinct (1151) locality are situated within nature reserves. A vigorous population on c. 20 trees was recorded in locality 40. This locality was very rich in rare species, e.g. Calicium lenticulare, Chaenothecopsis viridialba, Cybebe gracilenta, Evernia divaricata, Heterodermia speciosa, Menegazzia terebrata, Schismatomma pericleum, Sclerophora coniophaea, Ramalina dilacerata, R. sinensis, and R. thrausta. The rare fern Cystopteris sudetica also occurred at this locality (A. Blytt 1898, Berg 1993)
Notes: Some authors regards R. obtusata as conspecific with R. baltica (Degelius 1942, Ahlner 1948, Wade 1961, Ingelög et al. 1993).
Specimens in other herbaria, litterature, etc.