Letharia vulpina (L.) Hue

Ulvelav

World distribution: The species occurs in Europe, North Africa, Cyprus, the Caucasus, and western North America (Ahlner 1948, Gams 1955). The European distribution includes Fennoscandia and central Europe south to Spain and Italy (Schade 1954, Gams 1955). It avoids atlantic parts of Europe and is absent from the British Isles. Even though the species has a continental distribution in Scandinavia, the distribution shows an oceanic tendency at a world-wide scale. The species is particularly common in the Alps (Ahlner 1948). The Scandinavian distribution is mapped by Ahlner (1948). Letharia vulpina is extinct in Finland, and is not known from Denmark (cf. Alstrup & Søchting 1989). There are two centers of distribution in Sweden: one in northern Dalarne and southern Härjedalen (adjacent to the Norwegian center), and one in southern Sweden where it is restricted to human-made habitats like fenceposts and old, unpainted wooden houses (Degelius 1946b, Ahlner 1948). The species is now almost extinct in the southern center (Ingelög et al. 1984)

Ecology: Results. Letharia vulpina is in Norway mainly restricted to dead pine trees (54 records). In many cases no information was given as to whether the dead trees were decorticated or not, but dead wood was frequently mentioned as substrate. The species was also recorded from burnt wood (2). Standing dead trunks, as well as twigs and stumps of Pinus sylvestris were recorded as substrates. There were, however, also a few records from bark of living pine trees, from Picea abies (2), Betula sp. (2), Juniperus communis (1), and human made substrates like houses (3) and fence posts (1). Natural habitats were isolated, often dead trees in bogs (14), or old stands (14) with scattered trees near bogs or close to the timberline. Discussion. Letharia vulpina seems to be restricted to localities with long ecological continuity, and often grows on old trees. While other lichens of old-growth forest seemingly prefers more or less productive forests where they get some kind of shade or shelter, L. vulpina in Scandinavia thrives on wood even in sunny positions (Degelius 1946b, Ahlner 1948), also outside forests. The species is extremely photophilous (Barkman 1954, 1958), intolerant of canopy shade, and finds a niche in very open stands where waterlogged soils, nutrient-deficient soils and/or low temperatures limit growth and survival of trees. In other parts of Europe it normally grows on bark (Ahlner 1948, Gams 1955) and is confined to habitats with no direct radiation from the sun, but with ample diffuse blue skylight (Stoutesdijk & Barkman 1992: 127). The blue-shade adapted L. vulpina is expected to have its optimal habitats in areas with a prevailing clear sky at high altitudes. Letharia vulpina is intolerant of snow cover (Ahlner 1948, Barkman 1954), and is strongly frost resistant and highly acidophytic (Barkman 1958). Lange (1965) found that L. vulpina has a maximum CO2 uptake at only 7 °C, only slightly depressed at 0 °C, and still half the optimum at -5 °C. The species could therefore possibly be physiologically active also in milder periods during the cold season. Due to convectional cooling because of its relatively fine branches, L. vulpina thalli are not strongly heated even in dry condition (Kershaw 1983)

Threats: Results. Recorded threats were forestry (8) and cutting for firewood (5). Discussion. Ahlner (1948) stated that Letharia vulpina is probably the lichen species which is most sensitive to human disturbance. The species has its main occurrence in high-altitude Pinus sylvestris forests where low growth rates often limits commercial forestry. Forestry may destroy some localities by eliminating recruitment of the dead standing pine trees which are crucial for recolonization. Other threats are, however, probably more severe. Increase in recreational activities implies higher needs for dry firewood in remote areas. Ignorant tourists can easily cut down a good L. vulpina tree for the purpose of getting a cup of coffee. The species obviously also appeals aesthetically to man, and is sometimes used for decoration. The species is therefore one of few lichens for which collection represents a threat. Drainage of bog areas in the summer farm region for improving grass production for animal husbandry is another threat, as is a locally high elk population which may reduce or eliminate pine regeneration

Status: The number of known localities has increased considerably, from 32 to 120, since the previous Norwegian distribution map was published (Jørgensen & Ryvarden 1970). Despite the species was not given priority in the field work, as many as 22 new localities have been discovered since 1990. Only two old localities were visited, and intact populations were recorded in both. Most localities have a limited numbers of trees carrying the species, and a limited number of thalli on each tree. Populations seem to be rich and numerous only in two areas, Skjåk (3660) where it was recorded on some thousands of trees in a relatively continuous area of about 2 km2, and in the Femundsmarka National Park

Notes: There are two old records, in Nord-Trøndelag (2742, Schübeler 1886; no material available) and Finnmark (1431), respectively. These records are apparently the basis for including the two counties in the distribution of the species by Krog et al. (1980) and Santesson (1993). These records seem doubtful, and are rejected here..

Specimens in other herbaria, litterature, etc.