Lobaria hallii (Tuck.) Zahlbr.

Fossenever

World distribution: The species is known from some scattered localities in western North America (Jordan 1973) and from one locality in southwest Greenland (Dahl 1950), as well as from Europe. In Europe, it is only known from Scandinavia (Ahlner 1948, Holien 1982). In Sweden, it is known from 11 localities, mainly by waterfalls, in Jämtland, Dalarne, and Lycksele Lappmark; it is still present in at least four of these (Aronsson et al. 1995)

Ecology: Results. Indicated substrates include Picea abies (8 records), Populus tremula (7), Sorbus aucuparia (6), Alnus incana (5), Salix caprea (1), Salix nigricans (1), Salix pentandra (1), and Ulmus glabra (1). Notably it has not been recorded on moss covered rocks in Norway. The habitat is indicated at 20 localities and includes swampy deciduous forests dominated by Alnus incana bordering brooks and rivers (7), brook ravines and northeast-facing slopes with spruce forest on marine sediments (7), the spray zone of waterfalls (4), broadleaved deciduous forest (1), and herb-rich birch forest (1). Discussion. According to Ahlner (1948), the species occurs in Scandinavia mainly on twigs of Picea abies in ravines with shaded spruce forest or in the spray zone of waterfalls. Field work during the last fifteen years indicates that the deciduous tree genera (Alnus, Populus, and Sorbus) are equally important as substrate. In one locality in Nord-Trøndelag (1611), hundreds of specimens covered the trunks of Alnus incana in a grove by a brook surrounded by an agricultural landscape. Unfortunately this locality was destroyed by agricultural expansion. A similar locality in Troms (231) has an even larger population which is still intact. Lobaria hallii shows a northern suboceanic distribution in Norway (cf. Flatberg et al. 1975)

Threats: Results. Recorded threats were forestry, by clearcut logging (10), agricultural expansion (2), and development of hydroelectric power (2). Discussion. At most of the localities the populations were sparse, often represented by less than ten, mostly juvenile individuals, per site. The only exception was one population on Alnus incana trunks in Troms (231). Populations on Picea abies were particularly small and are seriously threatened by forestry. The populations on deciduous trees are less subjected to pressure from human activity

Status: Twelve old localities were investigated. The species was present at 4 localities. In 5 localities it was assumed to be extinct and in 3 localities the status is uncertain. Five new localities have been discovered after 1990. One of the populations is possibly within a protected area (230, not investigated), and one (3556) will probably be proposed as a nature reserve (see Fylkesmannen i Nordland 1992)

Specimens in other herbaria, litterature, etc.