Ramalina thrausta (Ach.) Nyl.

Trådragg

World distribution: Ramalina thrausta has an incompletely circumboreal distribution, including Europe, Asia, and North America (Ahlner 1948, Thomson 1984). It is most frequent near the coasts and is not present in highly continental areas (Ahti 1977a). The species is scattered in the coniferous forests of central, eastern, and northern Europe (Ahlner 1948). In Fennoscandia it is widely distributed but nowhere common (Ahlner 1948, Krog & James 1977)

Ecology: Results. Indicated substrates include Picea abies (133), shaded vertical and/or overhanging lowland rocks (48), moss covered rocks in the alpine region (3), Sorbus aucuparia (2), decaying wood (1), Betula pubescens (1), and Juniperus communis (1). The habitat was recorded in 154 localities. Most records were from shaded spruce forests (142, often in brook ravines or close to rivers (85) or in east- to north-facing slopes or swampy forests (61)). More rarely it was recorded in canyons with mixed Pinus/Picea-forests (7) or with birch forests (2), and in alpine vegetation (3). In two localities it was growing in the spray zone of waterfalls. In Trøndelag noteworthy associates include Hypogymnia vittata, Lobaria pulmonaria, L. scrobiculata, Platismatia norvegica, and Pseudocyphellaria crocata, and in southeast Norway Bryoria bicolor, B. nadvornikiana, Cetrelia olivetorum, Hypogymnia bitteri, Menegazzia terebrata, and Usnea longissima. Discussion. Ramalina thrausta mainly grows on the lowermost branches of Picea abies in sheltered and humid forests, also see Ahlner (1948). It is considered as an indicator of long canopy continuity (Bredesen et al. 1993, Karström 1992, Olsson 1993), and seems to be mainly restricted to fire- and storm-free refugia. It is the dominant pendulous species in some humid spruce forests in Nord-Trøndelag; a phenomenon that is very rarely seen in northern Sweden (Karström et al. 1993). The species is not restricted to forests (Krog & James 1977) and ascends the timberline in moist and sheltered habitats and even occurs on coastal cliffs

Threats: Results. Recorded threats are forestry (91), development, including road construction (13), agricultural expansion (12), pollution (8), development of hydroelectric power (5), and ditching (1). Discussion. The species has declined dramatically the last decades, particularly in the coastal spruce forests of central Norway, mainly due to modern forestry. Populations growing on vertical rock walls in narrow canyons seem more able to survive. Epiphytic specimens were collected at several sites in southeast Norway by Ahlner in the 1940's, but now considered to be extinct from most. New observations in southeast Norway are mainly of saxicolous populations. The species is rare and/or threatened in Sweden (Hermansson 1990, Aronsson et al. 1995), Finland (Rassi et al. 1992), and the Alps (Türk & Wittmann 1986, Serusiaux 1989, Clerc et al. 1992, Nimis 1993)

Status: Seventy-four old localities were investigated. The species was still present in 19, although often as sparse populations, and assumed to be extinct from 47 localities, while the status was uncertain in 8. Forty-eight new localities has been discovered, mostly on vertical rocks in southeast Norway. Four localities (1131, 1996, 1998, 2617) are within protected areas

Specimens in other herbaria, litterature, etc.