Heterodermia speciosa (Wulfen) Trevis.

Elfenbenslav

World distribution: Heterodermia speciosa is a cosmopolite, distributed from the tropics to the boreal region (Kurokawa 1962 (including Anaptychia pseudospeciosa var. tremulans), Swinscow & Krog 1976, Swinscow & Krog 1988). In Europe, the species occurs in continental parts of Fennoscandia and in suboceanic parts of Western and Central Europe (Schauer 1965, Ingelög et al. 1987, Nimis 1993). It is scattered, but rare throughout Sweden (Ingelög et al. 1987), and is known from a few sites in the southeastern part of Finland (Hakulinen 1962)

Ecology: Results. The species is mainly muscicolous and occurs on sheltered, steep rocks or boulders facing north or northeast (46 localities). It was recorded once on trunks of Populus tremula and once on Betula sp. Most records were from boreal deciduous woodlands: Alnus incana forests (14), Betula forests (11) and unspecified deciduous forests (6). There were also records from Picea forests (4), Pinus forests (4), mixed or unspecified coniferous forests (2). The species rarely grows on exposed boulders (2). Eighteen localities were situated near rivers, brooks or lakes. Associated macrolichens recorded in saxicolous habitats included Cetrelia olivetorum, Evernia mesomorpha, Lobaria pulmonaria, L. scrobiculata, Pannaria conoplea, and Physcia spp. Discussion. Heterodermia speciosa normally grows under some shelter from trees, but avoids deep shade. In Fennoscandia, the species requires open forests in steep hills and screes, where the species is saxicolous on sheltered and moss covered rocks, often of calciferous schist (Hakulinen 1962, Ingelög et al. 1987, Rassi & Väisänen 1987). In the traditional agricultural landscape of Gudbrandsdalen, the species mainly grows on large boulders in weakly grazed woodlands with Betula spp. and Alnus incana. Probable primary localities are situated in screes. Primeval forests may also have been primary habitats, as has been postulated for some other species in the traditional agricultural landscape (cf. S.G. Nilsson et al. 1994). Heterodermia speciosa seems to indicate habitats with several rare lichens, like Cetrelia olivetorum and Menegazzia terebrata. In Central Europe, the species is mainly corticolous, and described as occurring in 'Lobarion' communities of ancient montane forests by Frey (1963), Wirth (1987), and Nimis (1993). The southernmost locality in Norway (2102) conforms to this description; here H. speciosa grows on a Populus tremula trunk with well-developed Lobaria pulmonaria. However, it has also been reported from moss covered rocks (Frey 1963) in Central Europe

Threats: Results. Recorded threats are logging (26), overgrowth (14), construction (11), development of hydroelectric power (7), forest plantation (2), agricultural expansion (2), collection (2), and pollution (2). Discussion. The species is often threatened by a combination of the mentioned effects. Grazing by domestic animals in boreal deciduous forests has declined dramatically, resulting in overgrowth and a too shaded environment for H. speciosa. As a consequence lichens are often overgrown by mosses. Sometimes the forests are converted into dense Picea abies plantations. In coniferous forests, H. speciosa is apparently vulnerable to clear felling. However, the decline of the species in continental valleys is mainly due to changes in the traditional agricultural landscape. In Sweden, the species is threatened mainly by forestry (Aronsson et al. 1995). In Finland, the decline is mainly due to forest plantations and pollution (Rassi & Väisänen 1987). The species is also considered to be threatened in Central Europe (Clerc et al. 1992)

Status: Twenty-seven old localities were investigated; among these the species was found in 7, apparently extinct in 17, and of uncertain status in 3. Thirteen new localities were discovered. The species occurred very scantily in 12 of the investigated localities. Rich populations with many individuals on several rocks or boulders were observed in three localities only. The following localities are protected within nature reserves: 929 (probably), 2102, and 2125, but none are ample

Specimens in other herbaria, litterature, etc.