Over the last century, the distribution of Teloschistes flavicans has contracted from being widespread in the southern half of England and Wales to being limited to South-West England with outlying populations in Pembrokeshire and North Wales. Twelve core sites have been identified where the species is well established: ten of these are saxicolous/terricolous habitats on windy coastal cliff tops; the other two are lines of sycamore trees near the coast. At 39 further localities, some inland, the species is in very small amounts (often on one tree) and vulnerable to extinction. It is normally a member of the Parmelietum revolutae or Ramalinetum scopularis associations. The conservation of the species is discussed.

Three species are recognized as additions to the British montane lichen flora: Catillaria gilbertii sp. nov., Halecania bryophila sp. nov., and H. micacea sp. nov. All three have so far been recorded only from the mica-schist mountains of the Central Highlands of Scotland.

The new combination Stereocaulon plicatile (Leight.) Fryday & Coppins is made for a previously enigmatic crustose lichen with submuriform ascospores; the basionym, Lecidea plicatilis Leight., was previously misapplied to a norsticticacid containing species of Rhizocarpon. The systematic position of the crustose Stereocaulon leucophaeopsis group is discussed.

The lichen vegetation associated with calcareous rocks, areas of long snow-lie and the margins of high-level lakes in North Wales is described. It includes Porpidia ochrolemma (Vain.) Brodo & R. Sant. and Rhizocarpon anaperum (Vain.) Vain, new to the British Isles, plus a further 30 taxa recorded for the first time from Wales. The relative importance of the montane lichen vegetation of North Wales is assessed by comparison with areas in other parts of the British Isles. It is shown to exceed in interest any montane area in England or Ireland but to be below the standard of an otherwise comparable area in Scotland.

Skomer Island, a National Nature Reserve, lies off the West coast of Wales. This small island holds lichen communities of international importance associated with large populations of seabirds. Saxicolous lichen communities are described, 248 species listed and details given of a base-line monitoring programme, which will provide data on changes in the lichen flora over time and distinguish cyclical from permanent deleterious changes. Threats to island populations are discussed, such as the likely effects of oil pollution following the Sea Empress accident in February 1996.

The importance of mineralogy in determining lichen assemblages occurring on metalliferous rocks and derived soils is discussed with reference to environments enriched in metals from mine and smelter wastes and other sites involving human activities. A study of lichens growing on Cu and Fe sulphide-rich rocks in Scandinavia is presented. This data suggests that the composition of the lichen communities is governed by mineralogy, which influences the mobility and availability of Cu2+ and Fe2+ in the environment, rather than the total concentrations of either metals within the substratum. A new lichen community, the Lecideion inopis Purvis, is described characterized by the faithful species Lecidea inops, Psilolechia leprosa and several Cu-rich ecotypes. This community occurs alkaline environments where Cu is fixed predominantly as a secondary hydroxide or carbonate. Conversely, low pH, Fe sulphide-rich environments, where Cu may also be present, are characterized by the Acarosporion sinopicae, which includes several species with a rusty colouration. Contrasting assemblages rich in terricolous ephemeral species, especially Vezdaea spp. occurring in Pb/Zn-rich environments, and the comparatively species-poor assemblages on Cr and Ni-rich ultrabasic rocks, are also reviewed. Although mine spoil heaps and other mineralized environments are perceived in human terms as toxic, they may support a diversity of lichens, including rare taxa restricted to these sites. The systematic description of these lichen communities in relation to rock mineralogy and chemical processes are necessary if physiological tolerance and speciation are to be understood.