A REVIEW OF LICHENS IN METAL-ENRICHED ENVIRONMENTS

The importance of mineralogy in determining lichen assemblages occurri ng on metalliferous rocks and derived soils is discussed with referenc e 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 s uggests 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 eith er metals within the substratum. A new lichen community, the Lecideion inopis Purvis, is described characterized by the faithful species Lec idea inops, Psilolechia leprosa and several Cu-rich ecotypes. This com munity occurs in alkaline environments where Cu is fixed predominantly as a secondary hydroxide or carbonate. Conversely, low pH, Fe sulphid e-rich environments, where Cu may also be present, are characterized b y the Acarosporion sinopicae, which includes several species with a ru sty 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 ult rabasic rocks, are also reviewed. Although mine spoil heaps and other mineralized environments are perceived in human terms as toxic, they m ay support a diversity of lichens, including rare taxa restricted to t hese sites. The systematic description of these lichen communities in relation to rock mineralogy and chemical processes are necessary if ph ysiological tolerance and speciation are to be understood. (C) 1996 Th e British Lichen Society