Trends in major ionic components of bulk precipitation were analysed for two sites, Faskally and Loch Ard forest in Scotland, for the period 1972-2000. The pattern of change was not linear. Large reductions in sulphur deposition occurred in the early 1980s and, to a lesser extent, during 1995-2000, with a period of relative stability between 1988-95. pH increased significantly at both sites but nitrate and ammonia only increased significantly at Loch Ard forest. Long-term chemical data from a total of 37 streams and lochs in four selected regions of Scotland were analysed over three time periods (all available data (mostly 1978-2000), 1988-98 and 1995-2000) to match the deposition patterns. For the whole study period a significant decline in non-marine sulphate was found at all sites while the most consistent increases in pH and alkalinity were recorded at all the high elevation loch sites in the Galloway area. Significant reductions in toxic forms of aluminium were also recorded, mostly at sites where pH had increased. Nitrate trends were equivocal except for catchments with clear-felling operations. For these sites, negative trends were found where felling occurred in the 1980s, while positive trends were found at sites with felling in the 1990s. With the exception of one site, dissolved organic carbon concentrations increased significantly with moorland sites showing smaller increases than forested sites. Associated with this change was a significant increase in complexed forms of aluminium. Trends for the 1988-98 period were much smaller than those for the whole study period and in many cases were insignificant. This contrasts with the 1995-2000 period when large and significant reductions in sulphate and nitrate were recorded along with increases in marine salts, probably as a result of climatically related events. Qualitative, experimental and monitoring data from lochs in the Galloway area revealed evidence of recovery of fish populations. Interpretation of chemical and biological trends was clearly influenced by the choice of the time series, especially in relation to deposition and climatic changes. Nevertheless, all the fresh waters included in this study are currently in the best ecological condition since the 1970s in the context of recovery from acidification.

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In the search for cost-effective methods for measuring and monitoring lichen diversity, we tested the performance of two possible indicators: lichen genus diversity and macrolichen diversity. We studied the lichen vegetation of eight European countries situated in six different biogeographic regions. In each country, six land-use units (each 1 km 2 ) representing a land-use gradient ranging from old-growth forest to farmland were sampled (n = 48) for terricolous, saxicolous, and epiphytic lichens at 16 plots each. We found 768 different lichen species belonging to 157 genera. Relationships between richness and density of genera and species, species and macrolichens, and crustose lichens and macrolichens were highly significant (p < 0.001) for all substrates combined and for epiphytic and saxicolous lichens. Richness and density of genera and macrolichens explained a large amount of variation of the species richness and density (R 2 : 71.9%-98.0%). The relationship between crustose lichens and macrolichens explained less of the variation (R 2 : 37.7%-70.1%). Effects of land-use intensity on the richness and density of genera, species, and crustose lichens were similar, except for a strong difference between the forested and the more open land-use units for epiphytic crustose lichens. For epiphytic macrolichens there were fewer significant effects. Detrended correspondence analysis indicated similar ordering of sites along the major gradients and similar length of these gradients for genera, species, macrolichens, and crustose lichens. Both genera and macrolichens are useful indicators of total lichen species richness and density. Macrolichens, however, are more suitable indicators than genera owing to (1) their § § § Macrolichens and Lichen Genera as IndicatorsBergamini et al.more stable taxonomy of species than of genera, (2) the potential that nonspecialists could do the sampling,the limited use of genera data for species conservation, and (4) the fact that species extinctions will not be indicated by nonmonotypic genera. Resumen: En la búsqueda de métodos rentables para la medición y el monitoreo de la diversidad de líquenes, probamos el funcionamiento de dos posibles indicadores: diversidad de géneros de líquenes y diversidad de macrolíquenes. Estudiamos la vegetación de líquenes en ocho países europeos situados en seis regiones biogeográficas diferentes. En cada país, muestreamos los líquenes terrestres, saxícolos y epifitos en 16 parcelas ubicadas en seis unidades de uso de suelo (1 km 2 cada una) que representaban un gradiente de uso de suelo desde bosque maduro hasta tierras agrícolas (n = 48). Encontramos 768 especies diferentes de líquenes pertenecientes a 157 géneros. Las relaciones entre riqueza y densidad de géneros y especies, especies y macrolíquenes y líquenes costrosos y macrolíquenes fueron altamente significativos (p <0.001) para todos los sustratos combinados y para líquenes epifitos y saxícolos. La riqueza y densidad de géneros y macrolíquenes explicaron una buena proporción de la variación de...

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