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Lichen transplants of Hypogymnia physodes were used in a high-density network of sites for collecting airborne metals from the atmosphere in Armadale, a small industrial town in central Scotland. The mapping of the concentrations of various metals revealed a gradient of metal values which decreased outwards from the town's steel foundry. The findings were discussed in the context of a previous epidemiological investigation of lung disease in the town.

The epiphytic lichen Hypogymnia physodes was analysed for its content of cadmium, iron and zinc in a suburb of Helsinki. The metal contents were slightly higher than those from unpolluted areas in central Finland. Elevated concentrations were found in the vicinity of a big shipyard.

Passive Biomonitoring with the folious lichen Hypogymnia physodes (L.) Nyl. has been tested in Switzerland. Multielement analyses enable qualitative and quantitative conclusions about the composition and amount of important active pollutants. Many elements correlate well with the general air pollution indicator IAP18. Hypogymnia physodes possess good accumulation capacity for important air pollutants. The method has been calibrated for Pb and Cu with technical deposition measurements. The “Passive Biomonitoring” and “Calibrated Lichen Indication Method” compose together an “Integral Biological Testing System for Air Pollution in Switzerland”. This system enables detailed statements on total air pollution in general and on single pollutants as well.

The background concentrations of lead and cadmium in the epiphytic lichen Hypogymnia physodes were determined and found to depend on altitude. The lead content increases linearly with increasing altitude, whereas the cadmium content increases up to altitudes of 900–1100 m, and then decreases above this height.

It is concluded from the high correlation between visible transplant damage and SO2 levels, that SO2 pollution gradients can be sufficiently described by means of the lichen transplantation method. The transplanted lichen species should be chosenon the basis of its SO2 sensitivity, this being neither too high nor too low in relation to the average SO2 level of the area under investigation. A description of the existing lichen vegetation or a knowledge of the SO2 variation in the area should thus precede any transplantation experiments.Hy-pogymnia physodes, which was also used successfully in transplantation experiments in Oslo (KROG & BRANDTH, 1975), showed sufficient variation in degree of damage after 6 months of transplantation in the Copenhagen area to be a useful indicator of SO2 air pollution levels. Thus, our data suggest that Hypogymnia physodes is a suitable organism for use in future transplantation experiments on air pollution levels in metropolitan areas in southern Scandinavia.

The thallus structure of a common epiphytic lichen Hypogymnia physodes growingon the bark of Pinus sylvestris under a variety of microclimatic conditions was studied by means of fluorescence and scanning electron microscopy. The disparity between the thallus layer thicknesses of specimens growing in different habitats proved to be small though obvious, and differences also appeared in the amount of gelatinous substances in the hyphal cell walls ofthe cortex and algal layer. Furthermore, the occurrence of a pored epicortex of H. physodes at dry sites is reported. The size distribution of the thalli, thallus area and the production of soralia showed a complex interaction with microclimate. Against a background of the microclimatic data collected here, humidity is considered to be the most important factor affecting the anatomy and morphology of the thallus.

The inner limits of the distribution of three common corticolous lichens are mapped in the west central Scotland area. By employing a modified version of Hawksworth & Rose's (1970) qualitative zone scale for estimating mean winter S02 using lichens, the pattern of S02 air pollution over the survey region is traced. That the lichen data reflect S02 levels rather than other factors is supported by (a) field transplant experiments which show that Hypogymnia physodes and Usnea subfloridana accumulate sulphur and exhibit morphological damage in proportion to the mean S02 levels, and to a lesser extent by (b) bark pH studies which demonstrate that a good linear relationship pertains between mean pH and S02. A new technique for determining microgram amounts of sulphur in lichen material is briefly outlined.

Continuous water saturation in Hypogymnia physodes (L.) W. Wats. leads to an increase in the concentration of atranorin. This is taken as an indication that lichen substances are metabolic by-products. Different illumination and SO/sub 2/-fumigation had no significant influence on the content of atranorin. 12 references, 1 figure, 2 tables.