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The corticolous epiphytes were studied in the area of Wawa, Ont. where the atmosphere is polluted by sulfur dioxide, emitting from an iron-sintering plant. An inventory of the epiphytic flora for the region was made and the distribution of SO2 in the area, as well as the pH and sulfate content of water, soil and vegetation were determined. The fallout pattern of SO2 and the chemical indices (ph and SO4 --) of water and soil were correlated with the epiphytic flora of the region in order to find species which can serve as biological indicators of SO2- pollution.
Colloque
To understand the effect of light on the growth rate of lichens one should consider the thickness of the cortex, the limited quantity of the chlorophyll, subnormal moisture conditions, light absorbing pigments and the presence of fluorophors like atranorin. The fluorescence spectrum of atranorin and the absorption spectrum of chlorophyll are compared. A role of atranorin in the utilization of low light intensities and of lichen pigments in the quenching of high light intensities in the lichen thallus is suggested.
