Lichen physiology and air pollution. I. Physiological responses of in situ Parmelia sulcata among air pollution zones within Biel, Switzerland

Parmelia sulcata, a rather pollution resistant lichen species, was collected at 13 locations with different levels of air pollution from its natural habitat in the city and the suburbs of Biel, Switzerland, The growth rate, net and gross photosynthesis, release of C-assimilates, dark respiration, and protein and chlorophyll content were determined. Growth rates differed maximally by a factor of 7 with the lowest rates at fee central and most polluted locations of the city. The chlorophyll content was highest in the center and maximally four times lower at the suburban locations. The protein content, dark respiration, and net and gross photosynthesis did not differ significantly between the 13 locations when based on the dry weight, but the percentage of C-assimilates released by the algal cells was up to 15 times lower in the center. These results are different from previous reports where the transplant technique had been used, indicating that the long term effects of air pollution on the lichen metabolism under natural conditions are not the same. Key words: photosynthesis, C assimilation, growth, chlorophyll, dark respiration.