COMPARATIVE-STUDIES ON XANTHORIA-PARIETINA, A POLLUTION-RESISTANT LICHEN, AND RAMALINA-DURIAEI, A SENSITIVE SPECIES .1. EFFECTS OF AIR-POLLUTION ON PHYSIOLOGICAL PROCESSES

Xanthoria parietina thalli were collected from a 'clean-air' location and from a polluted area. Ramalina duriaei thalli were collected from the same 'clean-air' location and some thalli were transplanted to air -polluted locations, where R. duriaei no longer occurs. The effects of air contaminants on these two lichens were compared under controlled laboratory conditions and in field experiments. Air contaminants and e xposure to bisulphite ions had little or no damaging effect on X. pari etina, whereas severe damage was caused to R. duriaei, as judged by ch lorophyll degradation, autofluorescence of photobionts, photosynthetic activity, membrane integrity and ATP content. The different responses presented confirm the sensitivity of R. duriaei and resistance of X. parietina to air pollution. (C) 1996 The British Lichen Society