Physiological responses of lichens to factorial fumigations with nitric acid and ozone

This paper addresses the effects of gaseous nitric acid (HNO3) and ozone (O-3), two important air pollutants, on six lichen species with different morphological, ecological, and biological characteristics. The treatment chambers were set up in a factorial design consisting of control chambers, chambers fumigated with HNO3, with O-3, and with HNO3 and O-3, together. Each species showed a different sensitivity to the fumigations, reflecting the physiological variation among species. Our results clearly indicate that HNO3 is a strong phytotoxin to many lichens, and that O-3 alone has little effect on the measured parameters. The combined fumigation effects of HNO3 and O-3 were not significantly different from HNO3 alone. Published by Elsevier Ltd.