Effects of Sulphur Dioxide on Lichen and Moss Transplants
1973
LeBlanc, Fabius | Rao, Dhruva N.
Injury symptoms in lichen and moss transplants have been correlated with the SO_2 concentrations prevailing at their exposure sites in the Sudbury area during 1970. For this purpose bark—discs bearing lichens and mosses were cut out from an unpolluted region nearly 40 km E of Sudbury. The discs were individually photographed and the epiphytes on them were inventoried. These were then arranged in groups of six in cut—out holes on wooden boards. Two such boards were fixed at a height of 8—10 m on a tall, exposed tree at each of the 19 sites selected in the five SO_2—pollution zones delineated for the area. After one year of exposure, the boards were carefully removed and the discs were rephotographed. The changes in epiphytes, especially in Parmelia sulcata, taking place in the different pollution zones were compared with respect to external and internal morphology, biomass, acidity, total sulfur, and chlorophyll. The results indicate that different concentrations of SO_2 produce different sets of harmful effects which appear to be more or less directly related to the levels of pollution. So far the trend has been to relate the floristic and/or phytosociological characteristics of lichens and mosses to the ambient concentrations of SO_2, but in the present study a quantitative correlation has been sought between the levels of injuries produced in these organisms and the levels of SO_2 to which they are exposed in the field.
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