The Influence of Air Pollution on Corticolous Lichens near the Strathcona Industrial Area, Alberta

Résumé

Lichens that grow on the bark of mature trees were studied at 35 sites along an air pollution gradient east of Edmonton, Alberta. Data on species composition, richness, and cover were recorded in October 1999 in a matrix of sites that extends from a known source of pollutants (the Strathcona Industrial Area) east across Strathcona County. Air pollution is affecting the corticolous lichen community. Lichen species richness and total cover increased with distance from the pollution source. Species richness in areas distant from pollution was roughly twice that in areas near the Strathcona Industrial Area. Xanthoria fallax and Phaeophyscia orbicularis were the most pollution tolerant lichens. Xanthoria hasseana, Ochrolechia arborea, Physcia adscendens, Parmelia sulcata, and Melanelia albertana were rare or absent near the pollution source and common in more distant areas. Most of the 15 species assessed were sensitive to air quality to some degree. Some lichens near the refineries and in Sherwood Park showed abnormal coloration and poor thallus integrity indicative of stress. We discuss implications for human health.