Influence of effluents from a zinc factory on lichens

• Published in: Ecological monographs 1975-01, Vol.45 (2), p.183-198
• Main Author: Nash, Thomas H.
• Format: Article
• Language: English
• Subjects: Cadmium; Forest habitats; Heavy metals; Lichens; Smelters; Species; Sulfation; Sulfur dioxide; Water pollution; Zinc
• ISSN: 0012-9615; 1557-7015
• DOI: 10.2307/1942406

Lichen species richness and abundance are reduced by approximately 90% in lichen communities near a zinc smelter at Lehigh Water Gap in comparison with the lichen communities of Delaware Water Gap. The principal cause of the impoverished lichen flora in the Lehigh Water Gap area is probably high concentrations of zinc. Of the non-pollution and pollution factors considered, only abnormal soil concentrations of zinc and cadmium extend beyond the limits of the lichen impoverishment zone. Because Zn is present in concentrations generally 100 times higher than that of Cd and because Cd is experimentally shown to be no more toxic to lichens than is Zn, it is probable that Zn is the more important, detrimental factor to lichens in the Palmerton area. Near the smelters, Zn, Cd and sulfur dioxide are all present in sufficiently high concentrations to be detrimental to lichen growth and survival. However, at the perimeter of the lichen-impoverished zone, only Zn is present in high enough concentrations to be phytotoxic. Although microclimatic alteration in forested areas near Palmerton may be sufficiently great to be a stress for a few lichen species that are adapted to shaded conditions, no microclimatic differences were demonstrable between Delaware and Lehigh Water Gaps for open habitats where most lichen species normally occur in this area. Variations in such factors as lichen geographical range, climate, substrate composition and abundance, and fire history are probably of negligible importance in explaining the reduction in lichen numbers or abundance in Lehigh Water Gap.