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ACID DEPOSITION AND FOREST DECLINE
Citation:
Johnson, A. AND T. Siccama. ACID DEPOSITION AND FOREST DECLINE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-83/326.
Description:
The location, topography and other characteristics of the high-elevation forests of eastern North America cause them to be receptors of high levels of acid deposition and airborn trace metals. No other major forested areas in the U.S. are subjected to such intensely acid cloud moisture, such heavy acid deposition, and such high rates of trace-metal deposition. The vulnerability of these forests to the pollutants has not been documented, but because of the spruce decline it is indeed reasonable to suspect vulnerability. Current data shows several possible pathways by which acid deposition could contribute to spruce mortality, but at this time none of these pathways are supported by convincing evidence. The framework for Al toxicity proposed by Ulrich is not consistent with the data generated. The evidence regarding a triggering effect of drought is substantiated by data, but it is not know whether drought is sufficient to cause the dieback and decline or whether an additional stress from pollution is involved. In viewing the spruce dieback and decline as a stress-related syndrome, it is suggested the possibility of multiple stresses is possible. (Copyright (c) 1983 American Chemical Society.)