Air Pollution: Synthesis of the Role of Major Air Pollutants in Determining Forest Health and Productivity

Abstract

Forested ecosystems are exposed to not only a physical climate, but also a modern chemical climate which has the potential to alter forest health and productivity. Recently, unexplained forest deterioration has been identified throughout extensive areas in central Europe, at high elevation coniferous sites, and apparently in commercial forestlands in the eastern United States. Deposition of pollutants from the atmosphere is suspect in playing a role in these forest deterioration phenomena. To date, no cause and effect relationship has been conclusively demonstrated between regional versus local atmospheric deposition and forest deterioration. The major hypotheses currently thought to deserve the focus of scientific investigation deal with forest alterations due to (1) gaseous pollutants (primarily O3), (2) a fertilization effect (primarily from N), (3) acpd deposition effects on foliage and soils, (4) trace metals (e.g. Pb, Cu, Cd, Ni, Zn), (5) general stress from air pollutants, and (6) deposition of organic growth altering substances. Not enough is yet known to suggest adjustments in forest management decisions which might reduce the possible effects of atmospheric deposition. However, foresters must keep informed about the current state-of-knowledge on the air pollution and forest effects issue as we all will play a role in management and policy decisions which shape the character of the environment in which future forests will grow.