. Advancing knowledge of forests and rangelands : 1984 research accomplishments. Wood Research United States Bibliography; Forests and forestry Research United States Bibliography; Forest fires Research United States; Insect pests Research United States; Forest management Bibliography. Effects of Atmospheric Pollutants on Trees and Forest Ecosystems Recent research on the effects of air pollutants on forested ecosystems has highlighted the sensitivity of various tree species and ecosystems to air pollu- tion or to the secondary effects of those pollutants. The decline and mortality of red spru
. Advancing knowledge of forests and rangelands : 1984 research accomplishments. Wood Research United States Bibliography; Forests and forestry Research United States Bibliography; Forest fires Research United States; Insect pests Research United States; Forest management Bibliography. Effects of Atmospheric Pollutants on Trees and Forest Ecosystems Recent research on the effects of air pollutants on forested ecosystems has highlighted the sensitivity of various tree species and ecosystems to air pollu- tion or to the secondary effects of those pollutants. The decline and mortality of red spruce in the Northeast has received wide atten- tion because of the possible involvement of atmospheric deposition. A 1983 sur- vey revealed that the root pathogen Armillaria mellea is associated with this decline at low elevations but is virtually absent from high-elevation forests, where the decline is most severe. The lack of this root pathogen at high ele- vations may be linked to the increased air pollutants found at higher elevations, particularly lead. A cooperative study between the Northeastern Forest Experi- ment Station and Yale University showed that Armillaria is sensitive to lead. In high-altitude soils with high concentra- tions of lead and in low-altitude soils with added lead, production of the shoe- stringlike structures of Armillaria that grow through the soil from diseased to healthy trees was significantly less than in untreated soils. There may also be an interaction between lead and acidity (pH); lead is more inhibitory when pH is lower (more acid). Investigators have examined the effects of ozone air pollution on trees and forest ecosystems in the mountains of Virginia and in the mountains east of Los Angeles in California. In Virginia, ozone and its photochemical precursors are the major pollutants. Ozone concentrations are higher during the growing season (April to October). Eastern white pine was the first species to show symptoms, including growth loss,
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