Columbia subject headings:
Forest ecology.
Plants--Effect of acid precipitation on.
Plants--Effect of air pollution on.
Trees--Wounds and injuries.
Harvard subject headings:
Acid rain.
Air--Pollution
Forest declines.
Forest ecology
Forests and forestry.
Plants--Effect of acid precipitation on
Plants--Effect of air pollution on
Trees--Effect of acid precipitation on.
Trees--Effect of air pollution on.
Trees--Wounds and injuries.
Princeton subject headings:
Forest ecology.
Plants--Effect of acid precipitation on.
Plants--Effect of air pollution on.
Trees--Wounds and injuries.