Air pollution and forest decline in Central Europe

Area of Science:

• Environmental Science
• Forestry
• Ecology

Background:

• The term 'Waldsterben' (forest deaths) emerged in the 1980s, attributing Central European forest decline to air pollution.
• Initial concerns suggested widespread forest mortality due to atmospheric pollutants.

Purpose of the Study:

• To investigate the validity of 'Waldsterben' and 'neuartige Waldschäden' (novel forest damages) claims in Central Europe.
• To assess the actual impact of air pollution versus other factors on forest health and growth.

Main Methods:

• Analysis of subsequent surveys and investigations on forest condition in Central Europe.
• Examination of foliar injury, tree mortality, and growth rate data.
• Comparison of current forest health data with historical records and pollution levels.

Main Results:

• Surveys failed to confirm widespread forest death or decline in Central Europe.
• Foliar damage and mortality were localized, often linked to sulfur dioxide and other stresses.
• Climate, rather than air pollution, significantly influences tree crown condition and growth.
• Current tree growth rates in Central Europe are at historically high levels.
• Observed declines in specific species or areas are not new phenomena.

Conclusions:

• The terms 'Waldsterben' and 'neuartige Waldschäden' are inappropriate for the 1980s Central European phenomenon.
• Forest health is primarily influenced by climate, with localized pollution impacts.
• Forest decline should only be used when a general deterioration across all tree species is evident.