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Germany

European Forests Thriving in High Ozone Areas

Growing fears that pollution is damaging European forests beyond repair may have been ungrounded, according to research showing that wooded areas are actually thriving.

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Are European trees protecting themselves from pollution?

A European Forests Institute study of 39 countries suggests that forests across the continent may actually be helped by continued carbon dioxide emissions and the new evidence suggests they may have already greatly benefited from the phenomenon of human-created or anthropogenic CO2.

Air pollution by other damaging gases has been significantly reduced in central Europe over the past two decades while ozone levels have been on the rise, according to research collected from European databases that include ozone measurements from about 100 stations in Austria and Germany.

The study, covering forests from Portugal to the Urals in Russia, shows what German ecologists had been fearing for two decades - that their woodlands are in danger.

However, even though the amounts of ozone reported across Germany and Austria have exceeded the United Nations critical level, known as AOT40, by approximately seven times and have been shown to reduce tree growth by 10 percent in controlled experiments, the expected ecological disaster has not materialized.

Baum des Jahres

Happy and healthy: A Euro tree.

In these areas of Germany and Austria where a seven-fold level has been reported, the forests are far from devastated. Experts studying the phenomena have reported that not only is there no sign of damage, but in fact there have been marked improvements in the health of trees and growth in the crown areas at the top of the trees has increased.

Instead of dying, trees are thriving on CO2

The research report shows that under present ozone levels, the trees in the target grid section in Germany and Austria do show some reduction of photosynthetic CO2 absorption. This is particularly evident in old trees at high altitudes where the levels of ozone are much more extreme, and in trees that are experiencing "additional climatic stress."

However, the researchers are quick to point out that the reductions in carbon dioxide being absorbed by the trees "are in no proportion to the massive excess of the AOT40."

So what does this all mean and how is it possible? With levels so high and evidence showing reduction in tree growth at a fraction of these current levels, trees across Europe should be suffering a 70 percent reduction in growth, according to research. Instead, growth conditions seem to have improved almost everywhere, except at high altitudes and under conditions of more-than-usual climatic stress.

Blätter, Baum

Leaves may hold the answer to the forests' recovery.

One possible suggestion is that the once-adequate critical level of ozone exposure is no longer suitable for research purposes. But why? Researchers suggest that the answer comes not from using the level of atmospheric ozone as the critical level but the ozone dose absorbed by the trees. This would mean a new level based on the ability of certain leaves to absorb carbon dioxide.

Increasing levels of climactic change may be protection

According to researchers, these findings suggest that the continuous changing of the Earth's atmospheric conditions must be taken into consideration when monitoring the effects of pollution on European forests. Predicted damage by ozone poisoning may have been offset by the increasing amounts of other gases and climactic factors arriving in the air surrounding the planet.

The Center for the Study of Carbon Dioxide and Global Change in the United States supports the theory that the trees have adapted in a way to reduce ozone damage. The Arizona-based research body believes that the lack of ozone damage in the forests of central Europe may well be the result of benefits arising from rising levels of CO2 content in the air.

Baum Waldsterben

A deadly future?

If it is proved that rising CO2 levels are in some way protecting the trees, experts can only wonder at the widespread damage that will occur if this changes and the forests begin to show the catastrophic effects that have been predicted for the past 20 years.

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