!!!Waldsterben

Forest Dieback: This term comprises a large variety of damages that 
weaken and kill off individual trees and in extreme cases can threaten 
large areas of forests. The causes of forest dieback are not fully 
understood. Recent damage to forests has also occurred in areas where 
the air is not polluted and has been traced back to the transportation 
of pollutants through the air over long distances. Damage can be 
caused by heavy metals getting into the ground via acid precipitation; 
sulfur dioxide, ozone, chlorine and nitrogen compounds and 
hydrocarbons are assimilated by the plants directly. Climatic changes 
may aggravate these effects, resulting in needle or leaf loss, 
decreasing crown density and lower increment levels. Gradual die-back 
can also be caused by secondary pest infestation or weakened 
resistance against extreme weather conditions. In order to record the 
conditions and changes of the most important tree species, an 
Austrian-wide network has been set up with thousands of control trees 
that are observed throughout the year. In 1993 46 % displayed 
needle or leaf loss; the condition of pine trees (63 %), beeches 
(55 %) and oak trees (62 %) was very bad, while spruce and 
fir trees showed a tendency of improvement in comparison with the 
years before. The development in the condition of forests and woods is 
published annually in the forest report by the Ministry of 
Agriculture.


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