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.