State of Scientific discusion about the causes of the novel forest decline in the federal republic of Germany and surrounding countries : Air Pollution and Forest Decline. 14th International Meeting for Specialists in Air Pollution Effects on Forest Ecosystems

1989

Unselbständiges Werk

9091

200034636

The scientific discussion about novels forest decline lasts now nearly ten years. It was initiated by reports on fir dieback in southern Germany and very early associated with the impact of sulfur dioxide and its reaction products anticipated to lead to soil acidification processes. Today the scope of the problem is much broader discussed. Since 1980 and 1982 in southern and other parts of Germany, respectively, damage on Norway spruce has significantly increased. The most important symptom observed ist the so called mountainous needle yellowing, associated with the deficiency of magnesium. Although spruce and fir decline came to a standstill or even showed recovery to a certain extent in recent years, decline of decidous trees increased steadily since 1984. However, symptomatology as well as the role of influencing factors like climate, soil or the pollution environment are yet not elucidated. During recent years research has produced a aubstantial amount of detailed information, especially in respect to the symptom of needle yellowing. As state of the art, the following interaction of causal factors seem to be of greatest probability: The temporal development is controlled by the observed increase of atmospheric ozone and a depletion of nutrients in the soil due to progressing soil acidification. The vertical profile of ozone as well as fog events seems to account for the geogenic soil factors induce the spatial differentiation. The short term temporal development on the other hand seems to be incited by climatic factors. However, it has to be emphazised that the development of damage in all affected tree species would not have been apparent without climate as influencing factor. On the other hand, climate alone could not have caused forest decline to such an extent without appropriate unfavourable soil or pollution conditions. The elucidation of the interaction of these factors is seen as major task in future research, since despite all scientific Progress made so far, major gaps are still exsistent.