Dieback and decline of both natural and planted forests has recently received considerable attention. This attention has been focused on Europe and North America where anthropogenic pollution has been identified as one of a number of factors which affect forest health. Forest dieback and decline is, however, by no means restricted to Europe and North America. There are reports of trees and stands affected by this syndrome in other forested regions of the world. While symptoms may be strikingly similar between regions, this condition can be brought about by a great variety of abiotic and biotic factors, often interacting in a complex manner. Some diebacks and declines are the result of natural processes which are an integral part of the dynamics and succession of forest communities. Others appear to be the result of human activities including land use, vehicle emissions and industrial processes. Still others are related to climatic variations, site, pests or the use of planting stock from a narrow genetic base. In a number of cases, the causal factors responsible for a dieback event are not known. The purpose of this discussion draft, prepared on the basis of literature surveys, correspondence and personal experience, is to provide a review of forest dieback and decline in a global context. Areas of commonality and differences between various decline events are examined, as are the mechanisms which cause decline. The frequency of occurrence, pattern and intensity of some dieback and decline events may serve as an indicator of forest response to global change. It is therefore essential for foresters, ecologists, biologists and scientists from related disciplines to understand the mechanisms and factors involved in events of dieback or decline so that the ecological implications of their occurrence can be accurately assessed and that appropriate monitoring and management systems can be put into practice.
48 (Schäden infolge unbekannter oder komplexer Ursachen (nach Holzarten geordnet)) 425.1 (Gase und Schwebestoffe (Rauchschäden)) [100.3] (Mehrere Länder oder Teile des Erdballs, die nicht eine organische Einheit bilden)
