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R. F. HUTTL AND W. SCHAAF Brandenburg Technical University Cottbus, Chair of Soil Protection and Recultivation, P.O. Box 10 13 44, 03013 Cottbus, Germany The health status of forest trees and stands is determined by numerous site factors such as chemical, physical, and biological soil factors, water supply, climate, weather conditions, management history as well as atmospheric deposition impacts. In this context, the nutrient supply is an important evaluation parameter. Forest trees well supplied with nutrients are more resistant to stresses that affect the forest ecosystem than other trees. This is true for both biotic and abiotic influences. Therefore the investigation of the so-called ´new type forest damage´ was aimed at the exact determination of the health status of damaged trees. When considering the complete forest ecosystem, health (=vitality) means the sustainable ability to withstand negative environmental influences and still remain stable and productive. From this viewpoint, an optimal nutritional status is a prerequisite for an optimal health status. The term ´new type forest damage´ comprises a number of damage symptoms which have been observed in various tree species on very different sites since the mid-1970s, particularly in Europe and North America. However, they occurred much more intensively in the 1980s. Generally, this forest damage was thought to be related to negative impacts of air pollutants.

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1. Introduction; R.F. Hüttl, W. Schaaf. 2. Visual Mg-Deficiency Symptoms (Coniferous, Deciduous Trees) and Threshold Values (Foliar, Soil); P. Ende, F.H. Evers. 3. Temporal and Spatial Development of Mg Deficiency in Forest Stands in Europe, North America, New Zealand; G. Landmann, et al. 4.1 Biogeochemistry of Mg in Forest Ecosystems; K.H. Feger. 4.2. Tree Physiology; S. Slovik. 4.3. Influence of Magnesium Supply on Tree Growth; K. Makkonen-Spieker, H. Spiecker. 5. Causes of Magnesium Deficiency in Forest Ecosystems; K. Katzensteiner, G. Glatzel. 6.1 Soil Chemistry; S. Augustin, et al. 6.2. Tree Nutrition; M. Kaupenjohann. 6.3. Structural Aspects of Mg-Deficiency; S. Fink. 6.4. Fine Root Development; S. Raspe. 7. Evaluation of Different Mg Fertilization Strategies; W. Schaaf. 8. Concluding Remarks; R.F. Hüttl.

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