During the past 30 years an increase in forest damage has been observed in the forest of Baden-Württemberg, a federal state in the Southwest region of Germany. Forest damage has been frequently related to acid rain resulting in accerlerated soil acidification and induced nutritional deficiency. In some of the areas of Baden-Württemberg the soils are already acidic, e.g. in the Black Forest where the geology is mainly siliceous bedrock such granite and gneiss and does not have a high buffer capacity against the acids. However, it is difficult to make a direct linkage between acidic deposition and forest health because trees are exposed to many diverse stresses. Causes of forest decline can be grouped into two categories. One category posits direct damage to forest canopy that is reversible. The other category posits indirect damage to soil quality changes that may be irreversible and slow to recover. A model for the forest status is proposed which try to take into account of these two different sources of damage. We use the methodology of generalised additive mixed models, also called geoadditive models, to accomplish this task. The available data are from the survey of emission impact and forest nutrition (IWE) carried out by the Forest Research Centre Baden-Württemberg (FVA) in 1994 and the Chemical soil condition survey (BZE) carried out in 1992, which have a different spatial resolution. Variables collected in these survey includes nutrients in the needles and in the soils (Mg, Ca K, Mn ,P and N); Tree characteristics such as the percentage of needle losses, the age and the type of tree (fir/spruce); Soil characteristics such as altitude, geological area, direction/ type of slope, gradient of slope, relief, type of situation, soil texture, soil type, soil depth, soil water budget, nutrient balance and humus form.
Modelling the deterioration of the Baden-Württemberg forest as a function of soil and tree characteristics
MUSIO, MONICA;
2004-01-01
Abstract
During the past 30 years an increase in forest damage has been observed in the forest of Baden-Württemberg, a federal state in the Southwest region of Germany. Forest damage has been frequently related to acid rain resulting in accerlerated soil acidification and induced nutritional deficiency. In some of the areas of Baden-Württemberg the soils are already acidic, e.g. in the Black Forest where the geology is mainly siliceous bedrock such granite and gneiss and does not have a high buffer capacity against the acids. However, it is difficult to make a direct linkage between acidic deposition and forest health because trees are exposed to many diverse stresses. Causes of forest decline can be grouped into two categories. One category posits direct damage to forest canopy that is reversible. The other category posits indirect damage to soil quality changes that may be irreversible and slow to recover. A model for the forest status is proposed which try to take into account of these two different sources of damage. We use the methodology of generalised additive mixed models, also called geoadditive models, to accomplish this task. The available data are from the survey of emission impact and forest nutrition (IWE) carried out by the Forest Research Centre Baden-Württemberg (FVA) in 1994 and the Chemical soil condition survey (BZE) carried out in 1992, which have a different spatial resolution. Variables collected in these survey includes nutrients in the needles and in the soils (Mg, Ca K, Mn ,P and N); Tree characteristics such as the percentage of needle losses, the age and the type of tree (fir/spruce); Soil characteristics such as altitude, geological area, direction/ type of slope, gradient of slope, relief, type of situation, soil texture, soil type, soil depth, soil water budget, nutrient balance and humus form.
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