Modellierung der Vegetationshöhenstufen und der Areale von Buche und Tanne für die Schweiz

Modelling of the vegetation belts and the areas of beech and silver fir for Switzerland The vegetation belts and the distribution area of beech and silver fir in Switzerland are an essential basis for the classification of forest site types with ecograms and therefore for site-specific recommendations of tree species and for forestry. Their limits, which are to a large extend defined by climatic factors, were until now only defined on a qualitative basis. For the future usage of the ecograms for tree species recommendations the limits must be described quantitatively, so that they can be modelled for the future with climate scenarios. With maps in a high spatial resolution of the forest-relevant climate variables and with additional important site parameters, those parameters were selected, which were relevant for the actual limits of the vegetation belts as well as for the beech and silver fir areal. The altitudinal belts were modelled by means of a linear regression between the known position of a representative altitudinal limit and the respective climatic factors at that position. The areal limits were modelled with a fuzzy logic approach. The climatic variables for the time span 2070–2099 were calculated on the basis of the climate (emission) scenario A1B (regional models RegCM3 and CLM), so that the limits of the altitudinal belts and the areas could be modelled for the future. The results of the model approaches are ecologically plausible. This could be shown in a comparison with the forest site types on the sample points of the National Forest Inventory and in an expert evaluation. The developed vegetation and climate maps as well as the modelled projections of the altitudinal belts in the future are the basis for the inclusion of climate change in the recommendation of tree species. They serve as decision support for forest managers and authorities in the forestry planning which is confronted with many uncertainties.