Alpine wildfires and their impact on landscape development

In the last centuries, numerous wildfires devastated considerable parts of the subalpine krummholz and forest areas near Innsbruck. On grounds of the downwash of the exposed soil, many of the affected slopes are still bare of vegetation. Intensified slope processes, a changed water balance and an increased probability of avalanches lead to an enhanced risk of natural hazards in the vicinity of the slopes. Archive investigations make clear that deforestation by wildfires is of more than regional importance in the Northern Alps. However, investigations on the alpine fire ecology in this region are comparatively sparse. The destruction of the plant cover and the downwash of the soil produced habitats which are extremely hard to recover. Furthermore, the uncovering of the pre-weathered rock surface provided a source of easily erodable loose sediments. A rough estimate of the sedimentation rates points to a 10 to 100-fold enhanced overall removal. The intensified mobilization of loose debris leads to an enhanced danger for roads and houses at the foot of the slopes during extreme precipitation events. The aim of the applied project is to provide a comprehensive reconstruction of the location, the temporal distribution and the recurrence interval of the wildfires in the limestone Alps north of Innsbruck (Karwendel, Wetterstein, Lechtaler Alps). The fire areas of different age provide an ideal experimental setting to work out the ecosystem`s regeneration under varying topographical and geological conditions. The succession of the vegetation cover will be fixed by mapping of soils and vegetation. The changes of the water and sediment budget are to be quantified by geomorphological mapping, runoff and denudation measurements. The loose sediments bodies accumulated under the disturbed slopes will be investigated by digging, to establish the existence, depth and age of black carbonic layers. Regarding the majority of the burnt slopes, there is a close interaction to the land-use and cultivation history. The investigations are expected to make clear the role of the wildfire events as a part of the natural and cultural process system of the region, the impacts on the cultivated land, and the potential for a sustainable development.