Soil succession in relation to different kinds of vegetation on a subalpine forest fire site in the Northern Limestone Alps
Schaufler Judith, University of Natural Resources and Life Sciences, Vienna (AT)
The study investigates secondary soil succession on a steep subalpine site in the Northern Limestone Alps of Austria after substantial vegetational and soil losses induced by a stand replacing forest fire in 1950. The main objectives were (1) to estimate the extent of soil developement in relation to different kinds of vegetation, (2) to quantify macroscopically visible charcoal in these soils and (3) to test the potential of FTIR-analysis to identify the vegetational litter sources of the humus layers for subsequent identification of typical patterns of succession. The field survey included the firesite and an undisturbed reference site. Sampling design was stratified by vegetation (grasses, heather, larch, spruce, mountain pine) and included morphological soil profile descriptions and volumetric soil samples. Total belowground organic carbon and nitrogen stocks were determined including litter/soil, dead wood, charcoal and roots. According to the results the soils of recolonized sites at the firesite have recovered by around 40% as compared to typical site potentials (reference: 8,4kgC/m² and 0,30kgN/m²). Soil layer analysis reveals the largest regeneration discrepancies occuring in the soil stocks of the Oh-horizons. Total sequestration varies considerably according to vegetation with hitherto heather showing the highest regeneration potential comprising a total of 5,8kgC/m² belowground, compared to 3,5kg/m² for grasses and spruce, 2,8kg/m² for mountain pine and 1,8kg/m² for larch. The amount of charcoal in the soils of the firesite is low with an average of 60g/m², probably due to heavy erosion. The intended FTIR approach for identifying the vegetational source materials of the humus layers proved to be too complex in the course of this study, however potentials for further research were highlighted.