Soil geomorphology and frozen ground conditions at a subalpine talus slope having permafrost in the eastern Swiss Alps

• We provide a spatial overlay of permafrost distribution with soils and humus forms.
• Humus form Fibric Moor can be regarded as indicative for cold conditions.
• Ground thermal regime is highly variable and characterised by insulating effects.
• The detected thermal regime is favourable for the preservation of permafrost.

At a subalpine site with permafrost below the timberline in the eastern Swiss Alps the complex interrelationship between different environmental factors was investigated by applying an integrated approach that combines soil mapping, 3D near-surface geophysics and surface and subsurface temperature monitoring. The objectives of this approach were to explore the 3D extension of isolated permafrost bodies and to relate this to surface parameters such as soils and humus forms and other extrinsic factors. Using this procedure, interdependencies between surface (soil properties and humus forms) and subsurface factors (ground thermal regime and frozen ground conditions) could be independently analysed. Although time-consuming, 3D ERI (electrical resistivity imaging) demonstrated its ability for precise permafrost mapping. Despite climate warming, super-cooling in winter along the investigated scree slopes is still efficient enough for establishing permafrost conditions. By comparing the spatial dimensions of the permafrost bodies with surface conditions, we found that thick moss or organic litter layers had an insulating effect and prevented the permafrost from melting. However, the comparison of soil units and soil thickness with the permafrost distribution did not always show an obvious relationship. This indicates that there is a complex evolution and behaviour of soils and permafrost at such sites.