The on field differentiation of snow avalanche- and debris flow-induced scars in trees as a fundament for improving dendrogeomorphic sampling strategy (case study from the Great Cold Valley in High Tatra Mountains)

Abstract

Snow avalanches (SA) and debris flows (DF) are among the widespread geomorphic processes in high mountains. One of the most reliable method for determining their historical occurrence is related to dendrogeomorphical analyses. Sampling focused only on one process suffers from the noise caused by disturbances induced by the other process. Thus, the aim of this paper is to find specific parameters of stem scars that significantly differ when they are caused by different processes. For this purpose, six parameters of 102 sampled scars on mountain pine (Pinus mugo var. mugo) individuals growing on the polygenic debris fan in the High Tatra Mountains were recorded. For the verification of origin of scars from historically known DF and SA events, the intra-seasonal dating of callus tissue using microcuts was performed. 50 DF scars and 52 SA scars were identified and analysed. Several significant differences were identified, which serve as recommendations for a future sampling strategy. DF scars were significantly longer, wider, and occurred at lower distances above the ground in comparison with SA scars. DF scars expressed a significant negative relationship between scar length and its distance above the ground. The selection of scars with described parameters for a pointed analysis of SA or DF could help with sampling of scars caused by the analysed process.