Possibilities and limits of dendrogeomorphic data as a basis for defining thresholds for landslide triggering

Dendrogeomorphic (tree-ring based) methods are an effective tool for determining the spatial and temporal activity of landslide movements. Moreover, the obtained chronological data can be used for the analysis of their potential triggers. However, the use of tree-ring based chronologies for defining trigger thresholds is very rare and has not yet been critically evaluated. Given the well-known limitations of dendrogeomorphic methods, this study aims to define the limitations and advantages of this approach for trigger threshold analysis. Thus, tree-ring based data on the activity of 26 landslides, originating from 2644 tree-ring series of disturbed trees (and 180 tree- ring series of reference trees), were used in this study. Total Water Content (TWC) as a combination of pre- cipitation sum (PS) and snow water equivalent (SWE) was analyzed as landslide trigger. The obtained values of the range of trigger thresholds were relatively high. The considerable heterogeneity of the results seems to be largely influenced by the character of the data obtained by dendrogeomorphic methods. In the discussion section, all potential influences of the tree-ring based approach on the obtained results and the possibilities of their elimination are discussed. Among the most important ones can be considered the inertia of tree response to landslide movements, the ability of trees in general to capture landslide movements, as well as the use of the approach to define a landslide event. However, in addition to dendrogeomorphic influences, the heterogeneity of the landslides studied and their geological structure themselves must be taken into account.
https://www.sciencedirect.com/science/article/pii/S1125786523000516