The dendrogeomorphic use of shrubs for the detection of landslide movements: A case study of Corylus avellana L.

Abstract

Dendrogeomorphic-based landslide activity dating is a commonly employed scientific approach used to detect historical landslide events with subannual precision. Trees are dominantly used for this research, but in some localities, current dendrogeomorphic methods are not suitable due to their exclusive occupation by shrub species. Nevertheless, shrub species have recently been successfully used in dendroclimatic research. Thus, this study aims to evaluate the applicability of common shrub species in Europe (Corylus avellana L.) in dendrogeomorphic research on landslides. In total, 71 stem samples from 11 shrub groups were macroscopically and microscopically analysed. Nearly half of the samples provided evidence supporting the presence of tension wood as a response to stem tilting due to landslide movement. The intensity of tension wood expressed by changes in vessel lumen area corresponded to the intensity of stem tilting, but no relationship was found for ring eccentricity. Moreover, the eccentricity of rings was found to be inapplicable to landslide event detection due to the short length of the studied C. avellana ring series. Nevertheless, the analysis of tension wood provided evidence of two past landslide events (2010 and 2014) and the absence of chronological noise. Moreover, the onset of tension wood was very abrupt, enabling the dating of landslide movements with seasonal precision. This assumption was verified by an analysis of potential triggers: extreme precipitation and high river discharge. Moreover, the roots of C. avellana exposed during the triggering flood undercutting the landslide base expressed a similar anatomical response to exposure, as seen in the cases of broad-leaved tree species. The results of this study could distinctly extend the use of dendrogeomorphic analysis of landslides into regions with no tree vegetation.