Using anatomical tree growth responses to date landslide movements

The dating of landslide movements is a unique opportunity to learn about their past in the absence of archival data. Dendrogeomorphic methods, based on the study of tree rings, offer an exceptional combination of accuracy and temporal range of dating. However, most landslide studies to date have been based on the analysis of macroscopic growth disturbances in trees. In doing so, the use of anatomical growth responses may be more advantageous in some aspects. Thus, this study aims to introduce the spectrum of anatomical growth responses in trees induced by landslide movements for their dating, substantiating their advantages and limitations, and comparing them with each other. Samples from roots and trunks of sycamore maple (Acer pseudoplatanus L.) growing on a landslide of known time of occurrence (May 2010) were used. Geophysical ERT measurements were performed to test the assumption of subsurface influence of landslide movements on tree growth. Based on the results focused on the intensity of changes in vessel lumen area (VLA) and percentage changes of VLA within the tree ring, anatomical changes identified in four different geomorphic situations on the landslide with expected different effects of landslide movements on tree growth were compared with each other. Responses in tree roots were generally significantly stronger compared to those in tree trunks. However, the short time series and difficult cross-dating of roots can be considered as a disadvantage. On the other hand, the identification of anatomical responses in trees with straight trunks (until now practically not used in landslide research) allows a significant expansion of the number of trees usable for landslide dating in the future.