Combining terrestrial laser scanning androot exposure to estimate erosion rates

Aims: This paper aims to analyze the reliability of exposed roots oriented perpendicular to the slope to quantify sheet erosion rates based on accurate reconstruction of topography using terrestrial laser scanner (TLS). Methods: The study was performed in an experimental sandy badland located in Central Spain. Sampling procedures were conducted in three different homogenous hydrological response units (HRU). We derived eroded soil thickness from by obtaining accurate microtopographic data using TLS. In addition, dendrogeomorphic procedures, based on anatomical changes in root rings, were used to determine the first year of exposure of 46 Pinus pinaster roots. Results: Results indicate that medium-term (±30year) erosion rates obtained from roots growing perpendicular to the slope were significantly different from those obtained from exposed roots growing parallel to the slope (p-value <0.05). However, at short term (up to 5years), result agree with those obtained from erosion pin monitoring at the study site, which confirms the potential of reconstructions based on perpendicular roots. Conclusion: The utility of exposed perpendicular roots coupled with accurate eroded soil estimation has been proved. It allows theextension of the applicability of dendrogeomorphic approaches, particularly for ungauged badlands where instrumental data is scarce or completely missing.