Detailed reconstruction of gully headcut retreat using exposed tree roots: a case study from the Vsetínské vrchy Mts. (Outer Western Carpathians)

Gully erosion is a widespread natural hazard that causes substantial financial losses every year. Dendrogeomorphic (tree ring-based) methods are a good alternative approach for assessing gully development in forested areas. The majority of previous dendrogeomorphic studies dealing with erosion focused on sheet erosion or erosion rates in the active channels of old, stabilized gullies. This study aims to asses newly originated gully development based on an analysis of exposed tree roots. Moreover, the root exposure data were used to calculate rates of linear and areal gully headcut retreat (GHR). In total, 81 samples (microcuts) from common spruce (Picea abies(L.) Karst) were analyzed for anatomical responses to root exposure. The existence of the shallow channel preceding the gully itself was identified. This GHR reconstruction (for a limited time period of eight years) provides evidence of highly active gully development in the forested area of the Flysch Carpathians that is comparable with results from semi-arid regions.