debris flows; dendrogeomorphology; growth disturbances; age effects; Crimean Mountains

The Crimean Mountains (Ukraine) are renowned for the highest occurrence of debris flows along the northern coast of the Black Sea, but information on their origin, frequency and triggers is widely lacking. This study reconstructs a regional time series of debris flows in eight catchments located on the slopes above Yalta. Dendrogeomorphic analyses were performed on 1122 increment cores selected from 566 black pines (Pinus nigra ssp. pallasiana) with clear signs of external damage induced by past debris-flow activity. The trees sampled were divided into old and young trees. The sample contains 361 young trees with post- 1930 innermost rings and 205 old trees with pre-1930 germination dates. The two groups of trees were analyzed separately to identify possible age effects in the reconstructed debris-flow series and to assess the ability of P. nigra to record geomorphic disturbances over time.