A tree - ring reconstruction of geomorphologic disturbances in cliff forests in the Tatra Mts.

Geomorphological events are very important disturbance factors for cliff forests and forests located on steep mountain slopes. In this study we present dendrochronological reconstruction of two types of disturbances which affect subalpine forest growing in such extreme habitats in Roztoka Valley in the Tatra Mountains: landslide and rockfalls. We determine the years of death of trees found in landslide area on Czuba Roztocka which indicate the year of 1997 as the time of this event, probably related to heavy midsummer rainfall in this year. Scars on trees growing at the base of Orle Ściany cliff allowed determining the rockfall events. We found that scars, even in neighbour trees were formed in different years between 1940 and 2004. It means that they were formed rather by separate stones which fell from the cliff sporadically then a large scale fall of debris at the same time. This may suggest that rockfalls in cliffs of Orle Ściany were limited to single rocks which fell successively when erosion process separated them from the bedrock. Dendrochronology seems to be an effective method which enables long term reconstruction of gemorphological processes in the High Tatras.