Ruchy osuwiskowe w świetle badań dendrogeomorfologicznych na podstawie analizy osuwiska Sawickiego w Beskidzie Niskim = Landsilde movements based on dendrogeomorphological research based on a analysis of the Sawicki Landslide in the Beskid Niski mts

Abstract

Research concerns the problem of landslide movement, which is one of the most important geomorphological processes in the Carpathians. The aim of the studies is to determine the temporal and spatial complexity of landslide activity and to demonstrate the suitability of using different species of conifers in the dendrogeomorphological method. The Sawicki landslide located in Beskid Niski Mts., which is one of the largest landslides in the Polish Flysch Carpathians, was selected for dendrogeomorphological analysis. The dendrogeomorphological method and geomorphological mapping were used in the research. 1078 samples from conifers (fir, spruce, larch and pine) growing on the Sawicki landslide and its immediate surroundings were taken using an increment borer in 2013- 2018. The cores were taken from the upslope and downslope side of the tree stump. The width of annual tree rings were measured for each extracted core sample. The landslide activity was assessed on the basis of the eccentricity, the eccentricity index and its yearly variation. Geological and topographic maps, published data on landslides activity in the research area, precipitation data from the Research Station in Szymbark (Institute of Geography and Spatial Organization Polish Academy of Science) for 1968-2017 and from the meteorological station in Krynica (Institute of Meteorology and Water Management) for 1881-2010 were also used for dendrogeomorphological research of Sawicki landslide. The research shows that the Sawicki landslide is characterized by varied temporal and spatial complexity of landslide activity. The dynamics of displacements within the research sites and research sub-sites, including various fragments of landslides, and movements of colluvial packages is spatially mosaic and chaotic in time. Mass movements covering almost the entire surface of the landslide occurred in the years 1913-1914 and 1974-1975, while in the years 1888, 1906-1907, 1916, 1918, 1929, 1965, 1973, 1980, 1983-1985, 1997 landslide activity was recorded only in its particular parts. The largest variation in the dynamics of landslide movements is characteristic for the period 1970-1985. It was also found that in the initial stage of formation of the landslide tongue, the colluviums movement is disordered. During further downhill movement, the direction of displacement is arranged. Periods of Sawicki landslide activity refers to extremely humid years (62%) and wet years (48%) and they are consistent with the years of landslides activity in Szymbark, listed in the current literature of the subject. The most predisposed conifer species to dendrogeomorphological analysis were spruce, larch and fir. Despite its limitations, the dendrogeomorphological method is a useful tool in landslide activity research.