DENDROCHRONOLOGICAL METHODS IN THE STUDY OF GEOMORPHOLOGICAL NATURAL HAZARDS IN THE CARPATHIANS

Abstract

The specifics of dendrochronological methods in the study of the most common hazardous slope processes are examined: snow avalanches, landslides, rockfalls and debris flows. The dendrogeomorphological methods mainly refer to the study and dating of tree rings of coniferous species (Larix decidua, Picea abies, Pinus cembra, Pinus mugo) and less deciduous species (Fagus sylavatica). In this way, they aim to interpret past events recorded in the structure of the tree rings in terms of their deformations and damage. The most typical signs of response to geomorphological natural hazards are mechanical disturbances including injures, scars and raising ducts on trees, inclination of tree stems, broken brunches and crowns and denudations of roots. Dendrogeomorphological methods are valuable tools for reconstructing hazardous geomorphological processes under conditions of an insufficient stationary monitoring network for natural hazards. Moreover, such methods allow not only dating and thus determining the recurrence of natural hazards, but also spatially determining the coverage of the territory by hazardous geomorphological processes. This function is particularly important This characteristic is particularly important for the assessment of remote regions with complex topography, especially mountainous regions. A retrospective analysis of earlier developments in this field shows the suitability of such methods for the reconstruction of hazardous geomorphological processes in mountainous regions.
 The application of dendrogeomorphological methods in the reconstruction of hazardous geomorphological processes was introduced in geomorphological studies in the 1970s. Most dendrogeomorphological studies on mountain regions are currently being carried out in Switzerland, the Czech Republic, France, Spain, Italy, Poland, Romania and the USA. Dendrogeomorphological methods are among the most important absolute methods for the identification and reconstruction of landslides, especially those that have occurred in recent centuries. Landslides, like other hazardous geomorphological processes, particularly affect the growth of trees, which is reflected in their impaired growth. Dendrogeomorphological methods are also considered reliable to reconstruct, predict and mitigate the consequences of mudflows.
 Czech, Polish and Romanian Carpathians are the common objects of the dendrogeomorphological studies in the Carpathians. Here, the reconstruction of snow avalanches is one of the most common dendrogeomorphological research in the Carpathians. At the same time, while in the parts of the Carpathians located in the other countries, such studies are active, in the Ukrainian Carpathians, still with insufficient possibilities for automated monitoring, such studies are scarce. The authors have already successfully tested such methods for the reconstruction of snow avalanches in the Ukrainian Carpathians (Chornohora and Borzhava massifs) while learning from Romanian experience in the Rodna and Maramuresh massifs of Eastern Carpathians. The dendrochronological results are congruent to stationary snow avalanche observations, evidence of residents and relevant services. The perspective of the authors’ studies in the field is related to the further testing of dendrochronological methods in the reconstruction of other dangerous geomorphological processes (landslides, rockfalls, mudslides) in the Eastern Carpathians on the example of the Chornohora and Poloninsky massifs using samples of damaged tree-rings of Picea abies, Abies alba, and Fagus sylvatica.
 Key words: dendrogeomorhological methods, geomorphological natural hazards, Carpathians, snow avalanches, tree rings.