Dendochronological investigations on the frequency of debris flows in the Italian Alps

Abstract

With the help of the example of the Kaserbach debris flow cone in the Dolomites of Prags / Southern Alps, the analysis of debris flow frequencies by dendrochronological methods is demonstrated. Episodic burying of trees causes sprouting of secondary root systems at the top of each of those aggradations. By age determination of such layers of adventitious roots, as well as of the time of drastic decline in annual increment of the stem (suppression) due to aggradation, and by dating deaths of trees resulting from deep aggradation on the one hand, also by age determination of trees and shrubs growing upon debris flow cones on the other hand, a stratigraphic division comprising, in the study area, the last 246 years can be constructed, which permits sufficiently accurate conclusions on the frequency of episodic debris flows. The methods applied will be presented in detail, their problems and limits being discussed in conclusion.