Dating of geomorphological processes using dendrogeomorphological methods

The object of this study was to develop methods for investigating recent geomorphodynamics of aggradation processes by dendrogeomorphological analyses of the stems and the roots of partially buried spruces. Every accumulation process causes growth reactions in the affected trees, which is reflected in the growth rings. Analysis of the growth rings enables us to determine the time and the magnitude of burial. Yet the ‘critical burial depthʹ’ which when exceeded causes the death of the tree, is 1.6 to 1.9 m. The burial of a spruce stem causes the sprouting of adventitious root horizons. A single event may cause simultaneous sprouting of up to six root horizons, of which the uppermost horizon usually is the strongest one. The dating of the onset of sprouting of the oldest adventitious roots among each root system enables one to establish absolute dates of debris flow events with an accuracy ±0 to +3 years. Yet this method is very time-consuming. The simplest dating method proved to be the determination of burial events by the onset of a pronounced reduction of increment in the stem-wood of the affected trees, with only one core to be taken of each tree. This method therefore allows a spatiotemporal reconstruction of aggradation processes. The information recorded on the stem, cross-section of stem by the growth ring pattern, lessens with :increasing burial depth though.