Reconstruction of Erosion Rates in Swiss Mountain Torrents

Mountain torrents are characterised by an intensive interaction between erosion and accumulation. Continuous as well as discontinuous erosion of riverbanks covered by trees frequently cause a destabilisation and finally a turnover of the affected trees. The project started in 2003 and aims to analyse the erosion dynamics in 2 selected torrents of the Swiss Alpine area. This is done by investigating structural variations in the annual rings of exposed roots. Roots of coniferous trees show anatomical changes in the structure of earlywood cells due to exposure. This anatomical feature in the xylem of exposed roots enables us to determine the time of exposure at a resolution of one year. Consequently, a temporal and spatial quantification of erosion rates is possible. Furthermore, this methodology can now be applied to deciduous trees to determine their specific reaction to root exposure.

Combining these findings to growth variations in the stem (e.g., occurrence of reaction wood) enables us to estimate the current stability of the trees.

Contractor : Swiss Federal Office for the Environment, Forest and Landscape (formerly FOEFL; now FOEN)


Collaboration : Swiss Federal Institute on Forest, Snow and Landscape Research (WSL), Reserach group « Erd- und Felsbewegungen ».

Contact : Oliver Hitz

Publications :

Hitz, O.M., Gärtner, H., Heinrich, I., Monbaron, M. (2008): Application of ash (Fraxinus excelsior L.) roots to determine erosion rates in mountain torrents. Catena 72: 248-258. [PDF]

Hitz, O.M., Gärtner, H., Heinrich, I., Monbaron, M. (2008): Wood anatomical changes in roots of European ash (Fraxinus excelsior L.) after exposure. Dendrochronologia. 25: 145152. [PDF]

Hitz, O.M., Gärtner, H., Heinrich, I., Monbaron, M. (2008): Erosionsrekonstruktion aufgrund holzanatomischer Veränderungen in Eschenwurzeln. Schweizerische Zeitschrift für Forstwesen. in press. [PDF]

Hitz, O.M. (2007). Using exposed tree roots as a dating tool for erosion in mountain torrents. Geophysical Research Abstract 9, 07235. [PDF]

Hitz, O., Gärtner, H., Heinrich, I., Monbaron M. (2006): Reconstruction of Erosion Rates in Swiss Mountain Torrents . TRACE Tree Rings in Archaeology, Climatology and Ecology 4, 196-202

Gärtner, H., Hitz, O., Monbaron M. (2003): Jahrringanalytische Rekonstruktion von Ufererosion und Schwemmholzaufkommen in Schweizer Wildbächen. FAN-Agenda 02/2003, 1617.