Université de Fribourg

Wood anatomical changes in roots of European ash (Fraxinus excelsior L.) after exposure

Hitz, Oliver M. ; Gärtner, Holger W. ; Heinrich, Ingo ; Monbaron, Michel

In: Dendrochronologia, 2008, vol. 25, no. 3, p. 145-152

Global changes have distinct influence on fluvial processes in torrents causing erosion on slopes and riverbanks even in forested areas. Continuous as well as discontinuous erosion of riverbanks covered by trees frequently results in destabilisation and finally cause the trees affected to tip over. These uprooted trees may lead to a blockage of the river and, in the case of a collapse of the...

Université de Fribourg

Application of ash (Fraxinus excelsior L.) roots to determine erosion rates in mountain torrents

Hitz, Oliver M. ; Gärtner, Holger W. ; Heinrich, Ingo ; Monbaron, Michel

In: Catena, 2008, vol. 72, no. 2, p. 248-258

Due to the effect of global change, the potential risk of natural hazards occurring in alpine areas is expected to increase to an even higher risk-level than has been recorded during the last century. These global changes potentially also have distinct influences on fluvial processes in torrents causing erosion on slopes and riverbanks in forested areas. Dating the time of root exposure along...

Université de Fribourg

Reconstructing spatio-temporal patterns of debris-flow activity using dendrogeomorphological methods

Bollschweiler, Michelle ; Stoffel, Markus ; Ehmisch, Melanie ; Monbaron, Michel

In: Geomorphology, 2007, vol. 87, no. 4, p. 337-351

Debris flows are a major threat in many parts of the Alps, where they repeatedly cause severe damage to infrastructure and transportation corridors or even loss of life. Nonetheless, the spatial behavior of past debris-flow activity and the analysis of areas affected during particular events have been widely neglected in reconstructions so far. It was therefore the purpose of this study to...

Université de Fribourg

400 years of debris flow activity and triggering weather conditions: Ritigraben VS, Switzerland

Stoffel, Markus ; Lièvre, Igor ; Conus, Delphine ; Grichting, Michael A. ; Raetzo, Hugo ; Gärtner, Holger W. ; Monbaron, Michel

In: Arctic Antarctic and Alpine Research, 2005, vol. 37(3), p. 387-395

Three major rainfall events have caused considerable damage in the Valais region (Swiss Alps) since 1987. While important debris flows originating from periglacial environments were recorded during the August 1987 and September 1993 rainfall events, no debris flows occurred in October 2000. This paper aims at putting these large area events and the apparent increase in debris flow frequency into...

Université de Fribourg

Seasonal timing of rockfall activity on a forested slope at Täschgufer (Swiss Alps) – a dendrochronological approach = Saisonale Steinschlagverteilung auf einem bewaldeten Hang im Täschgufer (Schweizer Alpen) – ein dendrochronologischer Ansatz.

Stoffel, Markus ; Lièvre, Igor ; Monbaron, Michel ; Perret, Simone

In: Zeitschrift für Geomorphologie, 2005, vol. 49, no. 1, p. 89-106

La dendrochronologie a été utilisée pour étudier 25 ans d’activités de chutes de pierres sur le versant boisé de Täschgufer, à Täsch (Alpes suisses). Une nouvelle approche, basée sur l’apparition de tissu calleux et de canaux résinifères résultant d’impacts dus à des chutes de pierres, permet de déterminer la saison des événements. Les résultats issus de l’analyse de...

Université de Fribourg

Analyzing rockfall activity (1600–2002) in a protection forest—a case study using dendrogeomorphology

Stoffel, Markus ; Schneuwly, Dominique M. ; Bollschweiler, Michelle ; Lièvre, Igor ; Delaloye, Reynald ; Myint, Moe ; Monbaron, Michel

In: Geomorphology, 2005, vol. 68(3-4), p. 224

For the first time, dendrogeomorphology has been used to investigate spatial and temporal variations of rockfall activity in a protection forest. We report results of 564 cores from 135 severely injured Larix decidua Mill. trees on the west-facing Täschgufer slope, Swiss Alps. While trees sampled reached an age of 297 years on average, the oldest one attained breast height in AD 1318. For...