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Université de Fribourg

Evidence of NAO control on subsurface ice accumulation in a 1200 yr old cave-ice sequence, St. Livres ice cave, Switzerland

Stoffel, Markus ; Luetscher, Marc ; Bollschweiler, Michelle ; Schlatter, Frédéric

In: Quaternary Research, 2009, vol. 72, no. 1, p. 16-26

Mid-latitude ice caves are assumed to be highly sensitive to climatic changes and thus represent a potentially interesting environmental archive. Establishing a precise chronology is, however, a prerequisite for the understanding of processes driving the cave-ice mass balance and thus allows a paleoenvironmental interpretation. At St. Livres ice cave (Jura Mountains, Switzerland), subfossil trees...

Université de Fribourg

Tree-ring based reconstruction of the seasonal timing, major events and origin of rockfall on a case-study slope in the Swiss Alps

Schneuwly, Dominique M. ; Stoffel, Markus

In: Natural Hazards and Earth System Sciences, 2008, vol. 8, no. 2, p. 203-211

Tree-ring analysis has been used to reconstruct 22 years of rockfall behavior on an active rockfall slope near Saas Balen (Swiss Alps). We analyzed 32 severely injured trees (L. decidua, P. abies and P. cembra) and investigated cross-sections of 154 wounds.The intra-annual position of callus tissue and of tangential rows of traumatic resin ducts was determined in order to reconstruct the...

Université de Fribourg

Dating past geomorphic processes with tangential rows of traumatic resin ducts

Stoffel, Markus

In: Dendrochronologia, 2008, vol. 25, no. 1, p. 53-60

Past activity of geomorphic processes can be reconstructed on tree-ring series using the presence of injuries, reaction wood or abrupt changes in the annual increment. The analysis of these features provides valuable data on years with process activity. In contrast, an intra-annual dating has so far normally only been possible through the analysis of injuries. In this technical note, it is shown...

Université de Fribourg

Formation and spread of callus tissue and tangential rows of resin ducts in Larix decidua and Picea abies following rockfall impacts

Schneuwly, Dominique M. ; Stoffel, Markus ; Bollschweiler, Michelle

In: Tree Physiology, 2009, vol. 29, no. 2, p. 281-289

After mechanical wounding, callus tissue and tangential rows of traumatic resin ducts (TRDs) are formed in many conifer species. This reaction can be used to date past events of geomorphic processes such as rockfall, debris flow and snow avalanches. However, only few points are known about the tangential spread or the timing of callus tissue and TRD formation after wounding. We analyzed 19 Larix...

Université de Fribourg

Der Fidazer Felssturz von 1939: Analyse & Simulation

Cabernard, Vendelin ; Stoffel, Markus ; Monbaron, Michel

In: Mitteilungen der Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie an der Eidgenössischen Technischen Hochschule Zürich, 2004, vol. 184, p. 1-12

Université de Fribourg

Assessing the vertical distribution and visibility of rockfall scars in trees

Stoffel, Markus

In: Schweizerische Zeitschrift für Forstwesen, 2005, vol. 156(6), p. 195

Rockfall generally consists of individual rocks and boulders moving downslope in a falling, bouncing or rolling motion. As a result, impacts on trees may occur almost anywhere between ground level and several meters above. The present paper therefore focuses on the vertical distribution and the visibility of scars on stem surfaces. Three adult trees from the Altdorfer Bannwald (Altdorf UR, Swiss...

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(1), p. 89-106

Dendrochronology was used to study 25 years of rockfall activity on a forested slope at Täschgufer, Täsch (Swiss Alps). We introduce a new approach by evaluating the initiation of callous tissue and resin duct formation after rockfall occurrence to determine the seasonal timing of events. Results from 270 stem discs of 18 Larix decidua Mill. trees show distinct seasonal differences in rockfall...

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...