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Université de Fribourg

Changes in wood anatomy in tree rings of Pinus pinaster Ait. following wounding by flash floods

Ballesteros, J.A. ; Stoffel, Markus ; Bodoque, J.M. ; Bollschweiler, Michelle ; Hitz, Oliver ; Díez-Herrero, A.

In: Tree-Ring Research, 2010, vol. 66, no. 2, p. 93-103

This paper analyzes the anatomical response of Pinus pinaster Ait. following wounding by flash floods. A total of 14 wood samples were taken from 14 different scarred trees located on the river banks of the Arroyo Cabrera torrent (Spanish Central System). In addition, 20 increment cores were collected from undisturbed and healthy P. pinaster trees to build a local reference chronology. For the...

Université de Fribourg

Tree-ring reconstruction of past lahar activity at Popocatépetl volcano, Mexico

Bollschweiler, Michelle ; Stoffel, Markus ; Vázquez Selem, Lorenzo ; Palacios, David

In: The Holocene, 2010, vol. 20, no. 2, p. 265-274

Lahars represent a major threat on the slopes of volcanoes all over the world. In order to realistically assess hazards, knowledge on the occurrence and timing of past lahar activity is of crucial importance. However, archival data on past events is usually scarce or completely missing. Tree-ring records have repeatedly proved to be a reliable data source for the reconstruction of past...

Université de Fribourg

Tree-ring reconstruction of past debris flows based on a small number of samples—possibilities and limitations

Stoffel, Markus ; Bollschweiler, Michelle

In: Landslides, 2009, vol. 6, no. 3, p. 225-230

Tree-ring analyses have often been used in the past for the reconstruction of spatiotemporal patterns of previous debris-flow activity, often yielding very precise and extensive data for torrents where information on former activity was largely missing. Unless dendrogeomorphology is slated for multimillion Euro developments, the large sets of tree-ring series that are usually used in these...

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 analysis in natural hazards research – an overview

Stoffel, Markus ; Bollschweiler, Michelle

In: Natural Hazards and Earth System Sciences, 2008, vol. 8, no. 2, p. 187-202

The understanding of geomorphic processes and knowledge of past events are important tasks for the assessment of natural hazards. Tree rings have on varied occasions proved to be a reliable tool for the acquisition of data on past events. In this review paper, we provide an overview on the use of tree rings in natural hazards research, starting with a description of the different types of...

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...