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Université de Fribourg

Gap‐filling algorithm for ground surface temperature data measured in permafrost and periglacial environments

Staub, Benno ; Hasler, Andreas ; Noetzli, Jeannette ; Delaloye, andReynald

In: Permafrost and Periglacial Processes, 2017, vol. 28, no. 1, p. 275–285

Ground surface temperatures (GST) are widely measured in mountain permafrost areas, but their time series data can be interrupted by gaps. Gaps complicate the calculation of aggregates and indices required for analysing temporal and spatial variability between loggers and sites. We present an algorithm to estimate daily mean GST and the resulting uncertainty. The algorithm is designed to...

Université de Fribourg

Internal structure and permafrost distribution in two alpine periglacial talus slopes, Valais, Swiss Alps

Scapozza, Cristian ; Lambiel, Christophe ; Baron, Ludovic ; Marescot, Laurent ; Reynard, Emmanuel

In: Geomorphology, 2011, vol. 132, no. 3-4, p. 208-221

In order to determine the spatial extension and the characteristics of permafrost within alpine talus slopes, two sites located in the western part of the Swiss Alps were studied using borehole drilling and electrical resistivity tomography (ERT) profiles. Three boreholes were drilled along an upslope–downslope transect in both talus slopes. In both sites, frozen sediments are present only in...

Université de Fribourg

Unraveling the patterns of late Holocene debris-flow activity on a cone in the Swiss Alps: chronology, environment and implications for the future

Stoffel, Markus ; Conus, Delphine ; Grichting, Michael A. ; Lièvre, Igor ; Maître, Gilles

In: Global and Planetary Change, 2008, vol. 60, no. 3-4, p. 222-234

Debris-flow activity on the forested cone of the Ritigraben torrent (Valais, Swiss Alps) was assessed from growth disturbances in century-old trees, providing an unusually complete record of past events and deposition of material. The study of 2246 tree-ring sequences sampled from 1102 Larix decidua Mill., Picea abies (L.) Karst. and Pinus cembra ssp. sibirica trees allowed reconstruction of 123...

Université de Fribourg

Assessing the protective effect of mountain forests against rockfall using a 3D simulation model

Stoffel, Markus ; Wehrli, André ; Kühne, Roderick ; Dorren, Luuk K.A. ; Perret, Simone ; Kienholz, Hans

In: Forest Ecology and Management, 2006, vol. 225, p. 1-3

We used one of the few rockfall models explicitly taking trees into account and compared the results obtained with the 3D simulation model RockyFor with empirical data on tree impacts at three mountain forests in Switzerland. Even though we used model input data with different resolutions at the study sites, RockyFor accurately predicted the spatial distribution of trajectory frequencies at all...

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...