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Université de Fribourg

Climate change, anthropogenic disturbance and the northward range expansion of Lactuca serriola (Asteraceae)

D'Andrea, Luigi ; Broennimann, Olivier ; Kozlowski, Gregor ; Guisan, Antoine ; Morin, Xavier ; Keller-Senften, Julia ; Felber, François

In: Journal of Biogeography, 2009///doi: 10.1111/j.1365-2699.2008.02060.x

Aim The distribution range of Lactuca serriola, a species native to the summer-dry mediterranean climate, has expanded northwards during the last 250 years. This paper assesses the influence of climate on the range expansion of this species and highlights the importance of anthropogenic disturbance to its spread. Location Central and Northern Europe. Methods Data on the geographic distribution of...

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

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

Evidence of response of vegetation to environmental change on high-elevation sites in the Swiss Alps

Keller, Franciska ; Kienast, F. ; Beniston, Martin

In: Regional Environmental Change, 2000, vol. 1(2), p. 70

Climate change has in the past led to shifts in vegetation patterns; in a future, warmer climate due to enhanced greenhouse-gas concentrations, vegetation is also likely to be highly responsive to such warming. Mountain regions are considered to be particularly sensitive to such changes. In this paper we present an approach to assess the impact of climate change on long-term vegetation plots...

Université de Fribourg

Climate modeling at various spatial and temporal scales : where can dendrochronology help ?

Beniston, Martin

In: Dendrochronologia, 2002, vol. 20, no. 1, p. 117-131

This paper provides a brief overview of certain issues related to climate modeling and the role that dendrochronology can play, and has already played, in this context. Modeling is an essential approach to investigating the future evolution of the climate system in response to human activities. Tree-ring chronologies, on the other hand, have the capability of providing key parameters for...