1. Unit of Ecology and Evolution; University of Fribourg; Ch. du Musée 10 CH-1700 Fribourg Switzerland
2. Landscape Ecology; Institute of Terrestrial Ecosystems; ETH Zürich; CH-8092 Zürich Switzerland
3. Swiss Federal Research Institute WSL; CH-8903 Birmensdorf Switzerland
4. Department of Ecology and Evolution; University of Lausanne; Biophore; CH-1015 Lausanne Switzerland
5. Institute of Earth Surface Dynamics; University of Lausanne; Géopolis; CH-1015 Lausanne Switzerland
6. Laboratory of Functional Ecology; Institute of Biology; University of Neuchâtel; CH-2000 Neuchâtel Switzerland