1. Community Ecology Unit, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
2. School of Architecture, Civil and Environmental Engineering ENAC, École Polytechnique Fédérale de Lausanne EPFL, Station 2, 1015 Lausanne, Switzerland
3. Department of Ecology, Montana State University, 1156-1174 S 11th Ave, Bozeman, MT 59717, USA
4. CEAM Foundation, Joint Research Unit University of Alicante-CEAM, Dept Ecology, University of Alicante, Carr. de San Vicente del Raspeig, PO Box 99, 03080 Alicante, Spain