1. Landscape Ecology Group; University of Oldenburg; Oldenburg; 26111; Germany
2. Laboratoire d'Ecologie Alpine (CNRS UMR 5553) and Station Alpine Joseph Fourier (UMS-UJF-CNRS 2925); Université Joseph Fourier; BP 53; Grenoble Cedex 09; F-38042; France
3. The James Hutton Institute; Craigiebuckler; Aberdeen; AB15 8QH; UK