1. Alpen-Adria Universitaet Klagenfurt; Institute of Social Ecology Vienna, Wien, Graz; Schottenfeldgasse 29; Vienna; 1070; Austria
2. Max-Planck Institute for Biogeochemistry; PO Box 100164; Jena; 07701; Germany
3. Institute of Botany; University of Basel; Basel; 4056; Switzerland
4. Department of Forest Ecosystems and Society; Oregon State University; 321 Richardson Hall; Corvallis; OR; 97331; USA
5. Statistics Norway; PO Box 8131 Dep; Oslo; 0033; Norway
6. Laboratoire des Sciences du Climat et de l'Environnement, IPSL, CEA CNRS UVSQ; Centre d'Etudes Ormes des Merisiers; Gif-sur-Yvette; 91191; France