1. Physiological Ecology Group, Terrestrial Ecology Section, Department of Biology University of Copenhagen Universitetsparken 15 DK‐2100 Copenhagen Ø Denmark
2. Department of Bioscience Aarhus University Frederiksborgvej 399 4000 Roskilde Denmark
3. Center for Permafrost, University of Copenhagen Øster Voldgade 10 DK‐1350 Copenhagen K Denmark