1. Institute of Ecology, University of Innsbruck, Sternwartestr. 15, 6020 Innsbruck, Austria
2. Department of Biology, University Instelling, Antwerp, B‐2610 Wilrijk, Belgium
3. Max‐Planck Institute for Biogeochemistry, Hans‐Knöll‐Str. 10, 07745 Jena, Germany
4. Institute of Biological and Environmental Sciences, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3UU, UK