1. Institute for Environmental Science; University of Leiden; 2333 CC Leiden The Netherlands
2. Soil and Ecosystem Ecology Group; University of Manchester; Michael Smith Building Oxford Road M13 9PT Manchester UK
3. Community and Conservation Ecology; University of Groningen; P.O. Box 11103 9700 CC Groningen The Netherlands
4. Institute of Plant Sciences; University of Bern; Altenbergrain 21 3013 Bern Switzerland
5. Senckenberg Gesellschaft für Naturforschung; Biodiversity and Climate Research Centre BIK-F; Senckenberganlage 25 60325 Frankfurt Germany
6. Section Animal Ecology; Department of Ecological Sciences; Vrije Universiteit Amsterdam; De Boelelaan 1085 1081 HV Amsterdam The Netherlands