1. Department of Systematic Zoology Faculty of Biology Adam Mickiewicz University in Poznań Umutlowska 89 61‐614 Poznań Poland
2. Department of Agricultural, Forest and Food Sciences University of Turin 10095 Grugliasco Torino Italy
3. Department of Geography and Planning School of Environmental Sciences University of Liverpool Liverpool UK
4. Lab of Ornithology Cornell University Ithaca NY 14850 USA
5. Fort Collins Science Center U.S. Geological Survey Fort Collins CO USA
6. Institute of Forest Ecology Department of Forest and Soil Sciences University of Natural Resources and Life Sciences Vienna Austria
7. Department of Biology Faculty of Science Kyushu University 819‐0395 Fukuoka Japan
8. School of Life Sciences Keele University Staffordshire ST5 5BG UK
9. DISAA University of Milan via Celoria 2 20123 Milano Italy
10. Swiss Federal Institute for Forest, Snow and Landscape Research WSL Forest Dynamics, Zürcherstrasse 111CH‐8903Birmensdorf Switzerland
11. Department of Plant Sciences University of Cambridge Downing St Cambridge CB2 3EA UK