1. University of Helsinki, Faculty of Bio- and Environmental Sciences, Department of Environmental Sciences, Urban Ecology Research Group, FI-00014 Helsinki, P.Box 65, Viikinkaari 2, Finland
2. MTA-ELTE-MTM, Ecology Research Group, Biological Institute, Pázmány Péter sétány 1C, H-1117 Budapest, Hungary
3. Department of Agroecology, Aarhus University, Flakkebjerg Research Centre, DK-4200 Slagelse, Denmark