1. Institute of Landscape Ecology, University of Münster, 48149 Münster, Germany
2. Centre for Integrative Biodiversity Research and Applied Ecology (CIBRA), University of Münster, 48149 Münster, Germany
3. Institute for Bee Protection, Julius Kühn Institute (JKI), Federal Research Centre for Cultivated Plants, 38104 Braunschweig, Germany
4. Department of Ecology, Technische Universität Berlin, 12165 Berlin, Germany