1. Department of Community Ecology; UFZ - Helmholtz Centre for Environmental Research; Theodor-Lieser-Str. 4 06120 Halle Germany
2. Plant Evolutionary Ecology; University of Tübingen; Auf der Morgenstelle 5 72076 Tübingen Germany
3. Institute of Plant Sciences; University of Bern; Altenbergrain 21 3013 Bern Switzerland
4. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Deutscher Platz 5e D-4103 Leipzig Germany