1. Experimental Plant Ecology; Institute for Botany and Landscape Ecology; Greifswald University; Soldmannstraße 15 D-17487 Greifswald Germany
2. Plant Ecology, Bayreuth; Center of Ecology and Environmental Research (BayCEER); University of Bayreuth; Universitaetsstr. 30 95447 Bayreuth Germany
3. Institute of Ecology; University of Innsbruck; Sternwartestr. 15 6020 Innsbruck Austria
4. Department of Biology; University of York; Heslington York YO10 5DD UK
5. Max Planck Institute for Biogeochemistry; Biogeochemical Integration Department; Hans Knöll Straße, 10 Jena Germany
6. Earth and Life Institute; Université catholique de Louvain; Croix du sud 4/L7.07.04 1348 Louvain-la-Neuve Belgium
7. Department of Geosciences and Natural Resource Management; University of Copenhagen; Rolighedsvej 23 1958 Frederiksberg C Denmark