1. University of Antwerp, Department of Biology, Ecosystem Management Research Group, Universiteitsplein 1C, B-2610 Wilrijk, Belgium.
2. Cary Institute of Ecosystem Studies, Millbrook, NY, USA.
3. Yale University, Department of Ecology and Evolutionary Biology, New Haven, CT, USA.
4. Botanic Garden Meise, Nieuwelaan 38, 1860 Meise, Belgium.
5. Department of Geosciences, Swedish Museum of Natural History, Box 50007, Stockholm, Sweden.
6. Section 3.3 Earth Surface Geochemistry, GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany.