1. VU University, Institute of Ecological Science; Department of Systems Ecology; de Boelelaan 1085; 1081 HV Amsterdam; The Netherlands
2. Wageningen UR; Department of Soil Physics, Ecohydrology and Groundwater Management; Droevendaalsesteeg 4; 6708 PB Wageningen; The Netherlands
3. Research Institute for Nature and Forest; Kliniekstraat 25; 1070 Brussels; Belgium