1. Chairgroup Land Dynamics, Environmental Sciences Group; Wageningen University; Droevendaalsesteeg 3; 6708 PB; Wageningen; The Netherlands
2. Physical and Regional Geography Research Group; K.U. Leuven, GEO-Institute; Celestijnenlaan 200E; B-3001; Heverlee; Belgium
3. Faculty of Geo-Information Science and Earth Observation; University of Twente; PO Box 217; 7500 AE; Enschede; The Netherlands