1. Institute of Geography; University of Bayreuth; 95440 Bayreuth Germany
2. Science Domain 6; ICRAF (World Agroforestry Center); 00100 Nairobi Kenya
3. Institut des Sciences de l'Environnement; Université Cheikh Anta Diop; BP 5005 Dakar Senegal
4. Centre de Suivi Ecologique; BP 15532 Dakar-Fann Senegal
5. Campus Arlon Environnement; Université de Liege; Liege Belgique
6. Global Ecology Unit; CREAF; Cerdanyola del Vallès E-08193 Catalonia Spain
7. UMR 1114; INRA-EMMAH; Site Agroparc F-84914 Avignon France
8. BAYCEER; University of Bayreuth; 95440 Bayreuth Germany
9. Department of Geosciences and Natural Resource Management; University of Copenhagen; 1350 Copenhagen Denmark