1. West African Science Service Center on Climate Change and Adapted Land Use, University of Lomé, Lomé 01BP1515, Togo
2. Scion (New Zealand Forest Research Institute), Rotorua 3046, New Zealand
3. Center for Development Research, University of Bonn, 53113 Bonn, Germany
4. School of Agriculture, University of Lomé, Lomé 01BP1515, Togo