1. Terrestrial Ecology Research Group, Department for Ecology and Ecosystem Management, School of Life Sciences Weihenstephan; Technische Universität München; Hans-Carl-von-Carlowitz-Platz 2 D-85354 Freising Germany
2. International Institute for Tropical Agriculture (IITA); Main Road IRAD, Nkolbisson, PO Box 2008 (Messa) Yaoundé Cameroon