1. Department of Sustainable Agriculture, Biodiversity and Ecosystem Management, School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
2. Department of Biology, College of Natural and Mathematical Sciences, University of Dodoma, P.O. Box 338, Dodoma, Tanzania
3. Department of Ecology of Tropical Agricultural Systems, Hans-Ruthenberg Institute, University of Hohenheim, Garbenstr. 13, 70599 Stuttgart, Germany
4. Department of Physical Geography, Stockholm University, Stockholm, Sweden