Claude Raynaut is a Researcher at the National Centre for Scientific Research (CNRS), Bordeaux, France; Philippe Lavigne Delville is a Researcher at the Research and Study Group on Techniques (GRET), France; Jean Koechlin is a Professor of Biogeography, Michel Montaigne University, Bordeaux, France; Pierre Janin is a Researcher at the French Institute for Development in Cooperation (ORSTOM), France; Emmanuel Grégoire is a Researcher at the National Centre for Scientific Research (CNRS), Bordeaux, France.