1. Center for International Forestry Research (CIFOR), Central Africa Regional Office, Yaound, Cameroon; Crawford School of Economics and Government, The Australian National University (ANU), Canberra, Australia.
2. Center for International Forestry Research (CIFOR), Central Africa Regional Office, Yaound, Cameroon; Centre de Coopration Internationale en Recherche Agronomique pour le Dveloppement (CIRAD), TA 10/D, 34398 Montpellier cedex 5, France.
3. Center for International Forestry Research (CIFOR), Central Africa Regional Office, Yaound, Cameroon.
4. Crawford School of Economics and Government, The Australian National University (ANU), Canberra, Australia.