1 Institute of Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia; peter.bridgewater@canberra.edu.au.
2 Division of Ecological Sciences, United Nations Educational, Scientific and Cultural Organization, 75007 Paris, France.
3 Agricultural Research for Development, French Agricultural Research Centre for International Development, 75116 Paris, France.
4 International Co-ordinating Council of the Man and the Biosphere Programme, United Nations Educational, Scientific and Cultural Organization, 75007 Paris, France.