1. Environmental Systems Analysis Group; Wageningen University; P.O. Box 47, 6700 AA Wageningen The Netherlands
2. Department of Economics; University of Pretoria; Lynnwood Road Pretoria South Africa
3. CEFE/CNRS (UMR 5175); 34293 Montpellier France
4. Missouri Botanical Garden; 4344 Shaw Boulevard St. Louis MO 63110 U.S.A.
5. Stockholm Resilience Centre; Stockholm University; SE-106 91 Stockholm Sweden
6. Gund Institute for Ecological Economics, 205 B Morrill Hall; University of Vermont; Burlington VT 05405 U.S.A.