1. UBC School of Public Policy and Global Affairs and Institute for Resources, Environment and Sustainability, University of British Columbia, Vancouver, British Columbia V6T 1Z2, Canada;
2. Commonwealth Scientific and Industrial Research Organization, Agriculture and Food, St. Lucia, Queensland 4067, Australia
3. Department of Environmental Science, Policy and Management, University of California Berkeley, California 94720-3114, USA
4. Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada