1. Department of Environmental Science, Policy and Management, 151, Hilgard Hall, University of California, Berkeley, CA 94720, USA,
2. Manaaki Whenua‐Landcare Research, PO Box 69, Lincoln, New Zealand,
3. Faculty of Agricultural Sciences, University of British Columbia, 139–2357 Main Mall, Vancouver, BC, Canada V6T 1Z4 ,
4. Institute of Ecology and Resource Management, Schools of Forestry and Ecological Science, University of Edinburgh, Darwin Building, King's Buildings, Mayfield Rd, Edinburgh EH9 3JU, UK