1. Department of Geography; University of Exeter; Rennes Drive, Amory Building EX4 4RJ Exeter UK
2. Division of Applied Plant Ecology; Institute for Conservation Research; San Diego Zoo Global; Escondido CA 92027 USA
3. USDA Forest Service; Pacific Northwest Research Station; 1401 Gekeler Lane La Grande OR 97850 USA
4. Eastern Oregon Agriculture and Natural Resource Program; Oregon State University; La Grande OR 97850 USA