1. Department
of Environmental Sciences, University of California, Riverside, California 92521, United States
2. National Park
Service, 47050 Generals Highway, Three Rivers, California 93271, United States
3. Environmental
Change Research Centre, University College London, Gower Street, London WC1E 6BT, U.K.
4. Department
of Geological Sciences, University of Florida, Gainesville, Florida 32611, United States