1. Southwest Watershed Research Center, Agricultural Research Service; U.S. Department of Agriculture; Tucson Arizona USA
2. Now at Institute of Space Sciences; Free University of Berlin; Berlin Germany
3. Plant Functional Biology and Climate Change Cluster; University of Technology Sydney; Sydney New South Wales Australia
4. Pasture and Watershed Management Research Unit, Agricultural Research Service, U.S. Department of Agriculture; University Park; Pennsylvania USA
5. Southeast Watershed Research Laboratory; Agricultural Research Service, U.S. Department of Agriculture; Tifton Georgia USA
6. Southern Plains Range Research Station; Agricultural Research Service, U.S. Department of Agriculture; Woodward Oklahoma USA
7. Rocky Mountain Research Station Shrub Sciences Laboratory; Forest Service, U.S. Department of Agriculture; Provo Utah USA
8. Southern Research Station; Forest Service, U.S. Department of Agriculture; Asheville North Carolina USA
9. Crops Research Laboratory, Rangeland Resources Research Unit; Agricultural Research Service, U.S. Department of Agriculture; Fort Collins Colorado USA
10. School of Natural Resources and the Environment; University of Arizona; Tucson Arizona USA
11. Pacific Southwest Research Station; Forest Service, U.S. Department of Agriculture Arcata; California USA
12. Jornada Experimental Range; Agricultural Research Service, U.S. Department of Agriculture; Las Cruces New Mexico USA
13. Jornada Basin Long Term Ecological Research Program; New Mexico State University; Las Cruces New Mexico USA
14. Grazinglands Research Laboratory; Agricultural Research Service, U.S. Department of Agriculture; El Reno Oklahoma USA