1USDA-Agricultural Research Service, Great Basin Rangelands Research Unit, 920 Valley Road, Reno, NV 89512, USA
2USDA-Agricultural Research Service, Southwest Watershed Research Center, 2000 E. Allen Rd. Tucson, AZ 85719, USA
3Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, USA