1. Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP), Campo Experimental La Campana, Aldama Chihuahua 32910, Mexico
2. Geography, Geology and Planning Department, Missouri State University, Springfield, MO 65897, USA
3. College of Animal Production and Ecology, Autonomous University of Chihuahua, Chihuahua 31453, Mexico
4. College of Chemistry, Autonomous University of Chihuahua, Chihuahua 31453, Mexico