Consumer Populations and Their Ecological Impacts Many animal groups play important roles in semi-arid ecosystems, as seed predators and dispersal agents, as herbivores, and as ‘engineers’ through their burrowing or nest-building activities. Composition and abundance of several important consumer groups are monitored regularly in association with the network of 15 permanent plots established to investigate patterns of net primary production. These groups include ground-dwelling arthropods and herps. The Jornada Basin site is also one of the locations of the cross-site Small Mammal Exclosure Study; here, as at the Sevilleta LTER site and the Mapimi Biosphere Reserve in Mexico, plots have been established to observe the effects of excluding cattle, lagomorphs, and small rodents. We are now moving to develop a larger, landscape-scale understanding of animal distributions and impacts during the LTER IV period. The topographic complexity of the Jornada Basin is clearly illustrated in this DEM image. Primary features include the higher elevations of Mount Summerford and the Dona Ana mountains in the southwest, and the San Andres mountain range running north-south along the eastern edge of the basin. The current Rio Grande runs along the western border of the image, but a prehistoric channel of the Rio Grande is reflected in a series of depressions running through the central portion of the basin. Principal Investigators: Athol D. Abrahams (Geography), State University of New York, Buffalo, NY firstname.lastname@example.org Dale Gillette, NOAA, Research Triangle Park, NC email@example.com Vincent P. Gutschick (Biology), New Mexico State University, Las Cruces, NM firstname.lastname@example.org Kris M. Havstad,USDA-ARS Jornada Experimental Range, NM email@example.com Jeffrey E. Herrick, USDA-ARS Jornada Experimental Range, NM firstname.lastname@example.org Laura F. Huenneke (Biology), New Mexico State University, Las Cruces, NM email@example.com David C. Lightfoot (Biology), University of New Mexico, Alburquerque, NM firstname.lastname@example.org H. Curtis Monger (Agronomy), New Mexico State University, Las Cruces, NM email@example.com Anthony J. Parsons (Geography), University of Leicester, UK firstname.lastname@example.org Debra P. C. Peters, USDA-ARS Jornada Experimental Range email@example.com Al Rango, USDA-ARS, Beltsville, MD firstname.lastname@example.org William H. Schlesinger (Botany, Geology), Duke University, Durham, NC email@example.com John Wainwright (Geography), Kings Collge, London, UK firstname.lastname@example.org The Jornada Experimental Range and the Chihuahuan Desert Rangeland Research Center have been the location of hundreds of ecological investigations since 1915. Studies have been carried out under the auspices of USDA, New Mexico State University, the International Biological Programme, and numerous federal agencies, in addition to research performed as part of the LTER program. Locations of some of the primary ongoing studies by LTER and USDA researchers are marked in the map above.