Desert National Wildlife Refuge is located in the northeastern portion of the Mojave Desert in northwestern Clark County and southwestern Lincoln County in southern Nevada. At over 1,600,000 acres in size, it is the largest National Wildlife Refuge in the lower 48 states. Lying within the "U" formed by U.S. Highway 93 on the east and Interstate 15 and U.S. Highway 95 on the south, its southern boundary is only about one-half mile from the northern city limits of metropolitan Las Vegas.
The Refuge encompasses six major mountain ranges, running generally north to south and separated by relatively flat and narrow alluvial valleys. The mountain crests are flanked by numerous drainages with rock-strewn bottoms, steep walls, and narrow side canyons. Portions of several valley floors consist of large dry lake beds or "playas." Transitional areas of smaller mountains and slopes "bajadas" angle downward from the bases of the main mountain ranges toward the valley floors and are cut by many deep gullies or washes. The valleys appear smooth at a distance, but contain numerous washes with sharply cut banks and large boulders. Elevations range from 3,000 feet at the Corn Creek Field Station to 9,900 feet atop Hayford Peak.
The predominant habitat type on Desert NWR is desert shrub, characterized by creosote bush (Larrea tridentata) communities (2,600 to 4,200 feet in elevation) and blackbush (Coleogyne ramosissima) communities (4,200 to 6,000 feet in elevation). Mohave yucca (Yucca schidigera) and Joshua Tree ( Yucca brevifolia) are common throughout the blackbush community. Desert almond (Prunus fasciculata), Apache Plume (Fallugia paradoxa), and Mexican bladder sage (Salazaria mexicana) are found in the dry washes that bisect this habitat type. Grasses include Indian ricegrass (Oryzopsis hymenoides), squirreltail ( Elymus elymoides), fluff grass (Erioneuron pulchellum), big galleta (Hilaria rigida), and red brome (Bromus rubens). Cacti include barrel cactus (Ferocactus cylindraceus), prickly pear (Opuntia erinacea), beavertail (Opuntia basilaris), and various species of cholla (Opuntia spp.).
The woodland habitat type occurs between 6,000 and 7,400 feet in elevation. It is primarily comprised of pinon pine (Pinus monophulla) and Utah juniper (Juniperous osetosperma), with yellow pine (Pinus ponderosa) and white fir (Abies concolor) common at the upper extremes. Sagebrush (Artemisia spp.) is often codominant. Shrubs include Apache plume (Fallugia paradoxa), Mormon tea (Ephedra nevadensis), mountain-mahogany (Cercocarpus betuloides), and serviceberry (Amerlanchier utahensis).
The coniferous forest habitat type is comprised of the fir-pine community (7,500 to over 9,000 feet in elevation) and the bristlecone pine (Pinus longaeva) community (generally above 9,000 feet.) Within the fir-pine community, yellow pine is more abundant in canyon bottoms and protected slopes and white fir is more abundant at higher elevations. On steep north and east facing slopes, bristlecone pine can extend down to 8,500 feet.
The pseudo-alpine habitat is scarce and only occurs on the south and west facing slopes of Hayford and Sheep Peaks above 9,500 feet. It is comprised entirely of black sagebrush (Artemisia spp.).
Desert National Wildlife Refuge was established for the conservation of the desert bighorn sheep (Ovis canadensis nelsoni) in its natural environment. The primary management objective is to protect the desert bighorn sheep and other native wildlife habitat from disturbance. Because low elevational refuge rainfall averages only four and one-half inches per year, where appropriate, springs have been developed and rainwater catchments have been constructed to ensure wildlife dependable water supplies during critical periods of drought and heat. Enhancement projects such as these reduce competition for food, water, and cover, plus reduce crowding or vulnerability to predation and disease. Improving and maintaining these facilities to ensure they are in working order is done on a continuous and routine basis.
In 1974, approximately 1,433,100 acres of land within Desert National Wildlife Refuge were proposed for wilderness designation under the Wilderness Act of 1964. Since that time, the refuge has been managed as "de facto" wilderness so as to retain the primitive character which initially made it eligible for inclusion within the National Wilderness Preservation System. Designated roads within the refuge are few in number and primitive in condition. All vehicles must remain on these roads and access to remote areas is by foot or horseback. Helicopters are used to conduct bighorn sheep surveys and to ferry people, supplies, and equipment to otherwise inaccessible work sites. Because the lands are to be "affected primarily by the forces of nature" prescribed fire has not been used as a management tool and wildfires are closely monitored to be sure they do not threaten human lives or property. Habitat management primarily involves restoration of disturbed areas. This includes planting native vegetation, cleaning up dump sites, erecting barricades to deter off-road vehicle use, and educating the public.
The Nellis Air Force Range (NAFR) overlays 846,000 acres of the Refuge, and has been used since 1940 for testing armament and for training pilots in aerial warfare. The U.S. Air Force is authorized to have primary use of NAFR, but only in accordance with the Refuge Administration Act. Basic wildlife and habitat management activities on that portion of the refuge are somewhat hampered by Air Force safety and security needs.