A Diverse Desert
Shared by two nations, the Chihuahuan Desert Ecoregion is isolated from adjacent arid regions by two mountain ranges, the Sierra Madre Occidental to the west and the Sierra Madre Oriental to the east. About 9,000 years ago, this area was wetter and the mountain slopes were dominated by forests. As the area became more dry, species experienced isolation, differentiation, and sometimes extinction which led to the unique Chihuahuan flora and fauna of today.
Deserts, by their very name, are seldom regarded as important reservoirs of biological diversity, but some deserts are extraordinarily rich in species, rare plants and animals, specialized habits, and unique biological communities. The Chihuahuan Desert is considered the most diverse desert in the Western Hemisphere and one of the most diverse arid regions in the world. Unfortunately, the Chihuahuan Desert Ecoregion is also one of the most endangered regions in the world. Overgrazing, water depletion and diversion, changes in the fire regime, urbanization, increases in agricultural and resource extraction activities, invasive exotic species, and overcollecting of native plants and animals are among the greatest threats to biodiversity in the Ecoregion.
The Chihuahuan Desert Ecoregion covers nearly 647,500 square kilometers (250,000 square miles), with over 90% of its area within the nation of Mexico. It is the largest desert in North America, extending nearly 1,500 km from south of Albuquerque, New Mexico to 250 km north of Mexico City. Parts of the Mexican states of the Chihuahua, Coahuila, Durango, Zacatecas, Nuevo León, and San Luis Potosí, as well as the southeastern corner of Arizona and large parts of New Mexico and the Trans-Pecos region of Texas lie within the Chihuahuan Desert Ecoregion.
Climate and Topography
The Chihuahuan desert differs from the Sonoran and Mojave deserts because it receives more summer rain during monsoon thunderstorms and has colder winters. The climate includes hot summers and cool to cold, dry winters. Annual precipitation ranges from 150 to 500 mm (approximately 6 to 20 inches), with a large part of the rain falling in the form of monsoonal rains during the summer months. The basin and range topography of the Chihuahuan Desert consists of broad desert valleys (basins) bordered by terraces, mesas, and mountains (ranges). Salt lakes or playas can form because rainwater drains internally in these closed basins. Dune fields composed of quartz or gypsum sand are also common.
Flora and Fauna
The eastern boundary of the Chihuahuan Desert is one of the oldest and richest centers of plant evolution on the North American continent. A wide variety of vegetation communities are present in the in the ecoregion, ranging from desert shrublands at lower elevations and conifer woodlands at the highest elevations. The Chihuahuan Desert boasts as many as 3,500 plant species, including nearly a quarter of the world’s cactus species. Approximately 1,000 of the plant species grow only in this ecoregion. Some distinctive habitat types in the Chihuahuan Desert include yucca woodlands, playas, gypsum dunes, and a diverse array of freshwater habitats. Vast desert grasslands and a wide variety of yuccas and agaves, including many endemic species, also make this desert extremely unique.
The Chihuahuan Desert is home to more than 170 species of amphibians and reptiles. At least 18 of these species are endemic to the Ecoregion. There are a surprisingly large number of endemic fish that occur in the Chihuahuan Desert as well—nearly half of the 110 fish species in the region are either endemic or of limited distribution. Most are relic species found in isolated springs in the closed basins.
The Chihuahuan Desert supports a large number of wide-ranging mammals (more than 130 species) such as the mule deer, pronghorn, jaguar, javelina, and grey fox. It harbors North America's largest remaining black-tailed prairie dog complex on the continent and the only populations of the endemic Mexican prairie dog. Historically, the Chihuahuan Desert was one of the few ecoregions where grizzly bears, wolves, and jaguars could be found at the same locality. Several sites still retain a remaining complement of larger vertebrates, including mountain lions, jaguars, and Golden eagles.
The Ecoregion supports around 400 bird species comprised mostly of widespread and common species with few endemics. The Chihuahuan Desert grasslands serve as wintering grounds for a large proportion of North American Great Plains birds including a number of significantly declining species such as mountain plover, ferruginous hawk, and Baird’s sparrow. Neotropical migratory birds utilize riparian corridors along the Pecos and Rio Grande rivers.
Last updated: September 20, 2018