Chihuahuan Desert

Chihuahuan Desert
Chihuahuan desert landscape in Big Bend National Park
Location map of Chihuahuan Desert
Ecology
Realm	Nearctic
Biome	Deserts and xeric shrublands
Borders	List Edwards Plateau savanna Meseta Central matorral Sierra Madre Occidental pine–oak forests Sierra Madre Oriental pine–oak forests Sonoran Desert Tamaulipan matorral Tamaulipan mezquital Western short grasslands
Geography
Area	501,896 km2 (193,783 sq mi)
Countries	Mexico United States
States	List Chihuahua Coahuila Durango Nuevo León Sonora Zacatecas Arizona New Mexico Texas
Coordinates	30°32′26″N 103°50′14″W / 30.54056°N 103.83722°W / 30.54056; -103.83722
Oceans or seas	Non
Rivers	hot semi-arid (BSh)
Conservation
Conservation status	Vulnerable
Global 200	Yes
Protected	35,905 km2 (13,863 sq mi) (7%)[1]

The Chihuahuan Desert (Spanish: Desierto de Chihuahua, Desierto Chihuahuense) is a desert ecoregion designation covering parts of northern Mexico and the southwestern United States. It occupies much of far West Texas, the middle to lower Rio Grande Valley and the lower Pecos Valley in New Mexico, and a portion of southeastern Arizona, as well as the central and northern portions of the Mexican Plateau. It is bordered on the west by the Sonoran Desert, the Colorado Plateau, and the extensive Sierra Madre Occidental range, along with northwestern lowlands of the Sierra Madre Oriental range. Its largest, continual expanse is located in Mexico, covering a large portion of the state of Chihuahua, along with portions of Coahuila, north-eastern Durango, the extreme northern part of Zacatecas, and small western portions of Nuevo León. With an area of about 501,896 km² (193,783 sq mi),^[1] it is the largest hot desert in North America.^[2] The desert is fairly young, existing for only 8000 years.^[3]

Geography

There are several larger mountain ranges in the Chihuahuan Desert, including the Sierra Madre, the Sierra del Carmen, the Organ Mountains, the Franklin Mountains, the Sacramento Mountains, the Chisos Mountains, the Guadalupe Mountains, and the Davis Mountains. These create "sky islands" of cooler, wetter, climates adjacent to, or within the desert, and such elevated areas have both coniferous and broadleaf woodlands, including forests along drainages and favored exposures. The lower elevations of the Sandia–Manzano Mountains, the Magdalena–San Mateo Mountains, and the Gila Region partly border the Chihuahuan Desert and partly border other ecoregions that are not deserts.

There are few urban areas within the desert: the largest is

According to the World Wide Fund for Nature the Chihuahuan Desert may be the most biologically diverse desert in the world as measured by species richness or endemism. The region has been badly degraded, mainly due to grazing.^[4] Many native grasses and other species have become dominated by woody native plants, including creosote bush and mesquite, due to overgrazing and other urbanization. The Mexican wolf, once abundant, was nearly extinct and remains on the endangered species list.^[5]

Climate

The desert is mainly a

Owing to its inland position and higher elevation than the Sonoran Desert to the west, mostly varying from 480 to 1,800 m (1,575 to 5,906 ft) in elevation,^[7] the desert has a slightly milder climate in the summer (though usually daytime June temperatures are in the range of 32 to 40 °C or 90 to 104 °F), with mild to cool winters and occasional to frequent freezes.^[6] The hottest temperatures in the desert occur in lower elevation areas and valleys, including near the Rio Grande from south of El Paso into the Big Bend, and the Bolson de Mapimi.^[7] A subtropical temperature regime describes lower elevations in the Texas Big Bend region up to the Presidio and Candelaria areas, then southward into similar elevations, while a warm temperate temperature regime describes higher elevations and further north. The average annual temperature in the desert varies from about 13 to 22 °C (55 to 72 °F), depending on elevation and latitude.

The mean annual precipitation for the Chihuahuan Desert is 235 mm (9.3 in) with a range of approximately 150–400 mm (6–16 in), although it receives more precipitation than most other warm desert ecoregions.^[3] Nearly two-thirds of the arid zone stations have annual totals between 225 and 275 mm (8.9 and 10.8 in).^[8] Snowfall is scant except at the higher elevation edges. Northern and eastern portions have more definite winters than southern and western portions, receiving a portion of winter precipitation as snowfall most winters.^[6]

Flora

The creosote bush (Larrea tridentata) is the dominant plant species on gravelly and occasional sandy soils in valley areas within the Chihuahuan Desert. The other species found with creosote bush depend on factors including the soil type, elevation, and degree of slope. Viscid acacia (Vachellia vernicosa), and tarbush (Flourensia cernua) dominate northern portions, while broom dalea (Psorothamnus scoparius) occurs on sandy soils in western portions. Yucca and Opuntia species are abundant on slopes and uplands in most areas, while Arizona rainbow cactus (Echinocereus polyacanthus) and Mexican fire-barrel cactus (Ferocactus pilosus) inhabit portions near the US–Mexico border.

The United Nations Environment Programme reported in 2006 that nearly half of the bird, mammal, and butterfly species in the Chihuahuan Desert are expected to be replaced by other species by 2055 due to climate change.[9]

Protected areas

A 2017 assessment found that 35,905 km² (13,863 sq mi), or 7%, of the ecoregion is in protected areas.

• 
  Young creosote bush (Larrea tridentata)
• 
  Yucca, creosote, buffalo gourd, and mesquite typify the plants in the Chihuahuan Desert
• 
  Lechuguilla (Agave lechuguilla)—one of the indicator plants of the Chihuahuan Desert
• 
  Poza Azul, one of many a springs in the

  Cuatro Ciénegas Basin in central Coahuila

  , Mexico (2009).

References

External links

Wikimedia Commons has media related to Chihuahuan Desert.

• "Chihuahuan desert". Terrestrial Ecoregions. World Wildlife Fund.
• Chihuahuan Desert images at bioimages.vanderbilt.edu (slow modem version)
• Pronatura Noreste in the Chihuahuan Desert^{[permanent dead link]}
• Small desert beetle found to engineer ecosystems EurekAlert! March 27, 2008