Sonoran Desert

Map of the Mojave and Sonoran deserts.

Mountains in the Sonoran Desert

The Sonoran Desert (sometimes called the Gila Desert after the Gila River or the Low Desert in opposition to the higher Mojave Desert) is a North American desert which straddles part of the United States-Mexico border and covers large parts of the U.S. states of Arizona and California and the northwest Mexican states of Sonora, Baja California, and Baja California Sur. It is one of the largest and hottest deserts in North America, with an area of 311,000 square kilometres (120,000 sq mi). The desert contains a variety of unique plants and animals, such as the saguaro cactus.

Location

The Sonoran Desert wraps around the northern end of the Gulf of California, from northeastern Baja California Sur north through much of Baja California Norte through southeastern California and southwestern Arizona to western part of Sonora. It is bounded on the west by the Peninsular Ranges, which separate it from the California chaparral and woodlands and Baja California desert ecoregions of the Pacific slope. To the north, the Sonoran Desert transitions to the colder-winter Mojave, Great Basin, and Colorado Plateau deserts. To the east, the deserts transition to the coniferous Arizona Mountains forests and Sierra Madre Occidental forests at higher elevations. The Sonoran-Sinaloan transition subtropical dry forest marks the transition from the Sonoran Desert to the tropical dry forests of Sinaloa to the south.

The desert's sub-regions include the Colorado Desert and Yuma Desert. In the 1957 publication, Vegetation of the Sonoran Desert, Forrest Shreve divided the Sonoran Desert into seven regions according to characteristic vegetation: Lower Colorado Valley, Arizona Upland, Plains of Sonora, Foothills of Sonora, Central Gulf Coast, Vizcaíno Region, and Magdalena Region. (see An Overview of the Sonoran Desert, external link below). Many ecologists now consider Shreve's Vizcaíno and Magdalena regions, which lie on the western side of the Baja California Peninsula, to be a separate ecoregion, the Baja California desert.

Sonoran Desert near Maricopa, Arizona

Ecology

The Sonoran Desert includes 60 mammal species, 350 bird species, 20 amphibian species, 100+ reptile species, 30 native fish species, over 1000 native bee species, and more than 2000 native plant species. The Sonoran Desert area southwest of Tucson and near the Mexican border is vital habitat for the only population of Jaguars living within the United States.

Flora

Many plants not only survive the harsh conditions of the Sonoran Desert, but they actually thrive. Many have evolved to have specialized adaptations to the desert climate. The Sonoran Desert's biseasonal rainfall pattern results in more plant species than in the other North America deserts. The Sonoran Desert includes such plants from the agave family, palm family, cactus family, legume family, and many others.

Sonoran Desert near Tucson, AZ in December

The Sonoran is the only place in the world where the famous saguaro cactus grows in the wild. Cholla, beavertail, hedgehog, fishhook, prickly pear, night blooming cereus, and organ pipe are other species of cactus found here. Cactus provide food and homes to many desert mammals and birds, with showy flowers in reds, pinks, yellows, and whites blooming most commonly from late March through June, depending on the species and seasonal temperatures.

Creosote bush and bur sage dominate valley floors. Indigo bush, Mormon tea, and mesquite are other shrubs that may be found. Wildflowers include desert sand verbena, desert sunflower, and evening primroses. Ascending from the valley up bajadas, various subtrees such as palo verde, ironwood, desert willow, and crucifixion thorn are common, as well as multi-stemmed ocotillo. Shrubs found at higher elevations include whitethorn acacia, fairy duster, and jojoba. In the desert subdivisions found on Baja California, cardon cactus, elephant tree, and boojum tree occur.^[1] The California Fan Palm is also found in parts of the Sonoran Desert, including areas of the Anza Borrego Desert State Park.^[2]

Human population

The Sonoran Desert is home to seventeen aboriginal American cultures^{[citation needed]}.

The largest city in the Sonoran Desert is Phoenix, United States, with a 2008 metropolitan population of about 4.3 million.^[3] Located on the Salt River in central Arizona, it is one of the fastest-growing metropolitan areas in the United States. In the Phoenix area, desert is losing ground to urban sprawl at a rate of approximately 4,000 square metres (0.99 acres) ) per hour.^[4]

The next largest cities are Tucson, in southern Arizona, U.S.A., with a metro area population of around 1 million,^[3] and Mexicali, Baja California, Mexico, whose municipality also has a population of around 900,000. The municipality of Hermosillo, Sonora, Mexico has a population of around 700,000. Ciudad Obregon, Sonora, Mexico in the southern part of the desert has a population of 375,800. ^[5][6]

Conservation

On January 17, 2001, 2,008 square kilometres (496,000 acres) of the Sonoran Desert in Arizona was set aside as the Sonoran Desert National Monument for the purpose of enhancing resource protection.^[7]

References

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (October 2007)

See also

Wikimedia Commons has media related to: Sonoran Desert

• List of deserts by area
• List of plants by common name (Sonoran Desert)
• Communities in the Sonoran Desert
• Fauna of the Sonoran Desert
• Mountain Ranges of the Sonoran Desert
• Sonoran Desert National Monument
• Spanish missions in the Sonoran Desert
• List of Sonoran Desert birds (Arizona)
• Yuma Desert
• Chihuahuan Desert
• Mojave Desert

External links

• Arizona-Sonora Desert Museum

• Sonoran Desert and its subdivisions, with map and photos

• Timeline of the Sonoran desert
• An Overview of the Sonoran Desert, by William G. McGinnies
• The Sonoran Desert Naturalist
• Very short overview of Sonoran Desert Geology
• Map of the Sonoran Desert
• Sonoran desert (World Wildlife Fund)
• Sonoran Desert images at bioimages.vanderbilt.edu (slow modem version)

Links to parks and recreational areas within the Sonoran Desert

• Saguaro National Park Page
• South Mountain Park / Preserve

Coordinates: 32°15′36″N 112°55′34″W / 32.26°N 112.92611°W / 32.26; -112.92611