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The Physical and the Ecological
The Mojave Desert is bordered by three mountain ranges, the Tehachapi to the west and the San Gabriel and San Bernardino ranges to the south. The northern border brushes against the Great Basin steppe while the eastern border is defined by the political border between California and Nevada.
The northern region of the Mojave is known as the high desert with elevations reaching above 600mm in most areas. The desert is essentially three unique regions that vary by elevation from the highest points in the west (900m) to the hill covered the central region that varies between 300m and 1000m with peaks at 2000m and the eastern region that tapers back up to the 2000m level near the California Nevada border. This area is home to several unique plant and animal varieties that occur only within this area.
The western desert is dominated by the Antelope Valley which lies between the San Andreas and Garlock faults. These faults have both raised areas of beautiful red rock at the edges of the valley, one such location is the popular tourist attraction of Red Rock Canyon State Park just north of the town of Mojave. The erratic weather patterns here often prevent the blooming of the poppies that dominate the area.
The central area of the northern Mojave Desert is comprised of various valleys between randomly jutting hills, some reaching as high as 2000m. The valley floors range from 300m to 1000m in parts of Joshua Tree National Park. This region is also home to the Mojave River and supports the most diverse flora and fauna of the entire desert. The only native turtle is the western pond turtle and it now survives only in ephemeral basins and man-made ponds. One of the overflow springs from the river is home to the only surviving wild Mohave tui chub fish.
The east region contains the highest peaks in the desert, topping out at over 2000m. The mountainous ranges in the east desert are responsible for one of the most interesting points in the northern desert, the Kelso Dunes. The formation of the dunes and their relatively secluded location has resulted in the development of several unique species in the Dunes.
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Creosote scrub, a combination of the creosote bush and various low flowering plants is the most prevalent vegetation community in the desert. Joshua trees, as well as several other varieties of Yucca, also cover the entire range of the desert. At the northern edge of the desert Joshua trees begin to blend in with pinyon-juniper woodland. In the far south there are growths of smoke trees, desert willows, and mesquite trees. Several varieties of cactus thrive in the Mojave including the silver cholla, Mojave prickly pear and the barrel cactus.
Probably the most interesting of the flora that inhabit this desert are the short lived flowering plants that are native only to this region. According to the Encyclopedia of Earth, “During favorable years, the region supports more endemic plants per square meter than any location in the United States. Most of these species are winter annuals." These flowering plants invite such insects as the Mojave sooty-wing and painted butterflies.
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There are several distinctive endemic colonies of animals that occur in the Mojave Desert. The Kelso Dunes region houses seven distinct insects including the Kelso Dunes Jerusalem cricket and Kelso Dunes shield back katydid. The desert tortoise is also almost exclusively found in regions of this desert.
Although the following lizard species do extend southward into the Sonora Desert the majority of their range is in the Mojave; LeConte’s thrasher, the banded gecko, the desert iguana, the Mojave chuckwalla, the gila monster and the regal horned lizard.
Lizards may comprise the vast majority of animals in the desert but there are several species of snake also native to the region. The most prominent variety is the rosy boa but there is a very stable population of Mojave patchnose snakes and Mojave rattlesnakes throughout the southern range of the desert.
The mammalian population is actually quite diverse in the southern areas of the desert. Most of the mammals fall into the small to medium rodent categories, but mammals as large as the mountain lion inhabit large portions of the Mojave. Big horn sheep also migrate through the desert and are more of a transitory species. The recent road development in the Mojave has started to change the sheep’s migratory patterns as they try to avoid the traffic of the highways. This is similar to what happened to the antelope of the region when the railroad went through. The once plentiful antelope never recovered and sightings are now rare.
Human intrusion on the Mojave Desert has been minimized by the many state parks in the region as well as the California Desert Protection Act. Although there is much of the desert under protection roughly one half has already been altered by humans for building or farming activities. The current major threat is development of large scale solar arrays. These seemingly “green" technologies will harvest the sunrays that usually feed the native flora and the building process destroys the natural habitat of desert lizards and snakes.
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Mojave Desert Region Physical Geography, http://www.geog.ucsb.edu/~joel/g148_f09/readings/mojave/mojave_desert.html
Encyclopedia of Earth, http://www.eoearth.org/article/Mojave_Desert?topic=49513
Desert Reptiles, http://digital-desert.com/wildlife/reptiles/Desert Mammals, http://digital-desert.com/wildlife/mammals.html%20
photo of Joshua tree by Larry Page on Flickr
photo of Mojave Desert by dsearls on Flickr
photo of solar array by Pink Dispatcher on Flickr