The Mojave Desert

The Mojave Desert

Jenna Goren

http://digital-desert.com/regions/

http://www.dfg.ca.gov/wildlife/WAP/statewide-overview.html

The Mojave Desert covers a total of 125,000 square kilometers in southern Nevada, western Arizona, southwestern Utah, and southeastern California.

http://www.arminhornung.de/gallery3/index.php/roadtrip07/joshuatree/joshua_tree_360_panorama
Panoramic View of Joshua Tree National Park (California)

http://www.desertusa.com/du_mojave.html
Death Valley (California)

History

The Mojave Desert is the smallest of the North American desert regions, containing an area of about 125,000 square kilometers. It is often referred to as the “high desert” due to its above 600-meter elevation. The Mojave Desert in California, specifically, can be divided into three sub regions: Antelope Valley (bounded by the Garlock Fault and the San Andreas Fault), the Mojave River Valley (including Joshua Tree National Park), and the East Mojave National Preserve (between the I-40 and I-15). On average, the desert receives about 5 inches of precipitation per year, with May and June being the driest months. Temperatures in the Mojave Desert are mainly determined by elevation, which typically do not vary significantly, resulting in relatively similar temperatures throughout the desert. During the summer, high temperatures range from around 30° Celsius to around 44° Celsius. On the other hand, low temperatures during winter range from about 4° Celsius to about -5° Celsius. Elevation in the Mojave Desert is also related to animal and vegetation types found throughout the desert. These plants and animals are known for being able to survive some of the harshest conditions on Earth. The Mojave Desert has 14 endemic animal species and 29 species federally listed as threatened or endangered.  The most prevalent vegetation existing in the Mojave Desert is the creosote shrub, which occurs at elevations under 1,000 meters. The Joshua tree, occurring between 750 meters and 1,500 meters, is one of the most famous vegetation types in the desert. The Joshua Tree National Park and the East Mojave National Preserve contain particularly well-developed Joshua tree woodlands. Death Valley, in the eastern California region of the Mojave Desert, is a very unique desert valley. It has the lowest elevation in North America, 282 feet below sea level, the second-highest recorded temperature in history, 134° Fahrenheit on July 10, 1913, and is one of the driest locations in North America. Death Valley received its name at the time of the California gold rush in 1849, when many people died trying to cross the valley in search of gold.  

http://www.scribd.com/doc/38896269/The-Nature-Conservancy-s-Mojave-Desert-Ecoregional-Assessment-2010

Human Impact

The Mojave Desert, although one of the least populated areas in the western United States, is a fragile desert ecosystem, susceptible to human impact. Leonard Gaydos, Coordinator for the U.S. Geological Survey’s Recoverability and Vulnerability of Desert Ecosystems project, said, “The Mojave Desert is increasingly viewed as a playground. It now contains four national parks with millions of people around the edges.” It wasn’t always this way; it used to be an escape from civilization. In fact, the U.S. military set up training facilities throughout this open space so they could train in an isolated place without disturbing anyone. Now, the desert is facing an increased demand for the land and impacts from vehicles, grazing livestock, and military activities. On the positive side, society’s viewpoint is beginning to change. In the past, the Mojave Desert has pretty much been overlooked and ignored, but it is starting to gain value in people’s minds. Now, it is receiving more human interest and attention, which is important to the ecosystem’s protection and preservation.

            One of the main environmental problems that this desert, among many others, is facing is windblown dust. While this is certainly a natural occurrence, human activity has only added to this issue. Studies show that windblown dust is likely to affect the physiological performance of desert shrubs as well as reduce the photosynthesis rates of plants affected by dust. It also reduces leaf conductance, transpirations, and water-use efficiency. All of these factors lead to the most important issue: temperature increase. It was found that dusted plants have leaves and stems that are 2-3° Celsius higher as a result of increased infrared radiation. The dusted plants also produce smaller leaf areas, which shows that production in desert plants reduces with reduced photosynthesis and water-use efficiency. The original formation of the dust causing these issues is a direct result of human disturbance, desertification, and change in land management practices.

A=control plant with no dust, growing downslope and upwind of dust

B=heavily dusted plant, growing downwind, adjacent to dust source

Future Prospects

            The future prospects for the Mojave Desert depend on the human population’s dedication to its preservation. There is no doubt that damage has been done to the plant and animal species in the desert, but there is definitely hope for the future. A very positive thing about the future of the Mojave Desert is that it actually recovers faster than most people assumed. However, the recovery time is still lengthy and there is, in fact, some permanent damage that will never recover. Unfortunately, even if we solve all of the problems and eliminate human disturbance, it is unlikely that the Mojave Desert will be fully capable of returning to its original state. If nothing changes and we continue disturbing the Mojave Desert, desert shrubs might continue the trend of decreased photosynthesis and productivity, which will lead to the continuation of temperature increase. We have taken one step in the right direction by eliminating livestock grazing for both economic and conservation purposes, which has helped in the preservation of the land. The USGS is conducting a project in which they use satellite data to determine what recreational activities should be allowed and where they should be allowed to occur. Remote sensing produces satellite imagery that will help the research team figure out what is likely to happen to the desert in the future as well as how susceptible it is to disturbances and how well it will be able to recover.

Improving Human Impacts

             Human impacts and disturbances on the Mojave Desert in California specifically have not been extreme. In fact, the California portion is overall pretty “ecologically intact,” with only a few areas that have been degraded. While this portion of the desert is not in a severe, critical state, its relationship with the human population could be improved. One thing that can be done to improve this relationship is better educating people about the desert so that it is not neglected or ignored. Also, when new information and studies are published, such as the results to the USGS study, it will help greatly if the Mojave Desert land managers follow what they say. When the USGS researchers determine which recreational activities won’t damage the land or the ecosystem, the landowners should strictly enforce that policy. Livestock grazing should continue to be controlled on public land as well. Human disturbances, such as vehicle usage, need to be reduced in order to preserve desert shrubs. This will decrease damage to the shrubs and soil and increase plant production in sites previously disturbed. If windblown dust decreases, desert shrubs will be able to photosynthesize and produce and normal rates, which is crucial to the climate and the ecosystem overall. The Bureau of Land Management, the National Park Service, and the U.S. military should be responsible for not only correcting the destructive ways that they interact with the Mojave Desert, but also for preserving its future.

References

Feller, Walter. "Mojave Desert Map." Mojave Desert. Web. 28 Nov. 2011. <http://digital-desert.com/regions/>.

"DFG - WAP - Introduction to Regions." California Department of Fish and Game. Web. 28 Nov. 2011. <http://www.dfg.ca.gov/wildlife/WAP/statewide-overview.html>.

"The Mojave Desert - DesertUSA." Desert Biomes by DesertUSA. Digital West Media, Inc. Web. 28 Nov. 2011. <http://www.desertusa.com/du_mojave.html>.

Hornung, Armin. "Joshua Tree Park Complete 360° Panorama." Www.ArminHornung.de - Die Homepage Von Armin Hornung: Home. Web. 28 Nov. 2011. <http://www.arminhornung.de/gallery3/index.php/roadtrip07/joshuatree/joshua_tree_360_panorama>.

Michaelson, Joel. "Mojave Desert Region." UC Santa Barbara Geography. Web. 28 Nov. 2011. <http://www.geog.ucsb.edu/~joel/g148_f09/readings/mojave/mojave_desert.html>

Rundel, Philip W., and Arthur C. Gibson. Ecological Communities and Processes in a Mojave Desert Ecosystem. Cambridge: Cambridge UP, 1996. Print.

Sharifi, Rasoul, Arthur Gibson, and Philip Rundel. "Surface Dust Impacts on Gas Exchange in Mojave Desert Shrubs." Journal of Applied Ecology (1997). Print.

Schmidt, Laurie. "Human Impact on the Mojave (DAAC Study) : Feature Articles." NASA Earth Observatory : Home. Web. 28 Nov. 2011. <http://earthobservatory.nasa.gov/Features/Mojave/>.

Thrapp, Dan. "The Nature Conservancy's Mojave Desert Ecoregional Assessment 2010." Scribd. Web. 28 Nov. 2011. <http://www.scribd.com/doc/38896269/The-Nature-Conservancy-s-Mojave-Desert-Ecoregional-Assessment-2010>.