Tuesday, November 27, 2012



The Sahara Desert is the world's third largest desert after Antarctica and Arctic, and the largest hot desert. The desert spreads across the northern part of the continent of Africa with an area of around 1.8 million square miles and more than 9,000,000 square km. "It covers nearly eleven countries and in terms of area, Sahara desert can be considered equivalent to the continent of America. The desert divides the continent of Africa into two parts - North and Sub-Saharan Africa."


In terms of topography, the Sahara desert has a wide variety of surface types. There are stone plateaus, sand dunes, gravel plains, salt flats and dry valleys. The area harbors many deeply dissected mountain ranges that at times form their own smaller ecosystems. Underground aquifers that have risen above the surface level form magical oases.

The ecological region of the desert is mostly hyper arid that receives extremely low rainfall (with less than 25 mm of mean annual rainfall) at sporadic intervals. The major problem with the Sahara desert is that it lies in climatic divide. The winter rain that falls on North Africa does not reach south enough to bring rain to the central Sahara. On the other hand, the rain from at the Intercontinental Convergence Zone moves up south, but stops way before it can reach the central part of the Sahara. The northern and southern parts of the desert receive comparatively greater rainfall, and therefore have more vegetation cover.


The Sahara Desert comes under one of the hottest regions in the world. The average temperature of the desert is in around 86 degree Fahrenheit. In summers, the temperatures can rise over 110 Fahrenheit, whereas in winters it can fall below freezing. Since there is extremely limited cloud cover, the temperatures vary daily to a great extent.

Due to harsh climatic conditions like extreme heat and low rainfall, the region fosters a limited variety of species. Living organisms that do survive have adapted to notable extents. The highest concentrations of plants exist along the northern and southern margins of the desert and near the oases and drainages. Similarly, the vegetation in the western part of the desert is more than the eastern part since the western part receives relatively more rainfall.

For obvious reasons, the Saharan flora is extremely poor with only 500 or so species. This number is very low in relation to the geographic area of the region.

On the other hand the fauna of the Sahara Desert is relatively richer than what it is perceived to be as. There are almost 70 different species of mammal with around 20 being classified to be large mammals. The Saharan Desert also fosters around 100 species of reptiles and 90 species of resident birds. There are also numerous arthropods like ants.


Historical State of the Ecosystem

"The history of the desert dates back to 3 million years ago." It has been researched that only a few thousand years ago the Sahara Desert was a region with significantly large amount of precipitation and fauna. It is believed that climatic changes over the past 5000 years, and intense hunting by man over the last millennium has eradicated the existing faunas. "According to archeologists, the Sahara was much more densely populated thousands of years ago when the desert's climate was not as harsh as it is today Earlier, the desert used to be a fertile area, in which elephants, giraffes and other animals grazed. Slowly it started becoming drier and the fertile landscape gave way to infertile region, as we see today. Fossils, rock art, stone artifacts, bone harpoons, shells and many other items have been found in areas which today are considered too hot and dry to inhabit. This suggests that these areas were quite habitable thousands of years ago, but that the climate of the Sahara has since changed drastically due to natural means. The artifacts found were located near remains of giraffe, elephant, buffalo, antelopes, rhinoceros, and warthog, as well as the remains of fish, crocodiles, hippopotamuses and other aquatic animals which suggests that thousands of years ago water was quite abundant in the Sahara." (http://library.thinkquest.org/16645/the_land/saha_tp.shtml)

Although no particular conclusion has been reached as to what was the exact historical state of the Sahara Desert, it is widely believed that the desert has undergone some enormous variation between wet and dry over the last hundred thousand years. During the last ice age, the Sahara Desert was close to what it is today. However, by the end of the last ice age, the area saw a rise in precipitation. Since then, climatic changes have led the region to be a desert like it once was.


What the Sahara Desert looked like thousands of years ago.


What the Sahara Desert looks like.

Current Human Impacts on the Ecosystem

Although the Sahara desert has reached its current status of a desert due to natural reasons, mankind has made (and continues to make) its share of impact on the region as well. Most part of the Sahara Desert is a relatively untouched habitat with sands and rocks and small patches of vegetation. The major degradation that does occur, takes place in areas where there is presence of water. Over here, the ecosystems are largely affected by human activities.

The local pressure on the natural resources of areas with bodies of water (like oases) is a major threat to the surviving ecosystems of the Sahara desert. The pressure is put in terms of:
·        Hunting for food
·        Deforestation for fuel and building
·        Overgrazing by sheep and cattle resulting in plant destruction destroy.
·        Consumption of water for domestic purposes
·        Infrastructure development (building of roads and houses)
·        Desert Driving over vegetation (for both domestic and recreation purposes)
·        Solar power farms.
·        Rally car races.
       ·        Desert farms. 

Future Prospects of the Ecosystem based on Current Human Impacts

In essence, the Sahara Desert is not a well-protected ecosystem when compared to its counterparts in America and Europe. "Yet, this may be due to the low population and impracticality of defining borders over this vast area. Fewer than two million inhabitants reside throughout the entire Sahara Desert. The majority are nomads, predominantly the Tuareg, Tibbu, and Moors. They survive by nomadic pastoralism, hunting, and trading. Most of these people are found in the desert margins and they do not often spend much time in the central hyper-arid portion."  

As of today, there is only one tiny protected natural reserve area in the Sahara Desert – The Zellaf Nature Reserve in Libya – which stretches only 1000 square kilometers. The development projects that have started in the deserts of Algeria and Tunisia using irrigated water pumped from underground aquifers have led to salinization and soil degradation. This has further destroyed the existing ecosystems. There is an urgent need to create more protected areas as not only will it benefit the wildlife and the habitat but also improve the lives of the local nomadic people by increasing ecotourism and boosting domestic economy.

There has been great pressure on the few remaining populations of large mammals that have managed adapt to the harsh desert conditions. Populations of almost all organisms have been on a sharp decline. For example, the addax is now critically threatened with extinction due to over-hunting. Most of the other desert-adapted antelopes are also in danger of extinction.

Proposals to improve the Human Impact on the Ecosystem

If things continue to be the way they have been for the past few decades, the natural ecosystems in the Sahara Desert will be completely destroyed. There is an urgent need for the establishment of natural reserves by strong foundations like World Wide Fund (WWF).

It is possible that the Sahara Desert be utilized in a manner that does not impact the ecosystems. There can be installation of Solar Projects to accommodate the energy needs of the area’s residents. It is believed that if only 0.3% of the Saharan Desert was used for a concentrating solar plant, it would produce enough energy to sustain Europe.

Water treatment plants should be set up that process sea water (instead of oases) water for drinking and domestic purposes.  This will greatly help to save the small ecosystems surrounding oases to be affected negatively. These measures can only be reached with the help of strong foundations and developed economies since the current state of affairs in Africa is far away from allowing people to live a reasonable standard of living, let alone a drive to support environmental conservation.

The figure above shows Vegetation cover and  precipitation patterns of Africa. Patterns of precipitation (expressed as annual means, in units of mm/y) are tightly correlated with patterns of vegetation cover. Northern Africa is dominated by the Sahara, the largest hot desert on the planet today. The transition between the Sahara and the savannas to the south occurs in the Sahel zone (outlined in black). A close up of Sahara is in the image below which shows vegetation cover to the south of Sahara:



Sahara desert is slowly expanding, consuming the more productive ecosystems to the south. This process of desertification —the loss of perennial vegetation and topsoil and the associated decline in
biological productivity—is often cited as one of the main ecological threats 

Reference list
             1. "Northern Africa." Wildlife Conservation, Endangered Species Conservation. N.p., n.d. Web. <http://worldwildlife.org/ecoregions/pa1327>
             2. "Sahara Desert Was Once Lush and Populated." LiveScience.com. N.p., n.d. Web. <http://www.livescience.com/4180-sahara-desert-lush-populated.html>

1.           3. "Ecosystem." - National Geographic Education. N.p., n.d. Web. <http://education.nationalgeographic.com/education/encyclopedia/ecosystem/?ar_a=1>
   4. "Sahara Desert Facts." - Interesting And Fun Facts About Sahara Desert. N.p., n.d. Web. <http://lifestyle.iloveindia.com/lounge/sahara-desert-facts-3619.html>
5. The Sahara Desert Apr 08, 2010." The Sahara Desert. N.p., n.d. Web. <http://www.thunderbolts.info/tpod/2010/arch10/100408sahara.htm>
 6. "The Sahara Desert." : Wildlife, Plants, People and Cultures, Interesting Facts. N.p., n.d. Web. <http://www.desertusa.com/du_sahara_life.html>
7. "The Living Africa: The Land." ThinkQuest. Oracle Foundation, n.d. Web. <http://library.thinkquest.org/16645/the_land/saha_tp.shtml>
8. "World’s Largest Solar Project Planned for Saharan Desert | Inhabitat - Sustainable Design Innovation, Eco Architecture, Green Building." In habitat Sustainable Design Innovation Eco Architecture Green Building Worlds Largest Solar Project Planned for Saharan Desert Comments. N.p., n.d. Web.  
            9. "Sahara Desert." Sahara Desert. N.p., n.d. Web.
            10. "Expansion and Contraction of the Sahara Desert from 1980 to 1990"
                    Compton J. Tucker, Harold E. Dregne, Wilbur W. Newcomb       
            11. "Regime Shifts in the Sahara and Sahel: Interactions between Ecological and Climatic Systems in  Northern Africa"
                    Jonathan A. Foley, Michael T. Coe, Marten Scheffer                


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