INDEXABOUT USE-MAIL USESPAÑOL
DESERTIFICATION
By Nasif Nahle, biologist
June 26, 2004


CURRENT DATA:

Arable lands constitute a 13.5% of the continental surface.

Permanent arable lands constitute a 4% of the world’s surface.

One third of the continental surface is bein deprived of the fertile layer of soil.

Since 1490 until now, more than 4 billion hectares of fertile soil have been destroyed by climate variability, harvesting, grazing, industrialization and urban growth.

About 20 billion tons of fertile soils are destroyed each year by fire and winds.

OUR EXPERIENCE:

March 1987-- Intense winds dragged a dense cloud of reddish dust that darkened the diurnal sky forming a band which stretched from the Tropic of Cancer to near the Equator. The spectacle, which dyed the daylight on red, lasted for more than four hours.

Ten years later, on August 1997, during an excursion to the city of Zacatecas, Mexico, I stumbled upon a Pan-American highway blocked by reddish sand dunes! The large healthy farming areas that I have seen 20 years before have become into a far-reaching desert. Sand dunes and rocky soils dominated the scene.

On April 2001, once again, the northern sky was covered by a dense cloud of dust. The reddish hued light wrapped our group for more than six hours. The origin of that reddish dust was the same that I have seen in 1987. The reddish dust had been picked up by the winds from the fields of the state of Zacatecas, Durango and San Luis Potosi. In that occasion, the area of dust dispersal was wider than during the 1987 event. I realized it because I also received reports about the phenomenon coming from Texas, US.

We call the phenomenon "red wind" because it transports reddish dust.

WHAT DOES DESERTIFICATION MEAN?

Desertification refers to the degradation of soil in Arid, semiarid and subhumid lands due to the Climate Variability and human activities.

Among the human activities, we identify farming like the main cause of desertification because farmers persistently grow crops and fairly distribute farm animals on grazing lands through more than 20 years.

There is also a link between acid rain -caused by atmospheric pollution- and desertification because the sulfur-derived acids destroy diverse life forms that supply of biodegradable materials to soils, for example bacteria and earthworms.

Desertification can also occur naturally like the last phase of an ecological succession. However, with the association of Climate Variability and the expansion of the human communities, which as they grow they demand greater quantities of food originating from agriculture and stockbreeding. The arid, semiarid and subhumid lands have been degraded in all continents by a farming overexploitation.

The European countries more affected by land degradation are Armenia, Azerbaijan, Bulgaria, Rumania and Russia.

Africa holds a dramatic and astounding situation because more than three billion hectares of prairies and sub humid forests are above the process of desertification due to unrestrained destruction by fire of vast prairies, agricultural and stockbreeding overexploitation, irregularity of pluvial precipitations -that happen after long periods of drought- and severe erosion of soils by winds. The rate of soils’ degradation has been calculated in more than 100 thousand hectares per year. The deserted areas in Africa reach already a 73% (almost 2/3 of the African continent).

Asia holds 1.7 billion hectares of arid regions. The depths of despair are that the Asian populations are spreading out beyond deserts (it would be as a gravitational field that expands above other gravitational fields).

In China, a fast industrialization has propitiated the destruction of grasslands and humid forests by the development of industrial parks and the increase of rice harvest. The desertification in China has been speeded up by the exploitation of coal from woods as a main supply of energy. Large areas of tropical pluvial forests have been chopped down to obtain coal from trees to use it in a boosting industry.

There are 20.5 million square Kilometers of deserts in Latin America. Atacama Desert is one of the more famous deserts. It locates in Chile and extends from the South border of Peru to the North border of Argentina. It is almost 1000 Km in length and 160 Km wide. Atacama Desert is an old arid region that has volcanic and saline soils; however, the agriculture exploited at its peripheries has propitiated a haste advance of the desertification barely in ten years.

In Mexico, a belt of severe desertification extends from Sonora to San Luis Potosi. The mexican belt of desertification is a wide strip that advances from Chiapas to Baja California -It includes a great portion of the Mexican Central Plateau (Anahuac Plateau), like the states of Sonora, Chihuahua, Durango, Zacatecas, Coahuila, and San Luis Potosi. The excess on agricultural exploitation of rustic lands generated a severe degradation of the soils. Other areas of the Mexican Republic that display serious desertification are Southwest of Veracruz and the states of Chiapas, Guerrero, Oaxaca and Michoacan. At these states, the agricultural overexploitation and the devastation of woodlands have largely contributed to the erosion of soils.

In USA, the erosion by winds and water, the continuous dryness and the intensive rustic activities on till and no-till fields have provoked a conspicuous desertification that has positioned the problematic of the Midwest and Midland’s prairies (Great Plaines) among the more destructive phenomena in the American Union.

Texas shares with the Midwest and the Great Plains a very high level of soil degradation as a result of continuous drought, wind erosion and an unconscious exploitation of soils by rural and industrial activities.

The incontrollable and irreversible advance of desertification in the United States is a very frustrating situation and it is a good example on how do the political affairs influence directly in the devastation of formerly-dynamic environments.

WHY DESERTIFICATION IS SO BAD FOR LIFE ON EARTH? 

Arid, semiarid and grasslands or subhumid ecosystems are the natural habitat of thousands of plant and animal species that are annihilated by the destruction of the Biomes where they live. This has been one of the main sources in the decreasing of biodiversity in our planet.

Semiarid and grasslands or subhumid ecosystems produce almost a 15% of the planet’s Oxygen.

Humus, or fertile layer in arid, semiarid, grasslands and subhumid ecosystems, retains the rainy water through longer periods, impeding the impetuous and vertiginous flow of water. Humus also slows down water evaporation at isohyets.

The desertification is established as the loss of the fertile layer of soils (humus), which is the layer that gives support to wild or cultivated plants, whether. Fertile layer also works as a retainer of water. Thus, desertification affects the economy of the nations maintained by agriculture because desertification weakens to agricultural productivity.

The degradation of soils means a less food production for humans and their livestock. Damage on fertile soils equals to less food and more starvation on our planet. Dfs= St/F (Damage on fertile soils [Dfs] is proportional to Starvation [St] an inversely proportional to Food production [F].)

WHAT CAN WE DO? 

Not too much. The responsibility involves to all us; however, we can do almost nothing to set back the fast advance of deterioration of the fertile layer of soil.

Abandoning all the fertile lands through the next 100 years will regenerate only 1% from the total of soils destroyed until now.

It is urgent that we stop now the global chaotic and impulsive destruction of woodlands. The practice of burning grass lands and shrubs to strip lands for farming and urbanizing must be catalogued like an ominous transgression against humankind.

Each nation has created research commissions to assess the best way to stop the problem of desertification; however, we know little about those commissions’ work because, at fighting against desertification, we humans are in absolute disadvantage. We know how to destroy the Biosphere, but we do not know how to drive it backwards. 

DESERTIFICATION IS AN IRREVERSIBLE PROCESS. TODAY, YOU AND ME ARE AWARE OF THIS PROBLEM. WHAT WE ONLY CAN DO IS TEACHING OTHERS TO DO NOT PERPETRATE OUR PRECEDING MISTAKES AND TO PREVENT, MORE THAN FIXING, THE PROBLEM... ONCE ESTABLISHED IN A SPECIFIC AREA, DESERTIFICATION CANNOT BE REVERSED.

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RESOURCES

Ash, Caroline. Desert Rescue. Science, Vol 291, Issue 5509, 1667 , 2 March 2001.

Brown, James H., et al. Complex Species Interactions and the Dynamics of Ecological Systems: Long-Term Experiments. Science, Vol 293, Issue 5530,
643-650 , 27 July 2001.

Sustainable development of drylands and combating desertification.
http://www.fao.org/documents/show_cdr.asp?url_file=/docrep/V0265E/V0265E00.htm. FAO's Website.

Desertification. USGS's Website: http://pubs.usgs.gov/gip/deserts/desertification/

Frazier, Thomas W. Natural and Bioterrorist/Biocriminal Threats to Food and Agriculture. Annals of the New York Academy of Sciences. 894:1-8 (1999). New York, NY.

Picture: Kenya’s Ewaso Nyiro River Dries.

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Copyright© 2004 by Biology Cabinet Organization
ALL RIGHTS RESERVED.
New Braunfels, TX.
DESERTIFICATION
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This image shows the dried river bed of the River Ewaso Nyiro in this true-colors image. The image was captured by the Advanced Land Imager on NASA’s EO-1 satellite on 27 September 2009.

The cause of the Ewaso Nyiro River drying has been severe drought ravaged to Kenya and surrounding countries for almost a year. Source: NASA Earth Observatory.