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Desertification

Photo taken in Burkina Faso during the dry season shows free-roaming cattle, evergreen trees, and millet residues. Cattle graze on seedlings, reducing shrub and tree cover. In turn there is less fodder during the dry season, and more runoff and erosion when it rains. desertification  


Prepared by Kate Hopfner
(1998 class)

CONTENTS

Agroecosystems Home Page

Overview

Desertification is a serious problem in the Sahel Region of Africa. However, pinpointing the precise cause of desertification is impossible at this time. The cause of desertification was once thought to be simply lack of rainfall, however extensive research has shown it may be much more complex (* DESERTIFICATION AND CLIMATE CHANGE). As the phenomenon of desertification was further studied, more theories as to its cause emerged, many claiming unsuitable agricultural practices in the affected areas as the cause. This agricultural mismanagement usually centered around three separate factors as the cause of desertification whether alone or combined *(PRECIOUS EARTH) These are:

  1. overgrazing by livestock
  2. slashing and burning of forests to clear land for agriculture
  3. separation of perennials from annual crops.

The intercropping of perennials with annual food crops reduces erosion, and shelters annuals from extremes of climate. The removal of perennials leaves annual crops vulnerable.

More recent literature, however. suggests that desertification is not the result of local agricultural mismanagement, but is a natural phenomenon (Mearns, 1997). Some global processes have also been connected to desertification in the Sahel region and elsewhere, including climate change and changes in oceanic circulation. (*DESERTIFICATION AND CLIMATE CHANGE). Regardless of the precise cause of desertification, it is obvious that the effects are very detrimental to local populations of both humans and wildlife.

The effects of desertification can be widely seen in the Sahel. Desertification also has global significance. On a regional scale, desertification threatens local residents by land degradation, reducing the productivity of the land (*DESERTIFICATION - A THREAT TO THE SAHEL). Land degradation occurs by way of erosion and salinization (*IMAGES OF THE CHANGING SAHEL). This causes strain on residents as poor harvests cause hunger, and residents are often forced to move on to new land. The new land often has to be "created" by the destruction of preexisting vegetation, increasing the area of land which is of poor quality. Regionally and globally, desertification can cause extinctions of indigenous plant and animal species (*IMAGES OF THE CHANGING SAHEL). The links between desertification and climate change have also been extensively researched; climate change can be seen in some cases as a cause of desertification and in other cases, an effect of desertification (Williams et al., 1996).

Solutions to desertification in the Sahel region are neither simple nor quickly implemented. This is apparent when one recognizes that the actual cause of desertification is not clear. Regardless, local farming practices can accentuate desertification in the Sahel (*DESERTIFICATION - A THREAT TO THE SAHEL). Unfortunately, to change local farming practices is not a simple matter because there is a tangled web of historical, economic and social factors contributing to desertification in the Sahel (Dregne, 1995). Many countries affected by desertification are developing countries and are the countries which can least afford to implement solutions, especially large-scale ones. Small-scale, local solutions are necessary to change local farming practices. NGOs therefore play a key role, and one we need to support as regional improvements would affect the entire world for the better.

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Key Facts and Figures on Desertification

DESERTIFICATION: Land area affected globally
From: *PRECIOUS EARTH - CHAPTER 1.2.
(See Key Facts and Figures for global land area in agriculture).

Land Type Moderate Desertification
(million ha) 		Severe Desertification
(million ha)
Rangelands 3,100 1,300
Rainfed Cropland 335 170
Irrigated Land 40 13

Other Key Facts and Figures About Desertification:

  • Nine-hundred million people in about 100 countries are at risk from desertification (CIDA, 1997).
  • The countries most affected by desertification are often, economically, the least equipped to solve the problems associated with it (CIDA, 1997).
  • Desertification is occurring in 70% of all drylands, and affects 25% of the total land area of the globe (*BASIC FACTS ON DESERTIFICATION).
  • Desertification has degraded 73% of the world's rangeland (*BASIC FACTS ON DESERTIFICATION).

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Important Terms

Annual Crops
Crops which grow from a seed to maturity, then die within one year.
Desertification
"degradation of land resources in arid, semiarid and dry sub-humid areas resulting from various factors including climatic variations and human activities" (as defined at the United Nations Conference on Environment and Development, 1992)
Erosion
The process by which land is worn away by action of water, wind waves and other forces.
Land Degradation
Loss of soil, water and biodiversity on land.
(*IMAGES OF THE CHANGING SAHEL)
NGOs
Non-governmental organizations (examples range from well-known global organizations like Greenpeace and Red Cross, to local community organizations)
Perennials
A plant which has a life cycle which lasts more than two years.
Sahel Region
Area just south of the Sahara Desert in northwestern Africa which serves as a transition zone between the desert and wetter lands to the south
(*BRIGHT EDGES OF THE EARTH)
Salinization
This refers to accumulation of salts in arid region soils to the point that crop growth is significantly impaired. It is commonly associated with irrigation of arid region soils - salts tend to accumulate because evaporation removes water, leaving the salts behind. If the drainage system is not designed properly or if there is not a season of excess precipitation, or annual floods to wash the salts away away, soils become progressively more salty

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Useful Literature

  • Canadian International Development Agency. 1997. Desertification: Meeting the Challange. Ministry of Public Works and Government Services Canada. Hull, Canada.

  • Ludwig, J. , D. Tongway, D. Freudenberger, J. Noble amd K. Hodgkinson. 1997. Landscape Ecology. Function and Management. CSIRO Australia. Dal Lib. QH 541.5 R3 L35.
    This book develops a landscape approach to managing rangelands, based on principles of landscape ecology, and experience derived from Australian rangelands.

  • Mearns, R. 1997. Livestock and environment: potential for complementarity. World Animal Review : 88: 2-14.

  • Williams, M. and R. C. Balling Jr. 1996. Interactions of Desertification and Climate. Arnold Publishing, London.

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Useful Links

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Cited Literature and Links

  • BASIC FACTS ON DESERTIFICATION
    (http://rolac.unep.mx/deselac/esp/) United Nations Environment Program, Spons. (Viewed 6 Feb. 2001) Note: Spanish Site
  • BRIGHT EDGES OF THE WORLD
    (http://drylands.nasm.edu:1995) United Nations Environment Program and Smithsonian Institution, Spons. (Viewed 6 Feb. 2001)
  • CIDA. 1997. Desertification: Meeting the Challange. Ministry of Public Works and Government Services Canada. Hull, Canada. Dal. Lib. GB 612 D47 1997
  • DESERTIFICATION - A THREAT TO THE SAHEL
    (http://www.eden-foundation.org/project/desertif.html) Eden Foundation, Spons. (2000, February 3; Viewed 6 Feb. 2001)
  • DESERTIFICATION AND CLIMATE CHANGE ( Tiempo Issue 9)
    (http://www.cru.uea.ac.uk/tiempo/floor0/archive/issue09/t9art1.html) Mick Kelly and Mike Hulme, Auth. (1993, August; Viewed 6 Feb. 2001)
  • Dregne, H.E. 1995. Desertification control: a framework for action. Environmental Monitor Assessment 37: 111-121.
  • Mearns, R. 1997. Livestock and environment: potential for complementarity. World Animal Review 88: 2-14.
  • PRECIOUS EARTH - CHAPTER 1.2
    (http://www.giub.unibe.ch/cde/isco/isco12.html) Department of Geography, University of Berne, Switzerland, Spons. (1995, December; Viewed 6 Feb. 2001)
  • Williams, M. and R. C. Balling Jr. 1996. Interactions of Desertification and Climate. Arnold Publishings. London. Dal. Lib. GB612 W55 1996

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