|Environmental Education in the Schools (Peace Corps, 1993)|
|Activities, activities and more activities|
What happens when human population growth exceeds the carrying capacity of an environment? What, if any, are limiting factors to continued human population growth? These questions are addressed in this case study of the Sahel famine. The disastrous drought that struck the Sahel region of Africa from 1968 to 1973 and the famine that followed focused worldwide attention on the problem of desertification. Desertification-a destruction of the biological potential or carrying capacity of the land-can ultimately lead to the formation of desert-like conditions as soil fertility declines.
The story of the Sahel famine illustrates how the interaction of social and environmental factors can lead to desertification. The fragile semi-desert environment of the Sahel region is being taxed to its limits by the rapidly expanding human population. Media images of starving children in Ethiopia have brought home the harsh realities of people barely coexisting with a parched land. Human population growth continues to exceed food production, and soil fertility continues to decline.
On a global level, over 20 percent of the Earth's land surface and 80 million people are under direct threat of desertification. Countries of the world are working together to study the problem and devise strategies for restoring the productivity of desertified lands.
1. Before distributing the case study, review any vocabulary words that may be new to your students. Point out the Sahel region on a world map. Note: These countries are outlined on the map of Africa on page 251.
2. When students have had the opportunity to read the Sahel case study, divide the class into discussion groups. Give each group a large sheet of paper and ask them to work out a diagram depicting the sequence of events leading to the famine. (This diagram is depicted on page 252.)
3. Ask each group to present their diagram to the class and discuss how social and biological events are interrelated as the cause of desertification in the Sahel region. Some additional discussion might focus on the following questions:* What are some of the limiting factors of the Sahel region for
* How did the well-meaning intervention of France contribute to the problems of overgrazing and overcultivation? (colonization of nomads and introduction of cash crops)
* Has the carrying capacity of the land been exceeded? Explain. (The pressures of increased human population and increased cattle on the land have reduced the ability of the land to support life.)
Pass out copies of page 252 and review the interrelated chain of events leading to desertification.
4. Ask students to generate some strategies for solving the problems of desertification. The key to combating the problem is proper land use. Following are some general recommendations for controlling the problems:* Develop grazing practices that allow the vegetation to recuperate.
* Limit overgrazing and trampling around watering areas. If a rest period is needed for vegetation, any well in the area should be closed.
* Limit the number of cattle on the range.
* Plant trees and shrubs in reforestation efforts.
* Regulate cutting of forests for fuelwood.
* Restore fallow periods for cultivated lands.
* Initiate population control measures.
Limiting the number of cattle on the range is a key to solving the problem. However, this solution involves breaking a long-standing tradition in the Sahel where cattle are viewed as insurance against hard times. The need for education is recognized as an important part of the solution. Unfortunately, nomads of the Sahel are understandably suspicious of outside intervention. Some progress is being made, however.
In southern Niger, CARE workers are planting trees as windbreaks and increasing numbers of farmers are planting trees as a crop. Research is also being conducted to increase agricultural yields under semi-arid conditions.
5. Are We Creating Deserts?
Refer to the map here and help students identify global areas threatened by desertification. One third of the Earth's surface is arid or semi-arid. We have currently desertified an area approximately the size of China. The Global 2000 Report indicates that present global losses to desertification are estimated at approximately six million hectares a year, or an area roughly the size of Maine.
Source: Intercom #83, Shaping the Environment David C. King and Cathryn J. Long Center for Global Perspectives.
"The nation that destroys its soil destroys
-Franklin D. Roosevelt
Conduct a compaction demonstration to help students understand how compaction of the soil reduces its permeability or capacity to absorb water. Cut the top and bottom out of two equal-size cans. Fill a half-gallon container with water. Then go out onto the school grounds and place one can a half inch down in the soil of a well traveled path or athletic field devoid of vegetation. Place the other can in the same type of soil in an area that has not been trampled. Pour an equal amount of water in each can and measure the amount of time it takes for the water to be completely absorbed. Ask students to account for the different absorption rates and relate this to problems of overgrazing. Bring out the fact that rain falling on compacted soils will run off and cause soil erosion. Plant roots are unable to penetrate the compacted soils and hold them in place.
Have students investigate the problem of desertification in the United States. Compared to the scale of human suffering and environmental destruction in the Sahel, our land use problems from overgrazing, deforestation and soil erosion may look minor; but destruction of rangelands and loss of topsoil present problems worthy of serious consideration. Some Bureau of Land Management employees have referred to rangelands under their jurisdiction as "10- 80 lands." This refers to the fact that the range has so long been overgrazed that "a cow needs a mouth 10 feet wide and has to run 80 miles an hour just to get enough to eat." According to the United States Department of Agriculture, over half of the 414 million acres of rangeland in the continental United States are in "poor" or "very poor" condition. They report that only 15 percent of the rangeland remains in good condition.
In 1978 the Public Rangelands Improvement Act was passed that authorized a maintenance, management, and improvement program. Have students compose a class letter to the Bureau of Land Management to find out more about this act and how it is being carried out today.
Bureau of Land Management
U.S. Department of the Interior
Washington, DC 20240