3.2.5. Desertification

Desertification is the process which turns productive into non-productive desert as a result of poor land-management. Desertification occurs mainly in semi-arid areas (average annual rainfall less than 600 mm) bordering on deserts. In the Sahel, (the semi-arid area south of the Sahara Desert), for example, the desert moved 100 km southwards between 1950 and 1975.

Desertification is when fertile land becomes desert due to mismanagement and other factors. It usually happens in areas that are on the edge of deserts, where the rainfall is very low. A notable example includes the Sahel region, where the desert has expanded significantly, making once productive land unusable.

Think of desertification like a slow-moving avalanche. At first, the land is rich and healthy, but if people cut down trees and overgraze, it's like loosening the snow. Eventually, the weight of poor practices causes the land to slide into desert, just as snow turns to ice after an avalanche.

• Overgrazing is the major cause of desertification worldwide. Plants of semi-arid areas are adapted to being eaten by sparsely scattered, large, grazing mammals which move in response to the patchy rainfall common to these regions. Early human pastoralists living in semi-arid areas copied this natural system. They moved their small groups of domestic animals in response to food and water availability. Such regular stock movement prevented overgrazing of the fragile plant cover. * Cultivation of marginal lands, i.e., lands on which there is a high risk of crop failure and a very low economic return, for example, some parts of South Africa where maize is grown. * Destruction of vegetation in arid regions, often for fuelwood. * Poor grazing management after accidental burning of semi-arid vegetation. * Incorrect irrigation practices in arid areas can cause salinization, (the buildup of salts in the soil) which can prevent plant growth. When the practices described above coincide with drought, the rate of desertification increases dramatically.

Desertification is caused mainly by human activities, such as overgrazing, which damages the plant cover essential to retain soil and moisture. When people farm on marginal lands or destroy vegetation for fuel, they exacerbate the problems. Poor irrigation can also lead to salinization, making the soil less suitable for growing plants. In dry times, such practices can make desertification much worse.

Imagine a community that relies on a local well for water. If many people continuously take water without letting it refill, eventually, the well runs dry. Similarly, overgrazing or poor farming practices can deplete the land's resources until it can no longer sustain life.

Desertification reduces the ability of land to support life, affecting wild species, domestic animals, agricultural crops, and people. The reduction in plant cover that accompanies desertification leads to accelerated soil erosion by wind and water. South Africa is losing approximately 300-400 million tonnes of topsoil every year. As vegetation cover and soil layer are reduced, rain drop impact and run-off increases. Water is lost off the land instead of soaking into the soil to provide moisture for plants. Even long-lived plants that would normally survive droughts die. A reduction in plant cover also results in a reduction in the quantity of humus and plant nutrients in the soil, and plant production drops further. As protective plant cover disappears, floods become more frequent and more severe. Desertification is self-reinforcing, i.e., once the process has started, and conditions are set for continual deterioration.

Desertification severely impacts the land's ability to support living beings. As plants die off due to poor management, soils erode more easily, and water cannot be absorbed, leading to further issues like increased flooding. This downward spiral can result in critical situations where both agriculture and natural ecosystems collapse, making recovery increasingly difficult.

Think of a well-tended garden. If you stop watering and caring for it, weeds take over, making it hard for plants to grow. Similarly, when land is mismanaged, it can quickly degrade, as once-thriving areas become too dry to support life, highlighting how essential responsible management is.

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