Desertification

Desertification is the degradation of formerly productive land through the expansions of the desert landscape. It is not a simple process and can involve multiple causes and occurs at different rates. Desertification is concerned with desert margins where the landscape changes gradually from a dry, arid climate to a more humid environment. This ‘transition zone’ typically has a fragile and delicately balanced ecosystem. Studies have led scientists to believe that the Sahel region in Africa moved close to 100km southwards between 1950 and 1975 leading to the landscape we see today.

Poor land management is the main factor that contributes to desertification. Increasing populations and larger livestock herds place greater pressure on the desert margins. Local ecosystems become disrupted and can increase the rates of erosion of the land. Nomadic tribes which traverse the landscapes are often trying to escape the desert but unintentionally are taking the desert with them. A greater population leads to a greater need to feed the people. Increased ploughing of the earth for crops further disturbs the landscape. Key words from these ideas are overgrazing, overcultivation, deforestation and sustainability. These are terms which as essential for students to both know and be able to apply to geographical concepts.

Desertification may not be able to be prevented completely but steps to mitigate the human effects can certainly be employed. Better land management is the obvious option. A greater understanding of how planting crops and sufficient irrigation can lead to the stabilisation of soils can ensure that conditions improve. As I suggested it is difficult to reverse losses that have already occurred in terms desert encroachment, however, the Sahel region has proven to buck the trend. An article produced through the BBC website identified regions of the Sahel that have begun retreat (note the article was published in 2002 and subsequently the situation may have changed further). The article highlights both natural and anthropogenic reasons for this.

A UN-sponsored study relating to desertification, known as the Millennium Ecosystem Assessment, was published in 2005 and is well worth a quick scan to get an overall perspective on desertification but also includes some deeper thought into the concept.

Throughout my time that I spent researching this topic the Sahel was clearly favoured as a case study and therefore with the amount of information available it would be a bit silly not to use it as such. It would be useful for student to develop their knowledge around a case study which can be used later in assessments and exams. Other areas can also be used. I came across the below during my research. Asking the question at the beginning of the lesson and then at the end would be a good method to discover whether student has understood the lesson being taught.

The boundary between Chaco Canyon National Monument and the Navajo reservation. On one side, long-term rest from livestock grazing. On the other, livestock grazing with relatively few animals for long periods. Can you tell which is which? Why do you think it looks this way?