Desertification as land cover change: VCE Geography
“The processes and human activities causing desertification as a form of land cover change, and the impacts of and responses to desertification”
Desertification is the degradation of dryland into desert-like conditions, driven by a combination of climate stress (drought) and human pressures such as overgrazing, overcultivation, deforestation and poor irrigation. It strips vegetation cover, exposes soil to erosion and reduces productivity. Responses include sustainable land management, reforestation barriers and international action under the United Nations.
What this dot point is asking
VCAA wants you to explain desertification as a land cover change, distinguish the natural and human processes that cause it, evaluate its impacts on people and the environment, and assess responses. Use a precisely located case study with data.
What desertification is
Desertification is land degradation in arid, semi-arid and dry sub-humid areas, where vegetation cover is lost and fertile land takes on the characteristics of desert. It is not the natural expansion of existing deserts but the creation of desert-like conditions on once-productive land, usually at the margins of drylands where rainfall is low and variable.
Causes: natural and human processes
- Drought and climate variability reduce rainfall and stress vegetation, the natural trigger.
- Overgrazing by too many livestock strips the protective plant cover, exposing bare soil.
- Overcultivation exhausts soil nutrients and structure when land is farmed too intensively.
- Deforestation and fuelwood collection remove trees that anchor soil and retain moisture.
- Poor irrigation can cause salinisation, where salts accumulate in the soil and poison plants.
- Population pressure intensifies all of these as more people demand food, fuel and grazing from fragile land.
Case study: the African Sahel
The Sahel is a semi-arid belt stretching across Africa just south of the Sahara, through countries including Mali, Niger, Chad and Sudan. It suffers from highly variable rainfall and recurrent drought, most severely in the 1970s and 1980s, when crops failed and famine killed many people. A rapidly growing population has expanded cropping and herding onto marginal land, while fuelwood collection has stripped tree cover. Together, drought and human pressure have degraded large areas of soil.
The United Nations estimates that desertification and drought affect the livelihoods of well over one billion people worldwide, and that drylands cover around 40 percent of the Earth's land surface, making this one of the most widespread forms of land cover change.
Impacts on the environment
Desertification removes vegetation, so soil is exposed to wind and water erosion and can be blown or washed away. Soil fertility, structure and moisture decline, making recovery slow or impossible. Biodiversity falls as habitat is lost. Dust storms increase, and loss of vegetation reduces the land's ability to store carbon, adding to climate change.
Impacts on people
Degraded land produces less food, so crop yields and livestock numbers fall, threatening food security and incomes for some of the world's poorest people. This can drive hunger and, in severe cases, famine. Loss of livelihoods pushes people to migrate to cities or across borders, and competition for shrinking productive land can fuel conflict. Communities lose the natural resource base on which their culture and survival depend.
Question: Distinguish between a cause and an impact of desertification.
Strong answer: A cause of desertification is overgrazing, where too many livestock strip the vegetation cover from semi-arid land, leaving soil bare and exposed. An impact of desertification is reduced food security, because once the soil erodes and fertility falls, crops and pasture produce far less, so communities such as those in the Sahel face hunger and may be forced to migrate. The cause is the human activity that triggers the change; the impact is the consequence that follows once the land has degraded.
Responses to desertification
- Sustainable land management, including rotational grazing, terracing and leaving land fallow, lets soil recover.
- The Great Green Wall initiative aims to restore a band of vegetation across the southern edge of the Sahara to hold back degradation.
- Reforestation and water harvesting, such as planting trees and building small stone barriers (zai pits and demi-lunes) in Niger and Burkina Faso, trap water and rebuild soil.
- The United Nations Convention to Combat Desertification (UNCCD) coordinates international funding and policy.
A common error is describing desertification as deserts simply growing larger and spreading across the land. Examiners want you to explain it as the degradation of productive dryland into desert-like conditions, usually at dryland margins, caused by the interaction of drought with human pressures such as overgrazing and overcultivation. Naming the human causes is what separates a strong answer from a weak one.
Exam-style questions
Questions in the style of VCAA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
Practice7 marksExplain two interconnected human activities causing desertification at a selected location you have studied this year.Show worked answer →
For 7 marks, name a precise location, then explain two human activities and show explicitly how they reinforce one another, not just list them. A useful split is roughly 3 marks per activity plus 1 mark for the interconnection.
Using the Sahel: "In the African Sahel, the two leading human causes are overgrazing and fuelwood collection. A growing population grazes more livestock than the fragile semi-arid pasture can support, stripping the protective plant cover. The same population removes trees and shrubs for cooking fuel, exposing more bare soil."
Interconnection: "These activities are interconnected because removing trees for fuel reduces the shade and root binding that pasture relies on, while heavier grazing prevents the tree seedlings from re-establishing, so the two pressures together accelerate the loss of vegetation cover far faster than either alone."
Markers reward a located example, two genuine human activities and an explicit causal link, not a list of all six textbook causes.
Practice10 marksName the location of your selected example of desertification. a. Outline one environmental impact and one impact on social conditions at this location (4 marks). b. Evaluate the likely effectiveness of one response to the impact on social conditions outlined in part a (6 marks).Show worked answer →
Part a (4 marks): name a precise location, then outline one environmental and one social impact, about 2 marks each. Using the Sahel: "Environmental: loss of vegetation exposes soil to wind erosion and dust storms, lowering soil fertility. Social: falling crop yields and livestock numbers threaten food security, driving hunger and out-migration from rural villages."
Part b (6 marks): name a response to the social impact, then evaluate with strengths and limitations and a judgement. "A response to declining food security is the Great Green Wall and water-harvesting techniques such as zai pits. Strength: restored vegetation and trapped rainfall have rehabilitated degraded land in Niger and Burkina Faso, lifting yields and incomes. Limitation: progress is uneven, funding is inconsistent, and conflict and continued population growth keep pressure on the land, so the response is only partially effective."
Markers reward a located example, distinct environmental and social impacts, a named response, balanced evaluation and a clear judgement.