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Team:Imperial College London/Project/Background
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text[0] = "Hover over the map to read about the impact of desertification in different areas."; | text[0] = "Hover over the map to read about the impact of desertification in different areas."; | ||
| - | text[1] = "Africa is the region most affected by desertification. Two thirds of the continent is covered by drylands which is used extensively for agricultural production. Over-cultivation has led to large scale degradation, exacerbated by frequent drought, leading to extreme food scarcity for over 650 million people who are dependent on the affected land. If the degradation trend continues, it is estimated that two thirds of Africa’s arable may be lost by 2025 (FAO 2009). In an effort to combat desertification, 11 countries along the southern border of the Sahara are involved in the Great Green Wall project. With the help of international aid, the objective is to cover 8,000 km of dryland with vegetation as a protective barrier from erosive forces. However the operation is extremely time consuming and will take a long time before it is established."; | + | text[1] = "Africa is the region most affected by desertification. Two thirds of the continent is covered by drylands which is used extensively for agricultural production. Over-cultivation has led to large scale degradation, exacerbated by frequent drought, leading to extreme food scarcity for over 650 million people who are dependent on the affected land. If the degradation trend continues, it is estimated that two thirds of Africa’s arable land may be lost by 2025 (FAO 2009). In an effort to combat desertification, 11 countries along the southern border of the Sahara are involved in the Great Green Wall project. With the help of international aid, the objective is to cover 8,000 km of dryland with vegetation as a protective barrier from erosive forces. However the operation is extremely time consuming and will take a long time before it is established."; |
text[2] = "North America experienced one of the most extreme effects of desertification during the 1930s. The famous dust bowls of the Great Plains were brought on by over-cultivation of land and severe drought, causing degraded soil to be swept up by strong winds. Today, about three quarters of North America’s drylands are affected by desertification. Counter-measures include synthetic materials to protect dryland, trenches to collect water, and windbreak structures."; | text[2] = "North America experienced one of the most extreme effects of desertification during the 1930s. The famous dust bowls of the Great Plains were brought on by over-cultivation of land and severe drought, causing degraded soil to be swept up by strong winds. Today, about three quarters of North America’s drylands are affected by desertification. Counter-measures include synthetic materials to protect dryland, trenches to collect water, and windbreak structures."; | ||
text[3] = "China is one of the largest dryland areas in the world, nearly a quarter of which is at risk of desertification. The problem has been fed by large-scale industrialisation with the over-use of land and water resources, as well as prolonged drought. Since 1978 the Great Green Wall project has been underway in the Kubuqi desert to protect cities from wind erosion carrying dust. The trees (Xinjiang poplars and willow species) are planted as saplings protected with wooden frames so they can take root before being blown away. These plants form fibrous roots that help hold down the sand. Although this project has slowed the desertification process in China, it remains an imminent problem."; | text[3] = "China is one of the largest dryland areas in the world, nearly a quarter of which is at risk of desertification. The problem has been fed by large-scale industrialisation with the over-use of land and water resources, as well as prolonged drought. Since 1978 the Great Green Wall project has been underway in the Kubuqi desert to protect cities from wind erosion carrying dust. The trees (Xinjiang poplars and willow species) are planted as saplings protected with wooden frames so they can take root before being blown away. These plants form fibrous roots that help hold down the sand. Although this project has slowed the desertification process in China, it remains an imminent problem."; | ||
Revision as of 19:18, 19 September 2011
Desertification
Desertification is the degradation of drylands which include arid, semi-arid and sub-humid areas. Drylands make up roughly 40 percent of the Earth’s land and are home to some two billion people, most of which live in developing countries. Dryland soil sustains a fragile ecosystem adapted to infrequent precipitation and dramatic temperature changes. Over-exploitation of dryland for cultivation and feedstock purposes renders the soil unproductive, forcing migration of communities in search of fertile land, leaving the unproductive land bare and vulnerable to erosive forces. A lack of food supply in many developing countries forces constant cultivation of land for short-term gain as well as deforestation to provide arable land.
Case studies
Downstream Effects
Soil affects the climate and biodiversity and leads to often irreversible desertification (see figure above). Roots increase the stability of soil and prevent erosion (Gyssels & Poesen, 2003). In addition, trees provide cover and protect nearby fauna and flora. In areas prone to soil erosion, this is especially important as rainfall tends to be rare but when it does occur, it is often very intense and easily leads to topsoil being washed away. Roots are also important carbon sinks. Increasing root biomass is therefore very likely to improve the carbon budget of the plants we are seeding (Dr Alexandru Milcu, oral communication).
Image taken from the Millenium Ecosystems Assessment - Desertification synthesis [1].
References:
[1] Millenium Ecosystem Assessment (2005) Ecosystems and Human Well-being: Desertification Synthesis. World Resources Institute, Washington, DC.
[2] Pickup, G. (1998) Desertification and climate change - the Australian perspective. Climate Research 11, pp.51-63.
