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Team:Imperial College London/Project/Background
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title[5] = "Australia"; | title[5] = "Australia"; | ||
var text = new Array(); | var text = new Array(); | ||
| - | text[0] = " | + | 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 dryland 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 some 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 dryland 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 some 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[2] = "Historically, North America has experienced one of the most extreme effects of desertification during the 1930’s. 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. The use of beneficial soil microbes to improve growth of cacti has also been explored in an effort to re-vegetate deserts."; | text[2] = "Historically, North America has experienced one of the most extreme effects of desertification during the 1930’s. 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. The use of beneficial soil microbes to improve growth of cacti has also been explored in an effort to re-vegetate deserts."; | ||
Revision as of 19:07, 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.
