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Land Thirst

Desert

     Desert     

Deserts are regions that receive very little precipitation — an average annual rainfall of less than 250 millimetres (10 inches). They cover more than one third of the world’s land area. This does not mean that this huge land area is barren and lifeless. Rather, deserts have high biodiversity! The flora and fauna are well-adapted to the harsh conditions.

The plant cover is sparse but enormously diverse. Most plants are drought and salt tolerant (like Xerophytes). Cold deserts mainly have grasses and shrubs. All of them, including the animals, play a vital role in maintaining balance in this delicate ecosystem. This means deserts are not bad but crucial in sustaining the balance in nature. Then how can desertification be a threat to environment?

Well, because desertification is not the expansion of existing deserts. The presence of a nearby desert has no direct relationship to it! It is the degradation of a formerly productive land, where crops could have been grown. And unlike deserts, ‘desertified’ land can support no vegetation — it is infertile and devoid of life.

     Desertification    

Landforms like mountains separate deserts from the surrounding less arid areas. In some areas, the desert borders gradually change to a more humid environment. These transition zones have very fragile ecosystems. The degradation of lands in these arid, semi-arid, and dry subhumid areas is called Desertification.

For example, seven thousand years ago the Thar Desert received abundant rainfall, hosted shrubs and trees like Jamun, and had rivers and lakes! So how did the fertile Thar turn to thorns? Because of us! And to a very small extent due to climatic variations.

Human activities

Humans settle on productive lands to grow crops and graze livestock. But, over-farming and over-exploitation of resources like groundwater diminishes the fertility of the lands. Deforestation and over-grazing add to the trouble by reducing the lands’ tree cover.

The soil is exposed to wind and water causing soil erosion. When this topsoil is eroded, the salts present in the land come up to the surface, preventing further growth of the trees. This is called salinisation (as evident in the Rann of Kachchh). The conditions are worsened by rapid urbanisation, industrialisation and poor land management systems.

Natural

Sand dunes, moving with wind, may cause desertification. In a major dust storm, dunes may move tens of metres! For example, linear dunes of the Sahara Desert encroach on Nouakchott, the capital of Mauritania in northwest Africa. Some climatic changes may even be set off by land degradation caused by human activities.

Droughts do not cause desertification. Well-managed lands can recover from it when rains return. However, land abuse during droughts can cause land degradation.

And…

The outcome is clear — loss of the rich biodiversity and the productive capacity of the entire area, leading to massive displacement of people. Over 250 million people are directly affected by desertification, and some one billion people in over one hundred countries are at risk (Source: United Nations Convention to Combat Desertification).

   Indi-facts    

  • Drylands comprise of about 223 million hectares of arid, semi-arid and dry sub-humid regions.
     
  • At least one-third of the total area is degraded (including desertified).
     
  • Arid areas (49.5 mha) are the worst affected, especially the western part of Rajasthan state (including the Thar Desert), and the arid Gujarat (including the Rann of Kachchh).

The causes are similar — recurrent droughts, high wind, dumping of mine and industrial wastes, high demand for food, fodder and fuel wood causing over-exploitation of resources, resulting in wind and water erosion, and salinistion. Traditional practices of sustainability and conservation of resources, with mixed farming (combining perennial trees and grasses with crop cultivation and livestock rearing) are dying. Thus, even traditionally “green” areas like Punjab are falling prey to desertificatio

   Degrading cycle   

  • Removal of vegetation
     
  • Erosion of soil’s top layer
     
  • Increase in the rate of evaporation with the removal of shade
     
  • Drawing up of salts to the surface (called Salinisation)
     
  • Inhibition of plant growth
     
  • Less moisture retention in the land
     
  • Change in the climate pattern leading to lower rainfall
     
  • Disappearance of the remaining plants


     Desert Combat    

So what are we doing to tackle desertification? India has embarked upon a national policy to bring 33 per cent of the country’s land area under forest. It would also implement desert and drought-prone area development programmes, including sand dune stabilisation, wind erosion control and salinity control. Many other countries have tried various solutions to reduce the rate of desertification and regain lost land including Biodiversity Action Plans. Here are a few solutions:

  • Crop rotation (growing different types of crops in the same land in sequential seasons) is a brilliant method of restoring land fertlity. It balances the fertility demands of crops, avoiding depletion of soil nutrients. Planting leguminous plants that extract nitrogen from the air and fix it in the soil is another way.
     
  • Only those crops that require less water should be planted. Cultivation of cash crops like cotton, which require a lot of water, should be prohibited in arid regions like Rajasthan.
     
  • Water resources should be efficiently used, especially by improving irrigation facilities in arid and semi-arid lands.
     
  • Rainwater harvesting would also make a huge difference. It will not just provide water for domestic uses and irrigation; it would also replenish groundwater levels.

The crux of combating desertification lies in the wise use of the existing resources.

Deserting world

  1. In the 1930s, overgrazing and drought transformed parts of the Great Plains in the United States into the “Dust Bowl”. The term desertification was not coined until around the mid twentieth century.
     
  2. The 1968 drought in Sahel, West Africa, combined with the land-use practices caused the deaths of more than 100,000 people and 12 million cattle by 1973.
     
  3. About seven per cent of Madagascar’s central highland plateau land mass has become barren.
     
  4. The Rio Puerco Basin of central New Mexico is one of the most eroded river basins of the western United States owing to overgrazing. Overgrazing is also an issue with some regions of South Africa such as the Waterberg Massif.
     
  5. The Desert of Maine is a 40-acre dune of glacial silt. Overgrazing and soil erosion exposed the cap of the dune, revealing the desert as a small patch that continued to grow, overtaking the land.
     
  6. Ghana, Afghanistan, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan are losing land to desertification.
     
  7. Nigeria, slightly larger than Texas, is losing 1,355 square miles of rangeland and cropland to desertification each year.
     
  8. Desertification is widespread in Brazil, Mexico and many areas of the People’s Republic of China.

 

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