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Land degradation is a concept in which the value of the biophysical environment is affected by one or more combination of human-induced processes acting upon the land.1 Natural hazards are excluded as a cause, however human activities can indirectly affect phenomena such as floods and bushfires.
It is estimated that up to 40% of the world's agricultural land is seriously degraded.2
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Causes
Land degradation is a global problem, mainly related to agricultural. The major causes include:
- Land clearance, such as clearcutting and deforestation
- Agricultural depletion of soil nutrients through poor farming practices
- Livestock including overgrazing
- Urban conversion
- Irrigation and overdrafting
- Land pollution including industrial waste
- Vehicle Off-roading
- Weeds
- Walking tracks
Effects
The main outcome of land degradation is a substantial reduction in the productivity of the land.3 The major stresses on vulnerable land include:
- Accelerated soil erosion by wind and water
- Soil acidification or alkalinisation
- Salination
- Destruction of soil structure including loss of organic matter
- Derelict soil
- People walking on the land
Severe land degradation affects a significant portion of the earth's arable lands, decreasing the wealth and economic development of nations. Land degradation cancels out gains advanced by improved crop yields and reduced population growth. As the land resource base becomes less productive, food security is compromised and competition for dwindling resources increases, the seeds of famine and potential conflict are sown.
Unless land rehabilitation measures are effective a downward eco-social spiral is created when marginal lands are nutrient depleted by unsustainable land management practices resulting in lost soil resilience leading to soil degradation and permanent damage.
- See also: Soils retrogression and degradation
We often assume that land degradation only affects soil fertility. However, the effects of land degradation often more significantly affect receiving water courses (rivers, wetlands and lakes) since soil, along with nutrients and contaminants associated with soil, are delivered in large quantities to environments that respond detrimentally to their input.
Land degradation therefore has potentially disastrous effects on lakes and reservoirs that are designed to alleviate flooding, provide irrigation, and generate hydroelectricity.
Climate change
Significant land degradation from seawater inundation, particularly in river deltas and on low-lying islands, is a potential hazard that was identified in a 2007 IPCC report.citation needed As a result of sea-level rise from climate change, salinity levels can reach levels where agriculture becomes impossible.
See also
References
- ^ Conacher, Arthur; Conacher, Jeanette (1995). Rural Land Degradation in Australia. South Melbourne, Victoria: Oxford University Press Australia, 2. ISBN 0195534360.
- ^ Ian Sample (2007-08-31). "Global food crisis looms as climate change and population growth strip fertile land". The Guardian. Retrieved on 2008-07-23.
- ^ "Land: Programmes and Activities". United Nations Environment Programme. Retrieved on 2008-07-19.
- "Human Induced Land Degradation is Preventable". United States Department of Agriculture - Natural Resources Conservation Service. Retrieved on 2006-06-20. This article incorporates text in the public domain produced by the USDA Natural Resources Conservation Service
Further reading
- Eswaran, H.; R. Lal and P.F. Reich. (2001). "Land degradation: an overview". Responses to Land Degradation. Proc. 2nd. International Conference on Land Degradation and Desertification, New Delhi, India: Oxford Press. Retrieved on 2006-06-20.
- D.L. Johnson and L.A. Lewis Land Degradation:Creation and Destruction, 2nd edition, Rowman and Littlefield, Lanham, Boulder, New York, Toronto, Oxford, 2007.
Wikipedia content modification information:
- This page was last modified on 25 November 2008, at 01:46.
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