read at :
dg Water Resources Management
Environment and People (see my Blogroll)
http://www.environmentandpeople.org/LandDegradation.html
Land degradation
Land degradation is a human induced or natural process which negatively affects the land to function effectively within an ecosystem, by accepting, storing and recycling water, energy, and nutrients. Desertification is land degradation occurring in the arid, semiarid and dry subhumid areas of the world. These susceptible drylands cover 40 percent of the earth’s surface and puts at risk more than 1 billion people who are dependent on these lands for survival. Land degradation cancels out gains advanced by improved crop yields and reduced population growth. The causes of land degradation are mainly anthropogenic and mainly agriculture related:
- The Major Causes:
- Land clearing and deforestation
- Agricultural mining of soil nutrients
- Urban conversion
- Irrigation
- Pollution
- The Major Stresses:
- accelerated erosion by wind and water
- removal of nutrients
- acidity increase
- salination
- alkalinization
- destruction of soil structure
- loss of organic matter
Severe land degradation affects a significant portion of the earth’s arable lands, decreasing the wealth and economic development of nations. The link between a degraded environment and poverty is direct and intimate.
As the land resource base becomes less productive, food security is compromised and competition for dwindling resources increases, the seeds of potential conflict are sown.
Species diversity is lessened and often lost as lands are cleared and converted to agriculture.
Thus a downward eco-social spiral is created when marginal lands are nutrient depleted by unsustainable land management practices resulting in lost soil stability leading to permanent damage.
