Land degradation is a process in which the value of the biophysical environment is affected
by a combination of human-induced processes acting upon the land.
Also environmental degradation is the gradual destruction or reduction of the quality and
quantity of human activities animals activities or natural means example water causes soil
erosion, wind, etc.
It is viewed as any change or disturbance to the land perceived to be deleterious or
undesirable.
Natural hazards are excluded as a cause; however human activities can indirectly affect phenomena
such as floods and bush fires.
This is considered to be an important topic of the 21st century due to the implications
land degradation has upon agronomic productivity, the environment, and its effects on food security.
It is estimated that up to 40% of the world's agricultural land is seriously degraded.
Measures Land degradation is a broad term that can
be applied differently across a wide range of scenarios.
There are four main ways of looking at land degradation and its impact on the environment
around it: A temporary or permanent decline in the productive
capacity of the land.
This can be seen through a loss of biomass, a loss of actual productivity or in potential
productivity, or a loss or change in vegetative cover and soil nutrients.
Action in the lands capacity to provide resources for human livelihoods.
This can be measured from a base line of past land use.
Loss of biodiversity: A loss of range of species or ecosystem complexity as a decline in the
environmental quality.
Shifting ecological risk: increased vulnerability of the environment or people to destruction
or crisis.
This is measured through a base line in the form of pre-existing risk of crisis or destruction.
A problem with defining land degradation is that what one group of people might view as
degradation, others might view as a benefit or opportunity.
For example, planting crops at a location with heavy rainfall and steep slopes would
create scientific and environmental concern regarding the risk of soil erosion by water,
yet farmers could view the location as a favourable one for high crop yields.
Different types In addition to the usual types of land degradation
that have been known for centuries, four other types have emerged in the last 50 years:
pollution, often chemical, due to agricultural, industrial, mining or commercial activities;
loss of arable land due to urban construction; artificial radioactivity, sometimes accidental;
land-use constraints associated with armed conflicts.
Overall, 36 types of land degradation can be assessed.
All are induced or aggravated by human activities, e.g. sheet erosion, silting, aridification,
salinization, urbanization, etc.
Causes
Land degradation is a global problem, largely related to agricultural use.
The major causes include: Land clearance, such as clearcutting and deforestation
Agricultural depletion of soil nutrients through poor farming practices
Livestock including overgrazing and overdrafting Inappropriate irrigation and overdrafting
Urban sprawl and commercial development Soil contamination
Vehicle off-roading Quarrying of stone, sand, ore and minerals
Increase in field size due to economies of scale, reducing shelter for wildlife, as hedgerows
and copses disappear Exposure of naked soil after harvesting by
heavy equipment Monoculture, destabilizing the local ecosystem
Dumping of non-biodegradable trash, such as plastics
Effects
Overcutting of vegetation occurs when people cut forests, woodlands and shrublands—to
obtain timber, fuelwood and other products—at a pace exceeding the rate of natural regrowth.
This is frequent in semi-arid environments, where fuelwood shortages are often severe.
Overgrazing is the grazing of natural pastures at stocking intensities above the livestock
carrying capacity; the resulting decrease in the vegetation cover is a leading cause
of wind and water erosion.
It is a significant factor in Afghanistan.
ext of land shortage the growing population pressure, during 1980-1990, has led to decreases
in the already small areas of agricultural land per person in six out of eight countries.
Population pressure also operates through other mechanisms.
Improper agricultural practices, for instance, occur only under constraints such as the saturation
of good lands under population pressure which leads settlers to cultivate too shallow or
too steep soils, plough fallow land before it has recovered its fertility, or attempt
to obtain multiple crops by irrigating unsuitable soils.
High population density is not always related to land degradation.
Rather, it is the practices of the human population that can cause a landscape to become degraded.
Populations can be a benefit to the land and make it more productive than it is in its
natural state.
Land degradation is an important factor of internal displacement in many African and
Asian countries Severe land degradation affects a significant
portion of the Earth's arable lands, decreasing the wealth and economic development of nations.
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.
Sensitivity and resilience Sensitivity and resilience are measures of
the vulnerability of a landscape to degradation.
These two factors combine to explain the degree of vulnerability.
Sensitivity is the degree to which a land system undergoes change due to natural forces,
human intervention or a combination of both.
Resilience is the ability of a landscape to absorb change, without significantly altering
the relationship between the relative importance and numbers of individuals and species that
compose the community.
It also refers to the ability of the region to return to its original state after being
changed in some way.
The resilience of a landscape can be increased or decreased through human interaction based
upon different methods of land-use management.
Land that is degraded becomes less resilient than undegraded land, which can lead to even
further degration through shocks to the landscape.
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.
As a result of sea-level rise from climate change, salinity levels can reach levels where
agriculture becomes impossible in very low lying areas.
See also
References
Further reading "Human Induced Land Degradation is Preventable".
United States Department of Agriculture - Natural Resources Conservation Service.
Retrieved 2006-06-20.
This article incorporates text in the public domain produced by the USDA Natural Resources
Conservation Service Eswaran, H.; R. Lal and P.F.
Reich..
"Land degradation: an overview".
Responses to Land Degradation.
Proc. 2nd.
International Conference on Land Degradation and Desertification.
New Delhi, India: Oxford Press.
Retrieved 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.