Desertification phenomenon

The phenomenon of "desertification" is the transformation of large areas fertile and high production into spaces
Poor in plant and animal life and this is either a reference to the brutal human treatment
Or climate change.
Desertification is a global problem affecting many countries in all regions
the world. It is defined as a decrease in the capacity of the Earth's biological production or degradation
Fertility of productive land at the rate earned by climatic conditions
The desert. Therefore, desertification leads to a decrease in the production of plant life
The total desert area in the world is about 46 million square kilometers
The Arab world, of which about 13 million square kilometers, or about 28% of the total
Desertified areas of the world.

1. Definition of desertification:
   There are many definitions of desertification, the most important of which are:

1. The United Nations Environment Program (UNEP) defines desertification as the spread and increase of conditions
   Desertification, which results in low productivity of living matter, reduces production
   Crops.
2. The International Conference defined desertification as the decline and degradation of the Earth's bioenergy
   Which leads to conditions similar to the desert, and sees Rosa Nov use the definition
   next one :
   Desertification is a non-reversible process in dry earth and vegetation leads to
   Drought and dwindling biological productivity that may end in severe cases
   The damage of the vital field and turning the earth into a desert.
   Non-inverse transformation means a change in land or vegetation that requires intervention
   To treat it or that natural processes restore it to normal state
   Although reliance on these natural processes would require generations or more
   Centuries until it is achieved.

1. Desertification Forms:
   Desertification is increasing and its impact is accelerating and accelerating for several decades in most arid zones and it takes the following forms:
   1 - shrink and decrease parts of the soil covered with plants so that the ground becomes bare
   Completely in the dry season and take the bare areas growing so that the plants become
   In the form of isolated small spots.

1. As a result of erosion, the surface of the earth becomes more resilient to solar radiation because the arid land is light colored.
   3 - large erosion of soil and loss of fertility due to the wind and carrying materials
   Organic and fast oxidation and nutrient transfer with fine granules of soil.

4 - the spread of water erosion by heavy rain.
5 - the sand dunes on agricultural lands and cities, villages and installations.

1. Water imbalance and energy balance of dry areas due to factors
   Natural or as a result of excessive human use of land.

1. Desertification cases and their impacts:
   The status of the degree of severity or deterioration of biological capacity in the environment
   Desertification varies from mild to very severe
   Other The United Nations Conference at Nairobi (1977) has identified four cases of desertification
   she:

(1) Slight desertification: the mildest cases of desertification, where no apparent damage is apparent
And the elements of life, and then it does not exceed the phenomenon and has not yet reached the extent of the problem
And then considered an acceptable case, and this usually indicates _ very slight damage research in
Vegetation and soil
Does not adversely affect the clear biological ability of the environment,
(2) Moderate desertification: This is the first case in which the seriousness of desertification emerges as a problem, as it begins
Desertification has this situation takes relatively serious dimensions where it affects the pot
Biological diversity
It usually has an average degree of recklessness in vegetation or sandy formation
Small and build small grooves or the formation of some protrusions or narcotic added to me
The occurrence of a soil salinity grade that reduces its biological capacity to produce by its proportion
Ranging from 10-50%
(3) Severe desertification: This condition is considered an advanced degree of desertification, indicating the spread
Weeds and unwanted shrubs at the expense of only desirable and desirable species,
As well as increase erosion activity sweep, whether water or wind erosion
Lead the soil

In addition to the formation of large canyons and its promises fixed sand dunes activity
Build new large sand dunes and reduce the biological (productivity) of the soil
In this case ranging from 50%, 90%
And if desertification has emerged as a clear problem in dry and semi-arid environments
And wetlands, primarily because of fragile or semi-fragile ecosystems
Fragile nature whose desertification supports and supports it but the signs of desertification have appeared
Also stand out in some Europe in the United States deteriorating its cover
And their biological potential decreases due to increased acid rain and fog
Acidity and their effect on plants and the chemical composition of the soil (increase its acidity
) And impact on production capacity
Some tropical regions have also begun to experience desertification as a result of over-exploitation
Or overgrown trees. Recall for example what is happening nowadays in the basin
Amazon's severe degradation of biological capacity.

In some areas where giant tree growth seemed to change with less intense and less growth
And some shrubs replaced the trees and the soil deteriorated clearly as a result
The activity of the soil sludge after being stripped of its vegetation.

1. The manifestations and risks of desertification:
   Desertification has many different manifestations and we can, through this phenomenon, know if
   The environment was suffering from the problem of desertification or not, and the severity or severity of the problem
   , And include this phenomenon as follows:
2. Sediment of the soil: considered one of the most serious manifestations of desertification especially when the layer is swept away
   The upper is completely given because this layer contains most nutrients
   Necessary for a plant with high capacity to drink water and kept it. And then when
   Part or all of them are washed away from so-called "physiological droughts.
3. Return of Fixed Sand Dune Activity:
   The return of fixed sand dunes, or the formation of sand dunes is active in
   Environments whose biological conditions did not qualify for the formation of such dunes of demonstration

Desertification Dangerous, sand dunes are known to be divided into two groups:
CollectionThe sand dunes are animated (living) and the group of sand dunes (dead) means the stability of sand dunes. The layer is rich in moisture and vegetative growth, which helped to stabilize and stop creeping through the growth of plants that are working to stabilize the sand. Thus, the return of the activity of the fixed sand dunes means that there is a change in the biological capacity of these dunes, which led to the disappearance of most of the protective plant cover that was working to fix them and therefore seemed to move by wind and spread desertification in the areas they invade. Sand dunes are active because they cause a lot of agricultural and upper land to be flooded with sand, leaving them completely desertified. 3) Decreased vegetation cover and deterioration of quality: Decreased area and density of vegetation cover and deterioration of the quality of desertification demonstration, as this decline and deterioration means that the biological capacity of the environment has deteriorated and began to push these areas towards the desert dry conditions has revealed from the Maghreb region that most of the forests in the The areas were destroyed during over-logging to be replaced by weed grass and the areas covered by the steppe were transformed under the weight of overgrazing and overgrazing into desert-like vegetation. The area of ​​pine forests in Tunisia declined from 300 thousand hectares to 170 Soil salinity and sedimentation: saline and salinity are also taken as an indicator of desertification. Agricultural environments in irrigated agricultural environments are artificially irrigated, as soil salinity or soil fertilization increases their productive productivity and may sometimes result in soil infertility (unproductive soil) What is happening in southern and central Iraq, where it is estimated that 1% of the area irrigated land is salted annually and become outside the productive land area and also witnessed the Qatif area in Saudi Arabia. D) Means of reducing soil erosion and desertification: especially in arid and semi-arid areas, Medicine Consciousness and development. The most important of these means: 1) Environmental survey to find out the reasons that lead to the deterioration of ecosystems. 2) Installation of sand dunes includes: a - the establishment of front and defensive barriers as the first lines in front of the progress of the sand. (B) Establishment of small windbreaks; C - Cover sand dunes as follows: - Dead plant materials. - Petroleum derivatives and chemicals or rubber. - Plantation of sand dunes suitable for the center of the sand dunes. 3) Preserving natural grasslands and developing natural vegetation cover. 4) Stop the expansion of rainfed agriculture at the expense of natural grasslands. 5) Exploitation of flood waters in agriculture. 6) Stop cutting trees and shrubs for use as an energy source. 7) Control irrigated agriculture and reconsider the current irrigation and drainage methods. 8) Dry Agriculture: Cultures of plants that require little water and are highly resistant to drought. 9) Improve soil structure by adding organic matter to it and plowing it with the plants in which it lives. 10) Elimination of the tendency of the land by establishing terraces (terraces). 11) Plowing land in the first rainy season. 12) Construction of ponds and lakes in the grooves to stop the runoff of water 13) The establishment of dams to reduce the strength of the floods. 14) Preserve vegetation and avoid overgrazing. 15) Surrounding fields and lands prone to erosion with boulders from trees and shrubs.