Desertification

What is Desertification?  Desertification (or

desertization) is the degradation of land in arid, semi arid and dry sub-humid areas resulting primarily from human activities and influenced by climatic variations.

 in 2000, drylands occupy nearly half of

Earth’s land area.  In drylands, water scarcity limits the

production of crops, forage, wood, and other services ecosystems provide to humans  Some 10 to 20% of drylands are already

degraded

What Causes Desertification?

 Desertification is caused by a combination

of social, political, economic, and natural factors which vary from region to region.

Causes…..  Overgrazing is the major

cause of desertification worldwide.

 In modern times, the use of

fences has prevented domestic and wild animals from moving in response to food availability, and overgrazing has often resulted.

Causes.....  The use of boreholes and windmills also allows livestock to stay

all-year round in areas formerly grazed only during the rains when seasonal pans held water.

 Cultivation of marginal lands  Destruction of vegetation in arid regions, often for fuelwood.  Poor grazing management after accidental burning of semi-arid

vegetation.

 Incorrect irrigation practices in arid areas can cause salinization,

(the build up of salts in the soil) which can prevent plant growth.

Causes…..  Increasing human population and poverty contribute to

desertification

 Policies that can lead to an unsustainable use of resources and

lack of infrastructures are major contributors to land degradation .

 The process of globalization both contributes to desertification

and helps prevent it

 Historically, dryland livelihoods have been based on a mixture of

hunting, gathering, farming, and herding. This mixture varied with time, place, and culture, since the harsh conditions forced people to be flexible in land use.

A misconception…  It is a misconception that droughts cause

desertification. Droughts are common in arid and semiarid lands. Well-managed lands can recover from drought when the rains return. Continued land abuse during droughts, however, increases land degradation.

Desertification…….  While desertification has received tremendous

publicity by the political and news media, there are still many things that we don't know about the degradation of productive lands and the expansion of deserts.  Contrary to many popular reports, desertification is

actually a subtle and complex process of deterioration that may often be reversible.

What are the effects of desertification?

 Desertification

affects the livelihoods of millions of people, as it occurs on all continents (except Antarctica).

Women often play a key role in water management in drylands (Mauritania) Source: MA

Effects……..  Desertification reduces the ability of land to support life,

affecting wild species, domestic animals, agricultural crops and people. The reduction in plant cover that accompanies desertification leads to accelerated soil erosion by wind and water.

 Water is lost off the land instead of soaking into the soil to

provide moisture for plants.

 Desertification has environmental impacts that go beyond the

areas directly affected. For instance, loss of vegetation can increase the formation of large dust clouds that can cause health problems in more densely populated areas, thousands of kilometers away. Moreover, the social and political impacts of desertification also reach non-dryland areas. For example, human migrations from drylands to cities and other countries can harm political and economic stability.

How widespread is Desertification?  About one third of the world's land surface is arid or semi-arid. It

is predicted that global warming will increase the area of desert climates by 17% in the next century.

 Worldwide, desertification is making approximately 12 million

hectares useless for cultivation every year.

 In the early 1980s it was estimated that, worldwide, 61% of the

3257 million hectares of all productive drylands were moderately to very severely desertified.

Global Monitoring  In the last 25 years, satellites have begun to

provide the global monitoring necessary for improving our understanding of desertification. Landsat images of the same area, taken several years apart but during the same point in the growing season, may indicate changes in the susceptibility of land to desertification. Studies using Landsat data help demonstrate the impact of people and animals on the Earth.

Is there a link between desertification, global climate change and biodiversity loss?  Desertification diminishes biological diversity, a

diversity which contributes to many of the services provided to humans by dryland ecosystems. Vegetation and its diversity are key for soil conservation and for the regulation of surface water and local climate. Desertification also contributes to global climate change by releasing to the atmosphere carbon stored in dryland vegetation and soils.

Countering Desertification!!!

 Desertification has been recognized as a major threat

to biodiversity. Numerous countries have developed Biodiversity Action Plans to counter its effects, particularly in relation to the protection of endangered flora and fauna.

Countering Desertification  Leguminous plants, which extract nitrogen from the

air and fixe it in the soil, can be planted to restore fertility.  Stones stacked around the base of trees collect morning dew and help retain soil moisture.  Artificial grooves can be dug in the ground to retain rainfall and trap wind-blown seeds.  In Iran, petroleum is being sprayed over semi-arid cropland. This coats seedlings to prevent moisture loss and stop them being blown away.

Countering Desertification  Windbreaks made from trees and bushes to reduce

soil erosion and evapotranspiration were widely encouraged.  Solar ovens and efficient wood burning cook stoves

are being advocated as a means to relieving some of this pressure upon the environment.

Countering Desertification  Sand fences are used

throughout the Middle East and the US, in the same way snow fences are used in the north. Placement of straw grids, each up to a square meter in area, will also decrease the surface wind velocity. Shrubs and trees planted within the grids are protected by the straw until they take root.

Trees are planted instead of sand fences to reduce sand accumulating in a UAE highway.

Countering Desertification  Oases and farmlands in

windy regions can be protected by planting tree fences or grass belts.

A row of tree fences along the highway. Plants with fine leaves can trap sand.

Countering Desertification  More efficient use of existing water resources

and control of salinization are other effective tools for improving arid lands. New ways are being sought to use surface-water resources such as rain water harvesting or irrigating with seasonal runoff from adjacent highlands. New ways are also being sought to find groundwater resources and to develop more effective ways of irrigating arid and semiarid lands.

Countering Desertification  If we are to stop and reverse the degradation

of arid and semiarid lands, we must understand how and why the rates of climate change, population growth, and food production adversely affect these environments. The most effective intervention can come only from the wise use of the best earth-science information available.

Countering Desertification

Straw grids (one of which is shown at left) and vegetation irrigated by water from the Yellow River stabilize dunes in this part of China's Tengger Desert (shown at right) and protect a nearby railroad from windblown sand.

Countering Desertification

From wasteland to vineyard. Ground water and underground channels help this vineyard flourish on land reclaimed from desert pavement in China's Turpan Depression.

Desertification in the Philippines…  In the Philippines, desertification is feared to be

presaged by seasonal aridity.

 The northern tip of Luzon, provinces in the western

portion of the country experiencing Type I climate (with pronounced dry and wet season), and major corn and feed grain-producing areas in the southern tip of Mindanao are exhibiting clear conditions similar to desertification. These areas are generally vulnerable to climatic events that contribute to soil degradation – typhoons, floods, droughts and the increasing frequency of El Niño and La Niña events.

Desertification in the Philippines…  35 years ago, Philippines had some 16 million

hectares of rainforests but was already ravaged so much, leaving only 2.8 percent today and allowing 200,000 hectares more to vanish each year.  The foremost human factors of desertification are the

overcultivated upland farms, soil erosion, land degradation, decline in productivity, kaingin system of farming, and people’s carelessness.

Philippine situationer…  About 45% of the arable lands in the Philippines have

been moderately to severely eroded triggering the movement of subsistence farmers to marginal lands with the hope of meeting their day to day food requirement.

 The most common type of land degradation in the

Philippines is soil erosion.

 Excessive use of nitrogen or urea fertilizer, noted in

soil analysis conducted since 1970, has resulted in nutrient imbalance and contributed to the actual silent soil degradation called soil mining.

Philippine situationer…  Topographic variations and problem soils also

contribute to land degradation. Problem soils characterized by steep slopes, poor drainage, coarse textures and fertility limitations are dominant in the Philippines. Volcanic eruptions also degrade the land.

 Another factor is population increase that has

resulted in the expansion of farm and residential areas to ecologically fragile lands and the increasing pressure on shrinking and degraded agricultural lands to produce more food.

Reversing Desertification in the Philippines…  In solidarity with the rest of the world, the Philippines

through the Departments of Agriculture, Agrarian Reform, Environment and Natural Resources, and Science and Technology came up with the National Action Plan (NAP) to operationalize its full and unqualified commitment to implement programs and project activities that combat desertification, land degradation and poverty in the drought vulnerable areas of the country.

Reversing Desertification in the Philippines…  Through the NAP, the government will implement

programs in sustainable agriculture and marginal upland development and integrated ecosystem management through five components. These are land and water technology development; local governance and community initiatives; data base development and harmonization; information, education and communication; and enabling policy development.

Reversing Desertification in the Philippines…  Until 2010, the government aims to establish 5,000

community learning centers to train 15,000 upland dwellers and develop community initiatives on local area management. It will also construct in critical watershed areas some 100,000 small water retention structures that will benefit one million farmers and provide jobs to another one million upland dwellers.

Reversing Desertification in the Philippines…  Farmers will be taught balanced fertilization or the

proper combination of inorganic and organic fertilizers to reduce the dependence on chemical fertilizers by 300% at the end of 2010. The government will implement programs that will prevent further expansion of land degradation and avert desertification, rehabilitate critical watershed ecosystems in Mindanao and Luzon strategic areas to improve agriculture and fisheries production, as well as rehabilitate/reestablish minor forest products.

Reversing Desertification in the Philippines…

 To escape the desert, we must stop

desertification by leaving unsustainable land use practices behind us!!!!