The Concept of Desertification The concept of desertification was introduced in the late forties to designate a number of ecological degradation processes in tropical Africa, in particular the progressive transformation of tropical forest in Savana has or ever drier ecosystem. Since, then the world has received a number of other meanings. Some of them are contradictory while most of them ambiguous. The point is that each user of the concept should probably design a definition for his/her own use, depending on the goal, among other things.
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The Concept of Desertification The concept of desertification was introduced in
the late forties to designate a number of ecological degradation processes in tropical Africa, in particular the progressive transformation of tropical forest in Savana has or ever drier ecosystem.
Since, then the world has received a number of other meanings. Some of them are contradictory while most of them ambiguous.
The point is that each user of the concept should probably design a definition for his/her own use, depending on the goal, among other things.
The term desertification has been accepted with mixed blessing from the various scientists, communities and researchers that it has received a number of contradictory definition and meaning.
It is therefore difficult to start talking about desertification without bias.
Simply desertification is composed of desert and fication which literary means making of or production of the desert.
From this definition, we can feel easy for defining desertification but it has not touched the main problem, which is not to clarify what a desert is!
But for most standard dictionaries the verb to desert means to abandon and adjective 'desert' describes an uninhabited region, and the noun desert refers to a bare or waterless land.
From this point of view, desertification becomes the creation or maintenance of barren or waterless region and/or the process of abandoning a region.
This is not an end but a starting point and acceptable to most interested researcher on desertification.
Environmental degradation is very old problem for human civilization. People have been living in the drier regions of the word for centuries.
In 1949 Aubreville introduced the word desertification. As a forest expert, he was observing the progressive replacement of tropical and sub-tropical forest in Africa by savannas, a process he first termed savanization.
He identified both fire and deforestation by local people as the disturbing mechanism that allowed more arid condition to set in, and used the term desertification to designate extreme causes of savanization characterised by severe soil erosion, changes in the physical and chemical properties of the soils, and invasion of more xeric plant species.
In the early 1950s UNESCO launched the very ambitious Arid zone research program that gave series of publication and first encyclopaedia which had a major impact on knowledge and perception of dry areas.
During 1960s the rainfall levels and the timing and duration of the rainy seasons in the Sahel started to shift and resulted in very severe drought condition that become clearly identifiable in 1968.
This draught has focus attention for a number of years. In the early and mid 70's it became clear that drought only was not the only or even the main cause of the extensive disasters.
Since, the connection with desertification was made with environmental degradation but also because a wider concept than drought was required to describe the multiple aspect of the problem.
In parallel to this, a rising interest in environmental conservation and quality of life became evident in the developed world.
The movement lead to the Stockholm conference on the environment 1972 and creation of UNEP.
The same year was very unusual climatic year for many reasons: oil crisis, natural disaster, drought, flood etc. considering the magnitude of the problem in Sudan, in 1974, UN general assembly have created UN office at Sudan and ordered UNEP to organize and international conference on desertification.
In 1977, the UN conference held in Nairobi. In preparation for the conference, number of studies and documents were produced, which have helped to synthesize the problem of desertification.
The conference has adopted action plan to combat desertification, which was an attempt at identifying the problem and proposing way and means to avoid or alleviate the consequences of desertification.
Since 1979 some countries have adopted similar plans of action in the framework of their national development plan, but progress at combating desertification worldwide has been generally slow or ever non-existent.
• One must realized that desertification is by far not the only word used in the literature to describe environmental degradation in arid region. A number of word proposed for this purpose.
Term Author, Researcher PerceptionDessification Hubert 1917 Progressive drying of the
climate, particularly in the margin of
Bovalization Aubreville 1947Savanization Aubreville 1949Desertification Aubreville 1949Desertification Le Houerou 1959 Ecological degradation in any
kinds of Environment including tropical forests
Desertization Le Houerou 1959 Semi-desertic areas boundering actual deserts
Aridization Seminar Participants 1975Aridification A team of American
scientist 1977Crypto-desertification
UNCD 1977
Xerotization Kovda 1980
Different author often assign different meaning to the same word and the different word for the same thing. Here are the some definition and their emphasis.
Deforestation is the impoverishment of arid, semi-arid and some sub-humid ecosystem by the impact of men's activities. Desertification is the result of land abuse (Garduno 1977) (Emphasis of Human Land use)
Natural deserts are widespread over the surface of the earth. Their extent fluctuated in the quarterly period but exhibited a general inclination to increase. This is the process of natural desertification of former meadows, prairies, steppes and alluvial plains (Kovda 1980) (Emphasis on geological time scale phenomenon)
Desertification has been defined as the extension of typical desert landscapes and landforms to areas where they did not occur in the recent past. The world desertification has been and still is used by many authors to describe degradation of various types and forms of vegetation including the sub-humid and humid forest areas which have nothing to do with deserts either physically or biologically (Le houerou 1977) (Emphasis on Land forms and vegetation)
Desertification is the diminution or destruction of the biological potential of the land , and can lead ultimately to desert like condition. It is an aspect of the widespread deterioration of ecosystem and has diminished or destroyed the biological potential of land i.e. palnt and animal production, for multiple use purposes at a time when increased productivity is needed to support growing population in quest of development (UN 1978). (Emphasis on Economic Impact).
Point of Unclearness and Controversies1. Whether the process of desertification is reversible or
not?
• We consider desertification as being the ultimate and irreversible degradation status of fragile environment long subject to an aggressive climate and heavy human pressure.
• This may be contrasted with the view of the UN plan of action 1978 that the immediate goal of the plan of action to combat desertification is to prevent and to arrest the advance of desertification, and , where possible to reclaim desertified land for productive use.
2. Where the concept of desertification is applicable• Aubreville (1949) used this word for describing
degradation process all over Africa, including in the equatorial forest.
• Houerou introduced desertization to designate those processes occurring along the boarder of actual deserts, primarily in regions of mean annual precipitation between 100 to 200 mm.
• Rapp (1974) proposed to expand the applicability of the concept of desertification to both arid and semi-arid region receiving up to 600 mm of mean annual rainfall.
• Finally Meckelein (1980) also uses the term desertification to describe the stress on and degradation of oases inside the Sahara itself and edited a book on Desertification in the extremely arid environment.
3. How Fast is desertification Progressing?• Stebbing (1935) estimates at the time was that the Sahara was
advancing southward at the rate of one kilometre per year.
• Jone (1938) however made a critical study of Stebbing's finding and found little or no evidence for any pregression of the Sahara.
• Lampy (1975) found evidence for a 5.6 kilometer per year advance of the desert in the Sudan. At the time of conference the most popular findings is 1300 sq. km per year in Sudan and 50,000 sq. Km globally.
• Finally Simon (1980), in a review article, questioned the validiuty of the evidence and suggested that since cultivated area globally increased by one percent per year between 1950 to 60 there might be no problem et all. However, today the desertification is becoming worldwide and the strength and magnitude of the desertification is varied over space and ever increasing.
4. Author do not agree better on the causes of desertification
El-Baz (1983) views desertification as the result of a progressive drying of the climate of Africa, a trend that began 5000 years ago.
On the other hand, Dregne (1984) considers desertification to be a man induced global phenomenon that has no respect for climatic zones. Most author would fall somewhere in between, often discounting the role of climatic because it is unknown or uncontrollable.
For example Reining (1978) recognizes that if desertification is a phenomenon that involves climate, soils, flora fauna and man, it must be regarded as a form of degradation of ecosystem due to a change in the pressure of the human use of these systems.
If the authors do not agree on the cause of desertification then they are off course not agree with what to be done.
• The problem here is that desertification is neither drought, nor soil erosion, nor the destruction of vegetation cover, nor the cutting of trees, nor even the degradation of the living condition alone: It is all that and much more. So, in the absence of unique and acceptable definition for all, here are the ingredients that are most important to include or discuss explicitly when defining desertification.
1. Who will be using the definition: A politician, A farmer, Pastoralist or a environmental economist?
2. For what purpose do we need the definition: academic research, economic development, aid program or ecological preservation?
3. Where is desertification taking place: Global, continental, regional or Local? Similarly it is spatially homogenous over the region of interest, or, rather, localized to limited spots.
4. How is desertification occurring? Slow, progressive destruction of the environment, or catastrophic event?
5. What is the nature of Issue: socio-economic disruption, ecological change, land degradation?
6. What are the main factors of process involved: Overgrazing, deforestation, bad agricultural practices, soil erosion, drought, water logging, salinization.
7. What are the appropriate indicators for desertification: albedo, Vegetation cover, soil depth, livestock composition, human health and average revenue.
8. Is desertification considered to be a natural process, or man made or Both: Would desertification occur in the absence of human intervention or not?
9. Is desertification reversible or not: very controversial one? Is reversible means to back to the previous state of environment or the process should stop and go back to the previous rate? How long to back, what is the exact line to be back? Many more things, which should be define purposively before defining it.
• Finally two major things which should not include while defining desertification for the present context.
1. One is desertification should not define in terms of desert because either it is not clear what exactly is desert or it is not only place for desertification.
2. Another is we should avoid arid, semi-arid, desert of semi-desert region while defining desertification. It should be in any feature of landscape and any where.
Some Definitions• Desertification is a process of deterioration, destruction or
denudation of an ecosystem under the changing pressure of human land use. -R.A. Chaurasia
• Conversion of a grassland or an already arid land into a desert through indiscriminate human actions magnified by droughts. Such actions include overgrazing, repeated burning, intensive farming, and stripping of vegetation for firewood. See also deforestation.
(Business Dictionary)
Desertification is the degradation of land in drylands. Caused by a variety of factors, such as climate change and human activities, desertification is one of the most significant global environmental problems (Wikipedia).
• Any environment whose potential evapo-transpiration greatly exceeds precipitation is vulnerable to desertification
Indicators of Desertification
From the above discussion, it is clear that desertification has various forms, nature and dimensions. Physical, biological as well as socio-economic indicators are the major own. Various indicators of this phenomenon are listed below:
• Appearance/increase in frequency/severity of dust sandstorms/dune formation and movement
• Extend of Saline Depression
• Extend of Gravelly and Sandy land
Edaphic IndicatorsDecrease in soil depthDecrease in soil organic matterDecrease in soil fertilityIncrease Salinization/alkalinization
Meteorological IndicatorsRainfall distributionVariability of RainfallHigh Temperature differenceWater balance (P = E + R) precipitation, evaporation, runoffShorten Water availability periodIncrease in Drought intensityIncrease in Dust StormHigh wind Velocity due to low vegetation cover
HydrologicalSurface drainage density
Underground water level
Decrease water surface (lake, pond)
Brackishness of underground water
Biotic IndicatorsVegetation densityAbove ground biomassAlteration of key speciesChange in any food chainDecline the production of species
Failure of species successfully to reproduce
Decrease in forest cover
Anthropogenic IndicatorsOvergrazing
Deforestation
Increase population
Change in land use
Change in settlement patternMigrationDecrease in income and assetIncrease conflict among different groups/tribes
The UNCED defined desertification as land degradation in the arid, semi-arid, and sub-humid areas resulting from various factors, including climatic variations and human activities.
These areas are subject to serious physical constraints linked to inadequate water resources, low plant formation productivity, and general vulnerability of biological systems and functions.
Whereas on an individual basis animal and plant species are each a model of adjustment and resistance, ecological associates and formations are easily disturbed by the pressures exerted by rapidly growing populations and their livestocks.
Desertification has become a longstanding and increasingly severe problem in many parts of the world, and in developing countries in particular.
Magnitude and Trend of Desertification• One third of the earths total land surface is threatened by
desertification• Among the earth’s dry land
Severly0.5%
badly18.0%
moderately29.5%
slightly52.0%
• 35 % earth land surface and livelihood of 850 million are under threat by desertification (UNDP)
• Each year about 21 million hectare land reduced to near or complete uselessness
• According to the UNESCO Africa has been badly affected
• Majority of dry land areas are rangeland (73%)
• Rangeland and Agriculture land is mostly affecting. Among 126 million hectare land about 27.1 million hectare is significantly desertified.
• Among 13 million sq. km 4 million Km food producing land damaged by desertification.
• South Asia 70 percent land desertified in one or other level or severity.
Desertification affects nearly one billion people, or 1/6th of the world population
Desertification is occurring in 70 % of all drylands, or 25 percent of earth’s land
Desertification causes widespread poverty, and is responsible for much of the migration in the developing world.
Each year, the planet loses 24 billion tons of topsoil. Over the last two decades, enough has been lost to cover the entire cropland of the US.
Desertification is especially severe in Africa, where two-thirds of the continent is desert or drylands, and where 73 per cent of its agricultural drylands are already seriously or moderately degraded.
Asia contains the largest amount of land affected by desertification of any continent-just under 1,400 million hectares.
Nearly 2/3 of Latin America's drylands are moderately to severely desertified.
Desertification costs the world more than $40 billion a year in lost productivity.
Cause and Processes1. NATURAL CAUSES
• Drought
• Natural Disaster
• Climate change
• Pest or disease outbreak
• Difficult to avoid but can mitigate/forecast
• Drought--- insufficient moisture to meet demand of plant & livestock
– Meteorological drought----low level of rainfall
– Agricultural drought----- farmer alter crop that needed more moisture
– Hydrological drought--- absorption & storage of soil capacity change
Droughts are not restricted to a particular environment although they are common to some of the environment
Drought can lead desertification but desertification can occur without drought
Vegetation may suffer from drought or drought may arise due to damage of vegetation
2. Human Cause (Anthropogenic )
• Human Ignorance
• No policy measure,
• Inappropriate policy
•Overgrazing
• Intensive use of agricultural land
• Deforestation
• Poor irrigation practice
• Inappropriate land use
• Poverty
• Forest fire
• Population Growth
• Socio-Economic Structure and relation (ownership, access and control of resources)
• Political economic causes (Local vs Global) Globalization and Desertification
• Resource Exploitation
• Technology (Nuclear testing)
• Much damage has been inflicted on the economic activities in the arid regions, leading to a great deal of hardship for the majority of the people there. Very few parts of the arid zone have been spared. What accounts for this unhappy situation? The answer is twofold.
• Firstly, human pressure in the dry zones has grown enormously in recent decades owing to an increase in population. The needs for food, water, fuel, raw materials, and other natural resources have grown accordingly, exceeding the carrying capacity of the land in most cases.
• Secondly, many recent years have seen protracted drought, sometimes lasting for over 20 years. Under natural conditions, such failures of expected rainfall would have had little effect, but coupled with the human pressures they have produced disastrous results.
• Soil erosion caused naturally by prolonged droughts and by various activities that abuse and over-exploit the natural resources are, in essence, responsible for the advance of deserts.
• Advancing deserts provide negative feedbacks to the root causes, thereby accelerating the process of desertification further. Whatever the causes, the processes of degradation or desertification involve damage to the vegetation cover. So, one of the important process of desertification is loss of vegetation.
Possible solutions• In face of the social, economic, political, and environmental
problems from hazards, it is inevitable that two questions have received increased attention in recent years: Can the damage be prevented? Can the damage that has already occurred be reversed? Answer is YES
• Preventive measures for combating drought and halting the spread of the deserts, as highlighted by the UNCED in Agenda 21, include:
1. strengthening the knowledge base and developing information and monitoring systems for regions prone to desertification and drought, including the economic and social aspects of the fragile ecosystems;
2. combating land degradation through, inter alia, intensified soil conservation, afforestation, and reforestation activities;
3. developing and strengthening integrated development programs for the eradication of poverty and the promotion of alternative livelihood systems in areas prone to desertification;
4. developing comprehensive anti-desertification programs and integrating them into national development plans and national environmental planning;
5. developing comprehensive drought-preparedness and drought-relief schemes, including self-help arrangements for drought-prone areas and the design of programs to cope with environmental refugees;
6. encouraging and promoting popular participation and environmental education, focusing on desertification control and management of the effects of drought (UNCED, 1992).
• The overriding need of the next few decades is to evolve strategies that inextricably tie conservation and development together. Policies for resource management will have to include the following essential components:
• a recognition of the true value of natural resources, because they ultimately are in finite supply;
• institutional responsibility for resource management hand in hand with a matching accountability for results;
• better knowledge of the extent, quality, and potential of the resource base while accelerating the diffusion of existing technology that can expand output in environmentally sound ways.
Measure of Desertification Management
1. Research and monitoring (indigenous Knowledge, Community forestry)
2. Land Use Planning/Land Use Zonation
3. Dry land Cropping Strategies
4. Appropriate forest management strategy
5. Renewable energy technology/alternative energy promotion
6. Emphasizes on people’s participation
7. Training to the local people and desertification workers
8. Sustainable management of natural resources
9. Management and control agriculture pest and disease
10.Early warning system
11.Desertification Management Plan/policy
12.Drought preparedness and Relief Scheme
13. Desertification combat framework in national development policy
