DESERTIFICATION: CHARACTERISTICS, CAUSES AND CONSEQUENCES - ENVIRONMENT - 2024

The desertification is the process of degradation, which lose their productive capacity and enter the wilderness condition. Deserts can be defined as a dry ecosystem (warm or cold) with low biomass and productivity.

The term desertification appeared in 1949 in a study of environmental degradation in arid regions of Africa, analyzing the transformation of forests into savannas. Later, the United Nations (UN) warned about the danger of desertification in its 1977 conference.

Desertification and deforestation. Source: Frank Vassen from Brussels, Belgium

Approximately 45% of the earth's surface are semi-arid, arid or desert areas, both low and high temperature, characterized by water scarcity. Furthermore, it is estimated that 70% of productive drylands are threatened by some form of desertification.

The causes of desertification are multiple, including both climatic and anthropic factors. Global warming is a key factor, as are the practices of intensive mechanized agriculture, cattle ranching, deforestation and the overexploitation of aquifers.

Among the consequences of desertification are the loss of biodiversity, the loss of agricultural and livestock soils, as well as the decrease in fresh water reserves. According to the FAO, there are between 3,500 and 4,000 million hectares threatened by desertification worldwide.

This surface susceptible to desertification represents about 30 percent of the continental areas of the planet, affecting about 1,000 million people.

The solutions to the problem of desertification go through achieving a sustainable development that includes conservationist agricultural and livestock practices. In addition, the reduction of global pollution and the rational use of natural resources must be achieved.

In Latin America, desertification is a growing problem and, for example, in Mexico more than 59% of its desert areas have been formed by soil degradation. In Argentina more than 75% of the surface has serious desertification threats and in Peru and Colombia 24% and 32% of their territories are affected respectively.

characteristics

- Definition

According to the FAO, it is a set of geological, climatic, biological and human factors that cause the degradation of the physical, chemical and biological quality of the soil in arid and semi-arid areas. As a consequence, biodiversity and the survival of human communities are endangered.

General view of the Sahara. Source: NASA

In addition, humid areas are also affected by the phenomenon of desertification, especially tropical forests. This occurs due to the characteristics of soil fragility and the nutrient cycle.

Therefore, in ecosystems that maintain a delicate balance based on vegetation cover, their drastic alteration is the cause of desertification. An example of this is the rainforest, such as the Amazon, where the cycle of nutrients is in biomass, including the layer of litter and organic matter in the soil.

When an area of ​​this ecosystem is deforested, the erosive action of rain carries away the fragile layer of soil. Therefore, in a short time it desertifies and has a low regeneration capacity.

- Dry zones

Dry areas susceptible to desertification cannot be defined only in terms of precipitation, but temperature must also be considered. For its part, temperature determines the evaporation rate and, therefore, the availability of water in the soil.

In the case of cold deserts, low temperatures make part of the water in the soil unavailable due to freezing.

Aridity index

To define these dry areas more precisely, the United Nations Environment Program (UNEP) has established an aridity index. This is calculated by dividing the annual precipitation by the annual evaporation potential.

Dry areas have aridity indices equal to or less than 0.65 and, based on this, 10% of the earth's surface is defined as dry. Furthermore, 18% is semi-arid, 12% is arid and 8% is hyper-arid.

In general, in a dry zone the combination of temperature, humidity and soil fertility can only support sparse vegetation and low biomass. They are areas in a limit of conditions for the support of life, so any alteration has serious consequences.

- Desertification

The desertification process threatens in a direct proportion to the aridity of the area. In this sense, we have that the more arid, the more susceptible is the area to desertification.

Acting factors

In desertification, a series of interrelated factors intervene in a complex way, affecting the fertility and physics of the soil, thus reducing productivity. As a consequence of this, the vegetation cover is lost and the soil is affected by further erosion.

The process can begin due to deforestation in an area with a fragile soil and therefore will be reflected in erosion problems.

Triggering causes may be increased temperature, decreased water availability and increased salinity or soil contamination.

- Most susceptible areas

The dry areas of the earth are the most susceptible to desertification due to the phenomenon of global warming. Therefore, dry areas become semi-arid or even hyper-arid.

Subsequently, the areas most susceptible to desertification are those close to the limits of dry ecosystems.

Figures

There are currently more than 100 countries with desertification problems, affecting nearly one billion human beings and 4 billion hectares in danger.

It is estimated that about 24,000 million tons of fertile land are lost annually by this phenomenon. In economic terms, the losses are approximately $ 42 billion.

In terms of location, 73% of agricultural drylands in Africa are moderately or severely degraded, while in Asia 71% of its area is affected. For its part, in North America, 74% of its drylands face desertification problems.

In Latin America around 75% of their lands are affected. While in Europe, one of the most affected countries is Spain with 66% of its territory. One of the most extreme cases is Australia, where 80% of its fertile lands face serious threats of desertification.

- Ecological difference between a desert and a deserted area

Desertification does not refer to the natural formation of natural dry ecosystems, since these have evolved under severe conditions, with soil and climate instability. For this reason, natural dry areas are very resilient (with a high capacity to recover from disturbances).

On the other hand, areas subject to desertification are ecosystems that have reached a balance and their development conditions are drastically varied. This alteration of their equilibrium conditions occurs in a relatively short period of time.

This is why the areas affected by desertification have a low capacity for recovery and the losses of biodiversity and productivity are very great.

Causes

The soil is degraded by loss of its physical properties, fertility, or contamination. Likewise, the availability of quality water is another relevant element that affects soil productivity.

On the other hand, it is important to consider that the vegetation cover provides protection against the erosive effects of water and wind.

In the case of tropical rainforests, most of the nutrients are in biomass and the topsoil with decomposing organic matter and mycorrhizal systems (symbiotic fungi).

Therefore, any natural or anthropogenic factor that alters the vegetation cover, structure and fertility of the soil or the water supply, can generate desertification.

- Responsible processes

At least seven processes responsible for desertification have been identified:

1. Degradation or loss of the vegetation cover.
2. Water erosion (loss of soil due to water dragging).
3. Wind erosion (loss of soil due to wind drag).
4. Salinization (accumulation of salts by irrigation with saline water or dragging of salts by infiltration)
5. Reduction of soil organic matter.
6. Compaction and formation of crusts in the soil (generates problems of water infiltration and access to groundwater by vegetation).
7. Accumulation of toxic substances (eliminating the vegetation cover).

These factors act in combination and are triggered by human actions or natural phenomena. Among these actions or phenomena we have:

- Deforestation

This is one of the direct causes of desertification, because the vegetation cover is eliminated, leaving the soil exposed to the erosive action of water and wind. Deforestation can occur to incorporate new lands for agriculture and grazing, for timber extraction, or for urbanization or industrialization.

It has been estimated that of the 3 billion trees on the planet, about 15 million are cut down annually. Additionally, in tropical forests or mountain ecosystems, deforestation causes serious problems of soil loss due to erosion.

- Forest fires

Vegetation fires remove the vegetation cover and deteriorate the organic layer of the soil, affecting its structure. Therefore, the soil is more susceptible to erosive processes due to the action of water and wind.

Similarly, fires negatively affect soil microflora and microfauna. They can be caused by both natural and anthropogenic causes.

- Mining and oil

In most cases, mining involves the eradication of the topsoil and drastic disturbance of the soil. On the other hand, the solid waste and effluent generated are highly polluting of the soil and water.

As a consequence of this, the loss of productivity of the soil and even the soil itself occurs, causing desertification.

For example, in the jungles and savannas south of the Orinoco River, in Venezuela, open-pit mining of gold and other minerals has deserted nearly 200,000 hectares. In this process, physical damage has been combined with contamination by mercury and other elements.

- Farming

The growing need for food production and the economic benefits produced by this activity intensify agriculture and therefore desertification. Modern agriculture is based on monoculture in large areas, with intensive use of agricultural machinery and agrochemicals.

Agricultural activities include a series of steps that lead to soil degradation:

Clearance

In virgin areas or on fallow or fallow land, agriculture generates deforestation or clearing, so the soil is exposed to erosion processes.

Land preparation

Depending on the crop, the soil is subjected to plowing, harrows, subsoilers and a whole series of processes. This causes the structure to be lost and makes it more susceptible to erosion.

In some cases, excessive mechanization generates soil compaction called "plow layer." Therefore, water infiltration is reduced and the root development of plants is hindered.

Irrigation

Saline water or water contaminated with heavy metals salinizes or acidifies the soil, reducing the amount of biomass. In the same way, the soil is exposed to the erosion process

Fertilizers and pesticides

The excessive use of inorganic fertilizers and pesticides biologically impoverishes the soil and pollutes the waters. The microflora and microfauna of the soil disappear and the vegetation cover is lost, so the land loses productivity.

- grazing

Overgrazing causes desertification as large areas of vegetation are deforested to establish animal production systems. This practice generates soil compaction, decrease in vegetation cover and finally erosion.

Overgrazing and desertification. Source: Cgoodwin

In mountain areas with an excess of animal load, you can see areas where the ground is exposed by the passage of animals. Therefore, it can be easily washed away by water and wind.

- Overexploitation and contamination of aquifers

Overexploitation of aquifers

The overexploitation of water sources is the cause of desertification. This is because aquatic ecosystems depend on a series of processes associated with bodies of water.

Excessive exploitation of aquifers beyond their recovery capacity causes drought and affects biodiversity. For example, plant species with radical systems that reach the water table (groundwater layer) may eventually disappear.

Water contamination

When water is polluted by various elements, it can affect ecosystems. Therefore, when water sources are contaminated, the vegetation cover disappears and the desertification process begins.

- Global warming

The increase in global temperature contributes directly to desertification due to increased evaporation and less water is available

In general terms, climate change alters rainfall patterns, prolonging droughts or causing torrential rains. Therefore, the stability of ecosystems and especially the soil is affected.

Consequences

Biodiversity

Desert areas have low biomass and low productivity because in them the essential conditions for life are at the limit of what is required. In this sense, desertification causes the loss of conditions necessary for life and, therefore, the disappearance of species.

Food production

The ability to produce food of agricultural and livestock origin decreases due to desertification processes. This is a consequence of the loss of fertile soils, a decrease in available water and an increase in temperature.

Every year around 24,000 million hectares of fertile soil are lost worldwide.

Water reserves

The capture of water, the infiltration and its conservation is directly related to the vegetation cover. Therefore, in soils devoid of vegetation, runoff and soil carry-over increases and infiltration decreases.

Furthermore, desertification causes a decrease in drinking water sources, which in turn affects other areas.

Global warming

Desertification becomes a feedback factor in the warming process. In the first place, the loss of vegetation cover affects carbon fixation and increases its concentration in the atmosphere.

On the other hand, it has been determined that the albedo (ability of a surface to reflect solar radiation) is greater in an unprotected soil than in one covered with vegetation. In this sense, the greater the area of ​​soil discovered, the warming increases as well as the radiation of heat to the atmosphere.

Solutions

- Awareness

The causes that generate desertification are closely linked to human productive processes that involve economic and even survival interests. For this reason, the awareness of the actors involved in the actions that can generate desertification is essential.

Conservationist agricultural and livestock practices should be promoted, as well as the enactment of laws to protect the soil, vegetation and water. For this, it is necessary that both the common citizen and national governments and multinational organizations participate.

- Agricultural methods

Minimum tillage

Minimal tillage methods produce less soil disturbance and thus soil structure is preserved. These practices help prevent soil losses due to erosion.

Associated crops and protective covers

Associated crops and polycultures are strategies that allow diversifying the plant cover on the ground. In this sense, the use of thatch covers or biodegradable plastics also prevent soil erosion by rain and wind.

Barriers and contour cultivation

In mountainous areas or with somewhat steep slopes, containment barriers should be established in the form of live barriers (hedges, vetiver or lemongrass). Likewise, construction walls can be placed in order to prevent the dragging of the soil runoff.

Also, contour agriculture that follows contour lines is essential to avoid soil erosion in mountain agriculture.

- Irrigation water quality

It is essential to prevent the salinization of soils and their contamination with heavy metals. For this, the various sources of pollutants ranging from acid rain to industrial discharges and agricultural waste must be controlled.

- Protection of ecosystems and revegetation

First, ecosystems must be protected from deforestation and vegetation recovery plans must be established in the affected areas. In addition, it is convenient to implement practices that reduce erosion.

- Greenhouse effect gases

It is of great importance to mitigate global warming because it accelerates the desertification processes. Therefore, it is mandatory to reduce greenhouse gas emissions into the atmosphere.

To achieve this, it is necessary to develop national and international agreements that guide the production model towards a sustainable economy.

Desertification in Mexico

More than half of the Mexican territory is made up of arid zones that reach nearly 100 million hectares. More than 70% of the national territory is affected by various levels of desertification.

Likewise, approximately 59% of desert areas have originated from soil degradation. Among the activities that most contribute to generating desertification in Mexico are overgrazing, deforestation, tillage methods and poor soil management.

In regions such as San Luís, Morelos, Hidalgo and Querétaro, there is severe and very severe wind erosion affecting about 1,140 km2. On the other hand, in Baja California, Sinaloa and Tamaulipas the biggest problems are due to salinization of the soils.

Deforestation affects large areas of the Yucatan peninsula, Campeche, Veracruz, Nayarit and Oaxaca, where around 340 thousand hectares are lost per year.

Desertification in Argentina

Argentina is the Latin American country most affected by desertification, since 75% of its surface suffers some degree of threat. According to data from the National Action Program to Combat Desertification (PAN), 60% have a moderate to severe risk and 10% are at serious risk.

This corresponds to more than 60 million hectares subject to erosive processes, and each year about 650,000 hectares are added. One of the most threatened regions is Patagonia, mainly due to overgrazing and misuse of water resources.

During 1994, Argentina signed the United Nations Convention to combat desertification. Likewise, in 1997 the diagnosis of the National Action Program to Combat Desertification was completed.

Desertification in Peru

The main causes of desertification in the country are overgrazing and water and wind erosion in Andean areas. Salinization is also affected by inadequate irrigation techniques on the coast, as well as illegal logging in the jungle.

In Peru, 40% of the coastal lands suffer from salinization problems and 50% of the soils of the sierra have serious erosion problems. In addition, 3% of the country's surface is already desertified, while 24% is in the process of desertification.

Among some of its policies to solve the problem, the country signed the United Nations Convention to combat desertification.

Desertification in Colombia

In this country, 4.1% of the territory is already affected by desertification and, of this percentage, 0.6% reaches extreme levels of severity and unsustainability. In addition, 1.9% present moderate levels of desertification and the remaining 1.4% are mild.

Additionally, 17% of the territory presents symptoms of desertification and 15% is vulnerable to suffering it.

To face the problem, Colombia is a signatory to the United Nations Convention to Combat Desertification. In addition, it has developed its National Action Plan to Combat Desertification.

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