Deserts advance erratically, forming patches on their borders. Unfortunately and very often, an area undergoing desertification is brought to public attention only after the process is well underway. Scientists still question whether desertification, as a process of global change, is permanent or how and when it can be halted or reversed.
Increased population and livestock pressure on marginal lands has accelerated desertification worldwide. In some areas, nomads moving to less arid areas disrupt the local ecosystem and increase the rate of erosion of the land. Nomads are trying to escape the desert, but because of their wrong land-use practices, they are bringing the desert with them.
While desertification has received tremendous publicity in the news media in the recent decades, there is still lack of awareness about the degradation of productive lands and expansion of deserts.
Animal life, plant cover, and natural resources of desert lands and arid regions are very sensitive and fragile and are easily damaged by destructive factors.
Overgrazing, excessive shrub and other vegetation use as fuel and converting rangelands for agricultural purposes are three main factors which devastate pastures and strip the vegetation plant cover.
Unrestrained growth of population and hence unsparing use of plants for fuel and other irrational use of natural regulation tend to denude the soil and intensify desertification.
Denuded soil is exposed to wind erosion and shifting sand dunes destroy orchards, gardens, farming lands and threaten industrial and economic centers.
This eventually leads to total collapse of economy, devastation of the environment, abandonment of settlements and emigration of the inhabitants to other cities and residential centers, which in turn raises numerous new difficulties and problems.
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In Iran, nearly 43 million hectares of lands are exposed to erosion.
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Human Threat
Expanding human habitations and land cultivation have threatened Iran’s exceptionally rich biodiversity containing many species of fauna and flora, disrupting ecological patterns.
Basically, wind erosion control involves land salvage and re-vegetation in areas that are subjected to it because of denudation.
The results of more than 25 years of sand dune fixation activities in Iran and plantation of one million hectares with seedlings and 2 million hectares with seeds has protected or rehabilitated more than 4 million hectares of Iranian arid lands, according to Jahan-e Eqtesad daily.
Managing Director of Sand Stabilization and Desertification Office of the Forests, Pastures and Watershed Management Organization Mohammad Mousavi said Iran has carried out numerous experiments, researches, and projects for decades on sand stabilization and rehabilitation of desert lands.
He says due to Iran’s geographical situation and topographical features, about 80 percent of the country’s total area has arid or semiarid climate.
The Alborz mountain chain in north and Zagros mountain chain in west surround the central part of the country. In this central region the average annual precipitation is negligible varying from 50-250 mm and in most parts does not exceed 100 mm.
“International research studies indicate one of the most rational and efficient ways to stabilize the running sands is rehabilitation of plant cover and reclamation of ecological conditions. But since soil is not stable, sometimes it is necessary first to stabilize it temporarily against movement with windbreaks or palisades,“ says Mousavi, adding that for permanent stabilization of dunes, plant cover must be fully restored.
This, he adds, may be carried out through seeding, plantation of seedlings, and cuttings which requires seeds be partly obtained from other planted areas and partly from natural forests or deserts.
The required seedlings are grown in nurseries either in seed beds or plastic pots.
In Iran, nearly 43 million hectares of lands are exposed to erosion. Sand erosions constitute between 10-20 percent resulting from natural disasters (earthquake, floods, drought). Residential units, industrial structures and infrastructures sustain 45.7 percent of the damages, in addition to 44.3 percent of farmlands and some 10 percent of environmental resources, especially pastures.
According to Mousavi, land degradation and desertification in Iran have accelerated during recent decades due to factors such as rapid population growth, while more agricultural and pastoral products have forced people to use land extensively or convert forest and rangelands to cultivated land.
Irregular and uncoordinated exploitation of water resources is another contributing factor.
The policies and programs to rehabilitate and develop renewable natural resources, with consideration for desertification control include socio-economic development in rural areas (to prevent the migration of farmers to major cities (Tehran, Shiraz, Isfahan, Tabriz), conservation of water resources including Qanats (underground water canals) and water supply installations, protection of roads and communications networks.
Protecting the environment, restoring the ecological stability, reclamation and rehabilitation of degraded lands, sand dune stabilization to minimize negative effects on farmland are among measures the government says it has been taking to restrain the phenomenon and lessening its effects.
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Desertification has received tremendous publicity but there is still lack of awareness about the degradation of productive lands.
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Global Threat
Desertification is a global concern not limited to specific geographical regions. Desertification has become a longstanding and increasing problem in many parts of the world, in developing countries in particular.
In fact in Iran, wind erosion and its effects on natural resources and the environment has been a serious problem for the last 25 years.
Expansion of communication networks, construction of large dams, failure to assist the poor, and natural disasters such as fire and drought have further aggravated the problem. Desertification and deforestation involve a drastic change in microclimates. Global warming and the greenhouse effect also have their origin in deforestation and desertification.
Deforestation and desertification adversely affect agriculture productivity, the health of humans as well as of livestock, and undermine the economy by adversely affecting as eco-tourism.
To halt desertification the number of animals on the land must be reduced, allowing plants to grow again. Soil conditions must be made favorable for plant growth by, for example, mulching. Mulch (a layer of straw, leaves or sawdust covering the soil) reduces evaporation, suppresses weed growth, enriches soil as it rots, and prevents runoff and hence erosion. Reseeding may be necessary in badly degraded areas. Mulching and reseeding are expensive practices.
Ultimately, the only realistic large-scale approach is to prevent desertification through good land management in semi-arid areas.
