Deserts
Desert status in Iran
Desert is a familiar word for Iranians as this word always reminds us of an arid area that has very few plants and very little water and is without suitable conditions for living. Desert has been defined differently in different cultures, for instance in ancient Persian the word Viapan means waterless area. In Arabic the word Sahara implies a desert area and in Urdu desert is defined as a region without forests. According to geographers and climatologists desert has special definitions that change according to different conditions. There is no common and acceptable definition propounded so far in this field. The Desertification & Sand Dune Fixation Bureau (FRWO) with a view to its responsibility for the management and revival of deserted lands in the country and for the sustainable exploitation of desert resources has given a special definition which is as follows:
Desert is a piece of land located in arid, semi-arid and sub-humid arid regions without permanent natural cover or very little natural plant cover the exploitation of which is not cost –effective under natural circumstances.
On the whole, definitions used in the textbooks and technical reports of related international organizations can be summarized as follows:
Desert is a land with little precipitation, difficult environmental conditions, limited natural plant cover and high temperature differences in day and night, under wind erosion, high evaporation and transpiration, limitation of surface and under-ground water resources, unsuitable natural conditions for living and farming as well as its unique ecosystem and special flora and fauna .
Considering the global significance of the issue of desertification, the United Nations Convention to Combat Desertification (UNCCD) has defined desertification as follows :
Desertification means land degradation in arid, semi-arid and arid sub-humid areas resulting from various factors, including climatic variations and human activities .
According to the above mentioned definition, land degradation means the decline in biological productivity
.
Classification of Deserts
Deserts are divided into two groups based on their sources and formation processes as follows:
1- Natural or historical deserts
These types of desert are formed by geographical conditions such as location in a recognized altitude and longitude, having little precipitation, tense and long – term climatic changes, salt and gypsum layers as well as other geological events.
The main factors contributing to natural deserts in Iran are as follows:
1-The existence of the Alborz Mountains in the north and Zagros
Mountains in the west of country prevent the humid climate of the Mediterranean Sea and North Atlantic Ocean penetrate to the lowlands of Iran and thus adds to the decrease of precipitation in the central regions of the country creating a more severe climate . The location of Iran on the arid belt in the northern hemisphere, exacerbates the arid and hyper- arid climate in the central plateau which is characterized by little precipitation , high evaporation ( sometimes more than 4,000mm per year) and severe temperature fluctuations ranging between + 50 degrees in summers to - 20 centigrade in winters. Based on climatic classifications, more than 90 percent of the land area of Iran falls into the domain of arid, hyper arid and dry sub-humid climates and this has made the natural ecosystems more sensitive and fragile in these regions.
2- Human-induced deserts
Desertification due to human interference in nature is one of the general features of the decline in natural resources in I.R. of Iran. On the one hand, arid, semi-arid and arid sub-humid climatic conditions in vast areas of the country have made the ecosystems sensitive to destructive activities and interference. On the other hand, long term overexploitation intensifies this problem. Desertification, in the initial step, is characterized by the reduction or loss of biological productivity, but in its severe phase it is accompanied by the total deterioration of biological productivity, known as desertified land.
Iran has been, from beginning of history, the dwelling place of many tribes and communities and therefore exposed to exploitation. As long as the population growth matched the resources available in nature, the ecosystem was sustainable and in balance. However, population growth increased the need for food and fuel and consequently led to the overexploitation of natural resources. As a result, this destructive cycle resulted in land degradation in arid areas.