Desert: environmental problems, desert life

Deserts are dry spaces with hightemperature and low humidity. Researchers consider such places on the ground territories of geographical paradoxes. Geographers and biologists assert that the deserts themselves are the main ecological problem of the Earth, or rather desertification. This is the name of the process of loss of a constant vegetation by a natural complex, the impossibility of a natural restoration without human participation. We will find out what territory the desert is on the map. The ecological problems of this natural zone will be established in direct connection with human activities.

Country of geographic paradoxes

Most arid areas of the globeis in the tropical belt, they receive from 0 to 250 mm of rain per year. Evaporation is usually ten times greater than the amount of precipitation. Most often the drops do not reach the surface of the earth, evaporate even in the air. In the stony Gobi Desert and in Central Asia in winter, temperatures fall below 0 ° C. Significant amplitude is a characteristic feature of desert climate. For a day it can be 25-30 ° C, in the Sahara reaches 40-45 ° C. Other geographic paradoxes of the deserts of the Earth:

• sediments that do not wet the soil;
• dust storms and vortexes without rain;
• drainless lakes with a high salt content;
• sources that are lost in the sands, not giving rise to streams;
• rivers without a mouth, waterless channels and dry accumulation in deltas;
• wandering lakes with constantly changing outlines of the shores;
• trees, shrubs and herbs without leaves, but with spines.

The largest deserts of the world

Vast territories, devoid of vegetation,are attributed to the drainless regions of the planet. Here, trees, shrubs and grass without leaves predominate, or there is no vegetation, which is reflected in the term "desert" itself. The photos posted in the article give an idea of ​​the harsh conditions of dry territories. The map shows that the deserts are located in the Northern and Southern hemispheres in a hot climate. Only in Central Asia, this natural zone is in the temperate zone, reaching 50 ° N. w. The largest deserts of the world:

• Sahara, Libyan, Kalahari and Namib in Africa;
• Monte, Patagonia and Atacama in South America;
• Great Sand and Victoria in Australia;
• Arabian, Gobi, Syrian, Rub-el-Khali, Karakum, Kyzylkum in Eurasia.

Such zones as the semi-desert and desert on the world map occupy as a whole from 17 to 25% of the entire land of the globe, and in Africa and Australia - 40% of the area.

Drought on the seacoast

Unusual location is typical for Atacama andNamiba. These lifeless arid landscapes are on the ocean! The Atacama Desert is located in the west of South America, surrounded by rocky peaks of the Andean mountain system, reaching a height of more than 6,500 m. In the west, the territory is washed by the Pacific Ocean with its cold Peruvian current.

Atacama is the most lifeless desert, hereRecorded a record low rainfall of 0 mm. Small rains happen once in several years, but in winter fogs from the ocean coast often come. About 1 million people live in this arid region. The population is engaged in animal husbandry: surrounded by pastures and meadows all the high desert. The photo in the article gives an idea of ​​the harsh landscapes of Atacama.

Types of deserts (ecological classification)

1. Arid - zonal type, characteristic of the tropical and subtropical belts. The climate in this area is dry and hot.
2. Anthropogenic - arises from director indirect influence of man on nature. There is a theory explaining that this is a desert whose ecological problems are associated with its expansion. And all this is caused by the activities of the population.
3. The inhabited is a territory on which there are permanent residents. There are transit rivers, oases, which are formed in places of groundwater outlet.
4. Industrial - the area with extremely poor vegetation and wildlife, which is due to production activities and environmental disturbance.
5. Arctic - snow and ice expanses in high latitudes.

Environmental problems of deserts and semi-desertsnorth and in the tropics are similar in many respects: for example, there is insufficient precipitation, which is a limiting factor for plant life. But for the icy expanses of the Arctic are characterized by extremely low temperatures.

Desertification - loss of continuous vegetation cover

Approximately 150 years ago, scientists noted an increaseSahara. Archaeological excavations and paleontological studies have shown that not always in this territory was only the desert. Environmental problems were then the so-called "drying up" of the Sahara. So, in the XI century, farming in North Africa could be practiced up to 21 ° latitude. For seven centuries the northern boundary of agriculture moved to the south to the 17th parallel, by the 21st century it moved even farther. Why does desertification occur? Some researchers explained this process in Africa by "shrinking" the climate, others cited data on the movement of sands that fall asleep oases. Sensation was the work of Stebbinga "The Desert Created by Man", which was published in 1938. The author cited data on the progress of the Sahara to the south and explained the phenomenon by the improper conduct of agriculture, in particular trampling of cereal vegetation, irrational farming systems.

Anthropogenic cause of desertification

As a result of studies of the movement of sand inSahara scientists found that during the First World War, the area of ​​agricultural land and the number of cattle decreased. Woody-shrubby vegetation then reappeared, that is, the desert receded! Environmental problems are now exacerbated by the almost total absence of such cases when territories are withdrawn from agricultural traffic for their natural recovery. Reclamation and reclamation are carried out on a small area.

Desertification is most often led by activitieshuman, the cause of "drying out" is not climatic, but anthropogenic, associated with excessive exploitation of pastures, excessive development of road construction, irrational farming. Desertification under the influence of natural factors can occur on the border of already existing drylands, but less often than under the influence of human activities. The main causes of anthropogenic desertification are:

• mining of minerals in open pit (in quarries);
• grazing without restoration of pasture productivity;
• deforestation of forests planting soils;
• Irregular irrigation systems (irrigation);
• strengthening of water and wind erosion:
• drainage of reservoirs, as in the case of the disappearance of the Aral Sea in Central Asia.

Environmental problems of deserts and semi-deserts (list)

1. Lack of water is the main factor that increases the vulnerability of desert landscapes. Strong evaporation and dust storms lead to erosion and further degradation of infertile soils.
2. Salinization - an increase in the content of readily soluble salts, the formation of solonetzes and solonchaks, practically unsuitable for plants.
3. Dusty and sandstorms - air movements,lifting a significant amount of fine detrital material from the surface of the earth. In solonchaks, the wind carries salt. If sands and clays are enriched with iron compounds, then yellow-brown and red dust storms appear. They can cover hundreds or thousands of square kilometers.
4. "Devils of the Desert" - dusty sand vortexes,lifting into the air a huge amount of fine detrital material to a height of several tens of meters. Sand pillars have an expansion at the top. They differ from tornadoes by the absence of cumulus clouds carrying rain.
5. Dusty bowls are territories where catastrophic erosion occurs as a result of drought and uncontrolled plowing of the land.
6. Clogging, accumulation of waste - extraneous for the natural environment of objects that for a long time do not decompose or release toxic substances.
7. Exploitation and contamination by man in the mining of minerals, the development of livestock, transport and tourism.
8. Reduction of the area occupied by plants of desert, impoverishment of fauna. Loss of biodiversity.

The life of the desert. Plants and Animals

Severe conditions, limited water resources andThe barren landscapes of the deserts change after the rains pass. Many succulents, such as cacti and fatty, are able to absorb and store bound water in stems and leaves. Other xeromorphic plants, such as saxaul and wormwood, develop long roots reaching the aquifer. Animals have adapted to get the moisture they need from food. Many fauna representatives switched to nightlife to avoid overheating.

The surrounding world, the desert in particular, is experiencingnegative impact of the population. There is a destruction of the natural environment, as a result, man himself can not enjoy the gifts of nature. When animals and plants lose their habitual habitat, this also negatively affects the life of the population.