desert - dry space with high temperature performance and low humidity.Researchers believe such places on earth geographic territories paradoxes.Geographers and biologists say that the desert themselves - this is the main environmental problem of the earth, or rather desertification.So we call the loss of natural complex of permanent vegetation, the inability of natural recovery without human intervention.Find out which area on the map is desert.Environmental problems of the natural area will set in direct relation to human activities.
country geographic paradoxes
Most drylands of the world is in the tropics, they get from 0 to 250 mm of rain per year.Evaporation typically ten times higher than the amount of precipitation.In most cases, droplets do not reach the earth's surface evaporates in the air.In stony Gobi desert and Central Asia in the winter temperature drops below 0 ° C.A large amplitude - characteristic desert climate.During the day it can be 25-30 ° C in the Sahara reaches 40-45 ° C..Other geographical deserts of the paradoxes of the Earth:
- rainfall without wetting the soil;
- dust storms and eddies without rain;
- inland lakes with high salt content;
- sources that are lost in the sands without giving rise to streams;
- river without mouth, waterless riverbed and dry storage in the delta;
- wandering lake with ever-changing contours of the coast;
- trees, shrubs and herbs with no leaves but thorns.
largest desert in the world
Large areas devoid of vegetation, referred to the inland areas of the planet.It is dominated by trees, shrubs and herbs with no leaves or no vegetation, reflecting the term "desert".Photos featured in the article, give an idea of the harsh conditions of dry areas.On the map you can see that the deserts are located in Northern and Southern Hemispheres in hot climates.Only in Central Asia, this natural area is located in the temperate zone, up to 50 ° C.w.The largest desert in the world:
- Sahara, Libyan, Kalahari and Namib in Africa;
- Monte, Patagonian and Atacama in South America;
- Great Sandy and Victoria in Australia;
- Arabian, Gobi, Syrian, Rub Al Khali desert, the Karakum, Kyzylkum in Eurasia.
Such areas as semi-desert and desert on the world map as a whole take from 17 to 25% of the total land area of the world, and in Africa and Australia - 40% of the area.
Drought seaside
unusual arrangement is typical of the Atacama Desert and Namibia.These lifeless arid landscapes are on the beach!The Atacama Desert is located in the west of South America, surrounded by rocky peaks of the Andes mountain range, which reaches a height of over 6,500 m. In the west, the territory is washed by the Pacific Ocean with its cold Peruvian current.
Atacama - the lifeless desert, here marked a record low rainfall - 0 mm.Light rain happens once every few years, but in the winter often looming mists from the coast of the ocean.In this arid region is home to about 1 million people.The population is engaged in animal husbandry: surrounded by pastures and meadows, all the high desert.Photos in the article gives an idea of the harsh landscapes of the Atacama.
Types deserts (ecological classification)
- Arid - zone type, characteristic of tropical and subtropical zones.The climate in the area is hot and dry.
- anthropogenic - is the result of a direct or indirect impact of man on nature.There is a theory that explains that this desert, where environmental problems related to its expansion.And all this is due to the activities of the population.
- arrival - territory in which there are permanent residents.There transit rivers, oases, which are formed in places where the groundwater.
- industry - areas with extremely poor vegetation cover and wildlife due to industrial activity and a violation of the natural environment.
- Arctic - snowy and icy expanses of the high latitudes.
Ecological problems of deserts and semi-deserts in the north and in the tropics are very similar: for example, there is a lack of rainfall, which is a limiting factor for plant life.But the icy expanse of the Arctic are characterized by extremely low temperatures.
Desertification - the loss of solid vegetation
About 150 years ago, scientists have noted an increase in the area of the Sahara.Archaeological excavations and paleontological studies have shown that is not always in this area there was only desert.Environmental problems, then, is the so-called "shrinking" of the Sahara.Thus, in the XI century, agriculture in North Africa could engage up to 21 ° latitude.For seven centuries, the northern border of agriculture has moved south to the 17th parallel, to the XXI century has shifted even further.Why is desertification?Some researchers explain the process in Africa "desiccation" climate led other data on the movement of sand, covered oases.The sensation was the work of Stebbing "Desert, created by man", released in 1938.The author gives details of the progress of the Sahara to the south and explained the phenomenon of improper farming, particularly livestock trampling grassy vegetation, unsustainable farming systems.
man-made causes of desertification
The studies movement of sand in the Sahara, scientists have found that during the First World War, the area of agricultural land and livestock of cattle decreased.Trees and shrubs then reappeared, that is retreating desert!Environmental problems are now compounded by the almost complete lack of cases in which the territory shall be withdrawn from agricultural use for their natural regeneration.Conducted reclamation and remediation activities at the small square.
desertification often leads human activity the cause of "shrinkage" is not the climate and anthropogenic associated with immoderate exploitation of pastures, excessive development of road construction and unsustainable agriculture.Desertification under the influence of natural factors may occur at the boundary of the existing dry areas, but less than under the influence of human activities.The main causes of anthropogenic desertification:
- mining open pit (quarry);
- grazing without restoring the productivity of pastures;
- felling of forest plantations, soil reinforcement;
- incorrect irrigation (irrigation);
- increased water and wind erosion:
- draining reservoirs, as is the case with the disappearance of the Aral Sea in Central Asia.
Ecological problems of deserts and semi-deserts (list)
- Lack of water - the main factor that increases the vulnerability of desert landscapes.Strong evaporation and dust storms lead to erosion and further degradation of marginal soils.
- Salinity - increased content of soluble salts, the formation of solonetz and salt marshes, is almost unusable for plants.
- Dust and sandstorms - the movement of air rises from the earth's surface a significant amount of small debris.On the salt marsh wind carries salt.If sand and clay enriched with iron compounds, then there are yellow-brown and red dust storms.They can cover hundreds or thousands of square kilometers.
- «Devils Desert" - dusty sand whirls, rises into the air a huge amount of small debris to a height of several tens of meters.Sandy poles are at the top of the extension.Different from tornadoes absence of cumulus clouds carrying rain.
- Dusty bowls - territory where there is a catastrophic erosion as a result of drought and uncontrolled plowing up the ground.
- clogged, accumulation of waste - environment for foreign objects that for a long time do not decompose or release toxic substances.
- Operation and human pollution in mining, livestock development, transport and tourism.
- reduction of the area occupied by plants of the desert, the impoverishment of fauna.The loss of biodiversity.
Living Desert.Plants and animals
harsh conditions, limited water resources and the barren desert landscape changed after the rains.Many succulents such as cacti and Jade, are able to absorb and store bound water in the stems and leaves.Other xeromorphic plants such as saxaul and Artemisia, develop long roots that reach the aquifer.Animals adapted to receive the moisture they need from food.Many fauna switched to nocturnal to avoid overheating.
world around us, the desert in particular, is experiencing the negative impact of the activities of the population.There is destruction of the environment as a result of the man himself can not enjoy the gifts of nature.When animals and plants lose their usual habitat, it also negatively affects the life of the population.
