Flora of deserts and semi-deserts of Australia. Natural areas

And semi-deserts are specific natural areas, main distinctive feature which is drought, as well as poor flora and fauna. Such a zone can form in all climatic zones - the main factor is a critically low amount of precipitation. Deserts and semi-deserts are characterized by a climate with sharp daily temperature changes and a small amount precipitation: no more than 150 mm per year (in spring). The climate is hot and dry, evaporates before it can be absorbed into the water. Temperature changes are characteristic not only of the change of day and night. The winter and summer temperature difference is also very large. General background weather conditions can be defined as extremely severe.

Deserts and semi-deserts are waterless, dry areas of the planet where no more than 15 cm of precipitation falls per year. The most important factor their formation is the wind. However, it is not observed in all deserts hot weather, some of them, on the contrary, are considered the coldest regions of the Earth. Representatives of flora and fauna have adapted differently to harsh conditions these areas.

Sometimes the air in deserts in summer reaches 50 degrees in the shade, and in winter the thermometer drops to minus 30 degrees!

Such temperature changes cannot but affect the formation of the flora and fauna of the semi-deserts of Russia.

Deserts and semi-deserts are found in:

There are also special types of deserts - Arctic and Antarctic, the formation of which is associated with very low temperatures.

There are many reasons why deserts arise. For example, the Atacama Desert receives little rainfall because it is located at the foot of the mountains, which cover it from rain with their ridges.

Ice deserts formed for other reasons. In Antarctica and the Arctic, the bulk of the snow falls on the coast; snow practically does not reach the interior regions. Precipitation levels generally vary greatly; one snowfall, for example, can result in a year's worth of precipitation. Such snow deposits form over hundreds of years.

Natural area desert

Climate features, desert classification

This natural area occupies about 25% of the planet's land area. There are 51 deserts in total, 2 of which are icy. Almost all deserts were formed on ancient geological platforms.

General signs

The natural zone called “desert” is characterized by:

  • flat surface;
  • critical volume of precipitation(annual norm - from 50 to 200 mm);
  • rare and specific flora;
  • peculiar fauna.

Deserts are often found in the temperate zone Northern Hemisphere Earth, as well as tropical and subtropical. The relief of such an area is very heterogeneous: it combines highlands, island mountains, small hills and strata plains. Basically, these lands are drainless, but sometimes a river can flow through part of the territory (for example, the Nile, Syr Darya), and there are also drying lakes, the outlines of which are constantly changing.

Important! Almost all desert areas are surrounded by or near mountains.

Classification

There are different types of deserts:

  • Sandy. Such deserts are characterized by dunes and often arise sandstorms. The largest is the Sahara, characterized by loose, light soil that is easily blown by the winds.
  • Clayey. They have a smooth clay surface. They are found in Kazakhstan, the western part of Betpak-Dala, on the Ustyurt plateau.
  • Rocky. The surface is represented by stones and rubble, which form placers. For example, Sonora in North America.
  • Salt marshes. The soil is dominated by salts, and the surface often looks like a salt crust or quagmire. Distributed on the coast of the Caspian Sea, in Central Asia.
  • Arctic— located in the Arctic and Antarctica. They can be snowless or snowy.

Climatic conditions

The desert climate is warm and dry. Temperature depends on geographical location: maximum +58°C was recorded in the Sahara on September 13, 1922. Distinctive feature desert areas there is a sharp temperature drop of 30-40°C. During the day average temperature+45°C, at night - +2-5°C. In winter, the deserts in Russia can be frosty with light snow.

In desert lands it has low humidity. Strong winds with a speed of 15-20 m/s or more often occur here.

Important! The driest desert is the Atacama. There has been no rainfall on its territory for more than 400 years.


Semi-desert in Patagonia. Argentina

Flora

The desert flora is very sparse, consisting mainly of sparse shrubs that can extract moisture deep in the soil. These plants are specially adapted to live in hot and dry habitats. For example, a cactus has a thick waxy outer layer to keep water from evaporating. Sagebrush and desert grasses need very little water to survive. Desert and semi-desert plants have adapted to protect themselves from animals by growing sharp needles and thorns. Their leaves are replaced by scales and spines or covered with hairs that protect the plants from excessive evaporation. Almost all sand plants have long roots. In sandy deserts, in addition to herbaceous vegetation, there is also shrub vegetation: zhuzgun, sand acacia, teresken. Shrub plants are low and poorly leafy. Saxaul also grows in deserts: white on sandy soils, and black on saline soils.


Flora of desert and semi-desert

Most desert and semi-desert plants bloom in the spring, reproducing flowers until the hot summer begins. During wet winter and spring years, semi-desert and desert plants can produce a surprising amount of spring flowers. Pine trees, junipers and sage grow in desert canyons and on rocky mountains. They provide shelter from the scorching sun for many small animals.

The least known and underappreciated species of desert and semi-desert plants are lichens and cryptogamous plants. Cryptogamous or secretogamous plants - spore fungi, algae, pteridophytes, bryophytes. Cryptogamous plants and lichens need very little water to survive and thrive in dry, hot climates. These plants are important because they help stop erosion, which is very important for all other plants and animals because it helps keep the soil fertile during high winds and hurricanes. They also add nitrogen to the soil. Nitrogen - important nutrient for plants. Cryptogamous plants and lichens grow very slowly.

Annual ephemerals and perennial ephemeroids grow in clay deserts. In solonchaks there are halophytes or solyankas.

One of the most unusual plants that grow in this area is saxaul. It often moves from place to place under the influence of the wind.

Fauna

The fauna is also sparse - reptiles, spiders, reptiles or small steppe animals (hare, gerbil) can live here. Among the representatives of the order of mammals, the camel, antelope, wild ass, steppe sheep, and desert lynx live here.

To survive in the desert, animals have a specific sandy coloration, can run fast, dig holes and for a long time living without water is preferable night look life.

Among the birds you can find the raven, saxaul jay, and desert chicken.

Important! In sandy deserts there are sometimes oases - this is a place that is located above a cluster groundwater. There is always dense and abundant vegetation and ponds here.


Leopard in the Sahara desert

Characteristics of the climate, flora and fauna of the semi-desert

Semi-desert is a type of landscape that is intermediate option between desert and steppe. Most of them are located in the temperate and tropical zones.

General signs

This zone is distinguished by the fact that there is absolutely no forest on it, the flora is quite unique, as is the composition of the soil (very mineralized).

Important! Semi-deserts exist on all continents except Antarctica.

Climatic conditions

They are characterized by hot and long summer period with a temperature of approximately 25°C. Evaporation here is five times higher than precipitation levels. There are few rivers and they often dry up.

In the temperate zone they run in an unbroken line across Eurasia in an east-west direction. In the subtropical zone they are often found on the slopes of plateaus, highlands and plateaus (Armenian Highlands, Karoo). In the tropics it is very large areas(Sahel zone).


Fennec foxes in the desert of Arabia and North Africa

Flora

The flora of this natural zone is uneven and sparse. It is represented by xerophytic grasses, sunflowers and wormwood, and ephemerals grow. On the American continent, the most common are cacti and other succulents; in Australia and Africa, xerophytic shrubs and low-growing trees (baobab, acacia) are most common. Here the vegetation is often used to feed livestock.

In the desert-steppe zone, both steppe and desert plants are common. The vegetation cover mainly consists of fescue, wormwood, chamomile, and feather grass. Often wormwood occupies large areas, creating a dull, monotonous picture. In some places, kochia, ebelek, teresken, and quinoa grow among the wormwood. Where groundwater comes close to the surface, thickets of shin weed are found on saline soils.

The soil, as a rule, is poorly developed; its composition is dominated by water-soluble salts. Among the soil-forming rocks, ancient alluvial and loess-like deposits, which are reworked by winds, predominate. Gray-brown soil is typical for elevated flat areas. Deserts are also characterized by salt marshes, that is, soils that contain about 1% of easily soluble salts. In addition to semi-deserts, salt marshes are also found in steppes and deserts. Groundwater, which contains salts, upon reaching the soil surface is deposited into the soil. top layer, resulting in soil salinization.

Fauna

The fauna is quite diverse. To the greatest extent it is represented by reptiles and rodents. Mouflon, antelope, caracal, jackal, fox and other predators and ungulates also live here. Semi-deserts are home to many birds, spiders, fish and insects.

Protection of natural areas

Some desert areas are protected by law and are recognized as nature reserves and national parks. The list of them is quite long. From the deserts man guards:

  • Etosha;
  • Joshua Tree (in Death Valley).

Among semi-deserts the following are subject to protection:

  • Ustyurt Nature Reserve;
  • Tiger beam.

Important! The Red Book includes such desert inhabitants as the serval, mole rat, caracal, and saiga.


Chara desert. Transbaikal region

Economic activity

The climatic features of these zones are unfavorable for economic life, but throughout history entire civilizations developed in the desert zone, for example, Egypt.

Special conditions forced us to look for a way to graze livestock, grow crops and develop industry. Taking advantage of the available vegetation, sheep are usually grazed in such areas. They also breed in Russia Bactrian camels. Farming here is possible only with additional irrigation.

Development of technical progress and not limitless reserves natural resources, led to the fact that man reached the deserts. Scientific research showed that in many semi-deserts and deserts there are considerable reserves of natural resources, such as gas, precious. The need for them is constantly increasing. Therefore, equipped with heavy equipment and industrial tools, we are going to destroy previously miraculously untouched territories.

  1. The two largest deserts on planet Earth: Antarctica and the Sahara.
  2. The height of the highest dunes reaches 180 meters.
  3. The driest and hottest area in the world is Death Valley. But, nevertheless, more than 40 species of reptiles, animals and plants live in it.
  4. Approximately 46,000 square miles of arable land turns to desert each year. This process is called desertification. According to the UN, the problem threatens the lives of more than 1 billion people.
  5. When passing through the Sahara, people often see mirages. To protect travelers, a mirage map was compiled for caravan drivers.

Natural zones of deserts and semi-deserts are a huge variety of landscapes, climatic conditions, flora and fauna. Despite the harsh and cruel nature of the deserts, these regions have become home to many species of plants and animals.

Besides the most large deserts Australia - Victoria and the Great Sandy Desert, on the territory of the Green Continent there are also other dry areas.

If you are interested in the deserts of Australia, then you worth knowing that the mainland has both tropical and subtropical desert areas. What are these dry zones like?

The Gibson Desert is located in the center.

Europeans first visited this desert, covered with rubble unsuitable for agriculture. in 1874.

Despite the harsh climatic and natural conditions people live in this area - Australian Aboriginal tribe Pintubi.

This tribe of the indigenous people of the mainland is one of the topics that preserved the traditional ancient way of life of the aborigines Green Continent.

Also, the Gibson Desert rich in animal world . Typical representatives of Australia's animals live here - the red kangaroo, marsupial badger, moth lizard, grass wren and emu.

The marsupial badger also lives here, which previously inhabited 70% Australian territory, and today is on the verge of extinction. The main vegetation of the Gibson Desert is spinifex and acacia.

Simpson Desert

Simpson Desert, which is located in the heart of Australia is a protected area of ​​the Green Continent, where the world famous is located.

This body of water temporarily filled with water, fed by Australia's underwater rivers and home to many of Australia's animals.

They live here ducks, eagles, gulls, Australian pelicans, kingfishers, budgies, pink cockatoos, swallows and other representatives of the mainland’s avifauna.

Also found here marsupial jerboas, desert bandicoots, marsupial mice and moles, dingo dogs, wild camels and kangaroos.

The flora of the Simpson Desert consists of drought-resistant grasses and thorns. Today in the desert there are a number of protected areas. Tourists come here to take 4x4 rides through the dunes.

Interesting fact! In the 19th century, people wanted to graze cattle and build settlements here, but the climate did not allow this. The Simpson Desert has also been a disappointment to oil seekers who searched here in the 1970s and failed to find this natural resource.

Small Sandy Desert

Small sandy desert located in the west of the Green Continent. The flora and fauna, as well as the topography of this desert area, are similar to the characteristics of the Great Sandy Desert.

On the territory of the Small Sandy Desert there is its main watercourse - Savory Creek, which flows into Disappointment Lake located in the north of the desert.

Despite the rather harsh climate for which the deserts and semi-deserts of Australia are famous, tribes of the indigenous population of the mainland live here. The biggest one is Parnngurr tribe.

The only way through the desert, namely the Canning Cattle Route, runs in the northeast of the Little Sandy Desert.

Deserts of Australia - Tanami and Te Pinnacles

Another desert territory of Australia called Tanami, which is located in, has been explored more than other arid zones of the mainland. Europeans made expeditions here until 20th century.

The Tanami Desert is rocky sand dunes, the area of ​​which 292,194 km².

Climate Tanami – semi-desert. The average annual rainfall here is much higher than in other Australian deserts.

In 2007 The Northern Tanami Aboriginal Protected Area was created here, which covers an area of ​​approximately 4 million hectares. Today gold mining is carried out here. IN last years Various areas of tourism are developing.

It is important to know! The North Tanami Protected Area is home to Australian fauna and flora that are on the verge of extinction.

The desert called The Pinnacles is a small area located in the southwest of the Green Continent.

The title translates as "desert of pointed rocks" and speaks for itself. The sandy desert area is “decorated” with towering stones from one to five meters.

Find out more about the drylands of Australia, it becomes clear why some species of unique Australian animals could not survive in such harsh climatic conditions.

May 12, 2013

The presence of natural zones on the mainland and their location directly depend on climatic zones. Given that Australia is considered the driest continent, it becomes clear that there simply cannot be much diversity here. But the natural areas of Australia have an extremely unique flora and fauna.

Lots of deserts and few forests

On the smallest continent, zoning is clearly visible. This is due to the prevailing flat nature of the relief. Natural zones of Australia gradually replace each other in the meridional direction following changes in temperature and precipitation.

The Southern Tropic crosses the continent almost in the middle, and most of its territory is in hot tropical climatic zone, which makes the climate arid. In terms of annual precipitation, Australia ranks among all continents. last place. Most of its territory receives only 250 mm of precipitation throughout the year. In many areas of the continent, not a drop of rain falls for several years.

Australia, whose natural zones divide the continent into three parts, has several zones in the east and west, stretched along the coast, where the amount of precipitation is noticeably higher. The mainland is in first place in terms of the relative area of ​​desert areas and in last place in terms of forest area. In addition, only 2% of Australia's forestlands are of industrial importance.

Features of natural areas

Savannas and open forests are located in the subequatorial climate zone. The vegetation is dominated by grasses, among which grow acacias, eucalyptus trees, and bottle trees.

In the east of the continent, in conditions of sufficient moisture, there are such natural zones of Australia as tropical rainforests. Among palm trees, ficus and tree ferns live marsupial anteaters, wombats, kangaroos.

Australia's natural areas differ from similar areas on other continents. For example, semi-deserts and tropical deserts occupy huge areas on the mainland - almost 44% of its territory. In the Australian deserts you can find unusual thickets of dry thorny bushes called scrubs. Semi-desert areas overgrown with tough cereal plants and shrubs are used as pasture for sheep. There are also large sandy deserts, which differ from the deserts of other continents in that they do not have oases.

In the southeastern part and southwest of the continent there are subtropical forests, in which eucalyptus and evergreen beech grow.

The originality of the organic world

The flora of Australia, thanks to its long isolation from other continents, has big number endemic plants. Almost 75% of them can only be seen here and nowhere else. More than 600 species of eucalyptus, 490 species of acacia and 25 species of casaurines are found on the mainland.

The fauna is even more peculiar. Among animals, endemics account for almost 90%. Only in Australia can you find mammals that disappeared on other continents a long time ago, for example, the echidna and the platypus - ancient primitive animals.

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The most arid central regions of the continent occupy the largest areas of Australia. There are a variety of terrain types here, from shifting sands, salt marshes, gravelly rocky areas to thorny forests. However, two groups dominate: 1) acacia formation Mulga-scrub; 2) formation dominated by spinifex grass, or triodni. The latter dominates the most deserted central regions.

Acacia shrub and low-growing (3-5 m) tree-shrub deserts and semi-deserts are similar in nature to the dry thorny woodlands of Somalia or the Kalahari on the African continent. The northern variants of these groups, with a short summer wet period and an abundance of tall termite mounds, can also be considered as an extreme arid variant of the savannah and woodland zone. The dominant plant almost everywhere is ours - veinless acacia - and other phyllodes species. The number of eucalyptus and casuarina trees is small; they are confined to dry river beds and extensive depressions with close occurrence groundwater. The grass cover is often almost absent or represented by very sparse groups of grasses, saltworts and other leafy succulents.

The sandy areas in the center and west of the continent are covered with thickets of extremely xeromorphic hard grasses of the genus Triodia. In Queensland and New South Wales, a prickly pear cactus has proliferated and become a nasty weed. Prickly pear was brought from South America in the 80s of the last century and settled over an area of ​​about 24 million hectares.

Unlike the Sahara and Namib, the deserts of Australia do not have significant areas of “absolute” deserts, practically free from higher plants. In drainless basins and along the shores of salt lakes, halophytic formations formed special types widespread ancient genera (solyanka, quinoa, parfolia, prutnyak, saltpeter). Schober's saltpeter also grows in the semi-deserts of Eurasia. The Nullarbor Plain adjacent to the Great Australian Bight has semi-desert vegetation that already develops in a subtropical, close to temperate, climate. It is dominated by tall (up to 1.5 m) bushes of various halophytes - representatives of the goosefoot (hodgepodge, quinoa, etc.), which are considered a good forage plant for sheep. On the plain, due to the widespread occurrence of karst phenomena, there are almost no surface water bodies.

Some botanists believe that true deserts are almost never found in Australia, and semi-deserts predominate. Indeed, the density of vegetation cover in arid regions of the continent is usually relatively large, which is associated with regular short wet season. The annual amount of precipitation is never below 100 mm, but usually it is close to 200-300 mm. In addition, in many places there is a shallow aquifer, where moisture is retained for a long time and is available to plant roots.

Animal world. In the faunal aspect, the animal world of arid internal regions Australia as a whole is a depleted version of dry savannah and open forest groups. Most species are found in both deserts and savannas, although a number of groups of animals are especially numerous in desert and semi-desert habitats. Among mammals, such typical animals include the marsupial mole, marsupial jerboa, comb-tailed marsupial mouse and comb-tailed marsupial rat. The entire central and western parts of the continent are inhabited by large red kangaroos. These animals are numerous in many places and are considered undesirable competitors for sheep. The same applies to smaller wallaby species. Of the smallest species of the kangaroo family (smaller than a rabbit), kangaroo rats are interesting for their ability to carry a “load” - an armful of grass, grasping it with their long tail. Many species of kangaroo rats widely inhabited almost the entire continent, but are now severely exterminated by introduced dogs and foxes, and are also replaced by rabbits, which colonize and destroy their original habitats. Therefore, now they are better preserved in desert areas, where the influence of introduced animals is less felt. The most common dog here is the dingo. In some areas, wild animals have multiplied dromedary camels, brought to the mainland in the last century as vehicle on expeditions.

The most famous bird of the semi-desert regions of the mainland is the emu. This is the only species (sometimes two closely related species are distinguished) of a special family related to cassowaries. Weaverbirds and small parrots feeding on cereal seeds (including triodia) are common throughout arid regions. This is already mentioned zebra finch, budgies, as well as nymph parrots. All these species nest in hollows of dry trees. The night parrot is very typical for arid regions. This is truly a nocturnal bird. She spends most of her time on the ground; her diet is based on triodia seeds. Unlike most other parrots, the night parrot makes its nest not in hollows, but among thickets of thorny grasses.

Of the vertebrate animals, various reptiles are especially characteristic of deserts and semi-deserts, of which lizards of the agamidae, skink and monitor lizard families predominate. The Lepidopus family, characteristic of Australia, which includes snake-like lizards with reduced limbs, also has desert representatives. Among the agamidae in the tropical northern regions of dry woodlands and semi-deserts there are frilled lizards, characteristic of the savannah. Species of this genus have the ability to run on two hind limbs. This method of movement was characteristic of some Mesozoic dinosaurs. Several species of bearded lizards, similar to our common agamas, live in deserts. The most original appearance of Moloch. This small, up to 20 cm, flat lizard is all covered with outgrowths and spines. Moloch's skin can absorb moisture. In its lifestyle and appearance it resembles the American desert toad-like lizards. Moloch's main source of nutrition is ants.

Skinks are mainly endemic to Australia (sometimes including New Zealand) genera, species of which live both in deserts and in other zones. There are especially many species of the endemic genus Ctenotus - small graceful lizards with smooth scales.



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