Vegetation and animals of the savannah. Savannah natural area

The article gives a definition of what savanna is. The climatic features of the natural zone are described, the characteristics of soils, flora and fauna are given.

This information will be useful for schoolchildren and students in preparation for a lesson, report or exam.

What are savannahs

Savannas are vast territories that occupy a significant part of the subequatorial belt, covered with tall herbaceous vegetation and rare trees.

From the description of the natural zone of savannas and woodlands, the main points should be noted:

1. The grass cover is higher than in the steppes, and it is based on stiff-leaved grasses.
2. The vegetation density is high and low so that the soil is visible.
3. There may be no trees at all, but there are areas that are almost sparse forest.

Geographical position

Location - subequatorial belt both in the north and in southern hemisphere... The map of natural zones shows that herbaceous areas cover almost 40% of the area of ​​Africa, and some areas are located in Australia, Northeast Asia, America.

V South America the natural area covers the Brazilian Highlands and the Orinoco River plains. In Brazil, the areas are occupied mainly by open woodland; in the Orinoco basin, there is almost no woody vegetation. South American savannahs wear different names: Brazilian - Campos, Venezuelan - Llanos.

In Asia, the natural zone occupies parts of India, Burma, Ceylon, Indochina.

In Australia, grassy areas are located in the northeast, characterized by a pronounced dry period.

Savannah plants

The flora is represented by a high grass cover with freestanding trees and shrubs, small groups of trees.

Elephant grass

Most of the plants are hydrophytes; there are also xerophytes adapted to the dry season. In dry months, grains burn out and many trees lose their foliage. Grasses stretch up to 3 m, and in lowlands up to 5 m.

Typical plant species:

• elephant grass;
• oil palm;
• doom palm;
• pandanus;
• the baobab is a thick tree with an oddly shaped trunk.

In more humid places, the cereal cover becomes lower (up to 1.5 m), supplemented by acacias - trees with a dense spreading crown resembling an umbrella.

More arid areas are characterized by thorny semi-savannahs. Trees almost all year without leaves, the grass carpet is sparse, low (up to 1 m).

The flora is represented by low thorny tree species, succulents, cushion shrubs. Some scientists call these areas the African steppe.

Soil

The main ones are red-brown and lateritic soils, characterized by a sufficient humus content, due to the abundant decomposition of the grass.

Due to periodic moisture in the soil layers, saturation with metal oxides is active, therefore, crusts often appear on the surface of the earth.

The seasonality of moistening affects the processes of soil formation. In the wet season, the soil layers are intensively leached, in the dry season, due to the heating of the earth's surface, the soil solutions rise. Therefore, the accumulation of humus, soil blackening, the formation of chernozems is typical for dry savannas, where the period without precipitation is long.

Relief

On the African continent, the zone of savannas and woodlands occupies the plateau of East Africa, the watershed plateaus of the Zambezi, Congo, Limpopo rivers, and some areas of the high Kalahari plains.

Savannah in Tanzania

In South America, savannas are found on the Brazilian and Guiana Highlands, the Gran Chaco Plain, in the Orinoco Basin.

In Australia - in the northeastern plains.

Climate and climatic zones

Savannahs are located in the subequatorial climatic zone... Two seasons are clearly identified: winter dry and summer wet. Annual temperatures range from 18 to 32 ° C. Temperature fluctuations are slow, not expressed.

The dry cool period lasts from November to April. The average temperature is 21 ° C. The weather is sunny, fires are frequent. No more than 4 inches (100 mm) of precipitation falls.

The dry season is the time of migrations. Huge herds of ungulates go in search of food and water, predators rush after them. Woody species survive in dry times thanks to their deep root system and dense, refractory bark.

The hot humid period begins in May and lasts until October. Rainfall over the period reaches 10 to 30 inches (250 to 750 mm). Heavy rain falls in the afternoon.

In the rainy season, savannah life is in full swing, the land is reborn after a drought, covered with a lush green carpet.

Savannah dwellers

The fauna of the savannah is unique. Nowhere else on the planet is there such a variety of large ungulates and predatory animals.

Unfortunately, since the beginning of the 20th century wild nature Seriously suffers because of the activities of poachers and irrepressible hunters, road construction, allocation of significant territories for cattle breeding and agriculture.

Horse antelope

The list of animals that have disappeared due to hunting activities includes:

• white-tailed wildebeest;
• horse antelope;
• zebra quagga.

Ungulates

The largest group of bush ungulates lives in Africa.

The most common are:

• blue wildebeest;
• zebras;
• Thompson's gazelles;
• Grant's gazelles;
• impala;
• Cannes;
• cow antelopes;
• swamp;
• giraffes;
• buffalo;
• warthogs;
• African elephants.

Kudu antelope

Rare ungulates, found only in reserves, are kudu, oryx.

Black and white rhinos are on the verge of extinction. Their luxurious horn, as can be seen in the photo, is a valuable prey for poachers.

Great efforts are being made in the reserves to preserve these animals.

Predators

Predatory animals are as diverse as herbivores.

African leopards

On the African plains, the following are common:

• lions;
• spotted hyenas;
• hyena dogs;
• leopards;
• cheetahs;
• caracals;
• Nile crocodiles.

The American steppes are inhabited by:

• jaguars;
• ocelots;
• maned wolves;
• cougars.

Dingo dog

In Australia:

• monitor lizards;
• Dingo dogs.

Birds

The variety of African birds amazes and attracts tourists from all over the world.

African ostrich

Baboons and numerous species of monkeys coexist with birds in the trees. Flamingos are the adornment of ponds.

Nandu ostriches are inhabitants of the Brazilian steppes, emu ostriches are Australian.

Insects

Among the insects that eat the green parts of plants, it can be noted:

• locusts (the most common family);
• bronzes;
• cicadas;
• crunchy;
• caterpillars;
• leaf beetles;
• goldfish;
• stick insects.

Of the processors of dead organic matter, the following are common:

• termites (savannas have the largest number of termite mounds, often of enormous size);
• crickets;
• worms;
• cockroaches;
• centipedes;
• darkling beetles;
• terrestrial molluscs.

Termites are the main food source for Australian and South American anteaters.

Every year more and more deserts come on the savannahs. This is especially noticeable in Africa. The main reason why savannahs give way to deserts is human activity. A person for his needs takes too much water from reservoirs, which is why the vegetation experiences a severe moisture deficit.

Another reason for desertification is global warming and intensive livestock raising. Grazing cattle eats grass so actively that the grass cover does not have time to recover.

Savannah(aka campos or llanos) - steppe-like places characteristic of more elevated tropical countries with a dry continental climate. Unlike the real steppes (as well as the North American prairies), the savannah, in addition to grasses, also contains shrubs and trees, sometimes growing as a whole forest, as, for example, in the so-called "campos cerrados" of Brazil. The herbaceous vegetation of the savannah consists mainly of tall (up to ⅓-1 meter) dry and hard-skinned grasses, usually growing in turf; tussocks of other perennial grasses and shrubs are mixed with cereals, and in damp places flooded in spring, also various representatives of the sedge family. Shrubs grow in savannas, sometimes in large thickets, covering an area of ​​many square meters. Savannah trees are usually undersized; the tallest of them are not taller than our fruit trees, to which they are very similar in their crooked stems and branches. Trees and shrubs are sometimes braided with lianas and overgrown with epiphytes. Bulbous, tuberous and fleshy plants in savannas, especially in the flaming continent, are few. Lichens, mosses and algae are extremely rare in savannas, only along rocks and trees.

General characteristics of savannas

The general appearance of savannas is different, which depends, on the one hand, on the height of the vegetation cover, and on the other hand, on the relative amount of grasses, other perennial grasses, semi-shrubs, shrubs and trees; for example, the Brazilian shrouds ("campos cerrados") are actually light, sparse forests, where you can walk and drive freely in any direction; the soil in such forests is covered with a vegetative herbaceous (and semi-shrub) cover ½ or even 1 meter high. In the savannas of other countries, trees do not grow at all or are extremely rare and are very short. The grass cover is also sometimes very low, even pressed to the ground. A special form of savannah is the so-called llanos of the Republic of Venezuela, where trees are either completely absent, or are found in a limited number, with the exception of only damp places where palm trees (Mauritia flexuosa, Corypha inermis) and other plants form whole forests (however, these forests do not belong to the savannas); in llanos there are sometimes single specimens of Rhopala (trees from the Proteaceae family) and other trees; sometimes the cereals in them form a cover in the height of a person; Compositae, legumes, labiates, etc. grow between grasses. In the rainy season, many llanos are flooded by the floods of the Orinoco River.

The vegetation of the savannas is generally adapted to the dry continental climate and to the periodic droughts that occur in many savannas for months. Cereals and other grasses rarely form creeping shoots, but usually grow in turf. The leaves of cereals are narrow, dry, tough, hairy, or covered with a waxy coating. In cereals and sedges, young leaves remain rolled up into a tube. In trees, the leaves are small, hairy, shiny ("varnished") or covered with a waxy bloom. The vegetation of the savannah generally has a pronounced xerophytic character. Many species contain large amounts of essential oils, especially the species of the vervain, labiate and myrtle families of the blazing continent. The growth of some perennial grasses, semi-shrubs (and shrubs) is especially peculiar, namely, the fact that the bulk of them, which is in the ground (probably the stem and roots), grows strongly into an irregular tuberous ligneous body, from which then numerous, mostly unbranched or weakly branched offspring. In the dry season, savannah vegetation freezes; Savannahs turn yellow, and dried plants are often exposed to fires, due to which the bark of trees is usually scorched. With the onset of rains, savannahs come to life, covered with fresh greenery and dotted with numerous different flowers.

Savannahs are characteristic of the flaming continent itself, but in other countries many places can be indicated that are very similar in nature to their vegetation to savannahs. These are, for example, the so-called Campine in the Congo (in Africa); in South Africa, some places are covered with vegetation, consisting mainly of grasses (Danthonia, Panicum, Eragrostis), of other perennial grasses, dwarf shrubs and trees (Acacia horrida), so that such places resemble the prairies of North America and the savannahs of a burning continent; similar places are found in Angola.

The eucalyptus forests of Australia are quite similar to the "campos cerratos" of the Brazilians; they are also light and so rare (the trees are far apart from one another and do not close with crowns) that it is easy to walk in them and even drive in any direction; the soil in such forests in the rainy season is covered with green thickets, consisting mainly of cereals; in the dry season, the soil is exposed.

In areas located a few degrees north and south of the equator, the climate is usually very dry. However, in certain months it gets very hot and it rains. Such places located all over the world are called savanna zones. This name comes from the African savannah, which is the most extensive region with this type of climate. When the rain comes The savannah zones are located between two tropics - lines where twice a year the sun at noon is exactly at its zenith. At a time like this, it gets much hotter there and much more evaporates from this. sea ​​water, that leads to heavy rains... In the areas of savannahs, located closest to the equator, the sun is exactly at its zenith in the intermediate moments of the year (in March and September), so that one rainy season is separated by several months. In the savannah regions farthest from the equator, both rainy seasons are so close in time to each other that they practically merge into one. The rainy season lasts from eight to nine months, and at the equatorial borders - from two to three. What grows in the savannah? Living conditions in the savannah are very harsh. The soil contains little nutrients, during dry seasons it dries up, and during wet seasons it becomes waterlogged. In addition, there are frequent fires at the end of dry seasons. Plants that have adapted to savannah conditions are very fierce.

There are thousands of different herbs growing there. Trees, on the other hand, need some specific qualities to protect them from drought and fire in order to survive. For example, the baobab is distinguished by a thick, fire-protected trunk, capable of storing water reserves, like a sponge. Its long roots suck in moisture deep underground. Acacia has a wide, flat crown that creates shade for the leaves growing below, thereby preventing them from drying out.

Savannah Wildlife Many areas of the savannah are now used for herding and wild life has completely disappeared. However, in the African savannah there are huge National parks where wild animals still live. Savannah animals were forced to adapt to survive in drought conditions. Large herbivores such as giraffes, zebras, wildebeests, elephants and rhinos are capable of trekking great distances and, if it gets too dry in some place, they go where it rains and where there is a lot of vegetation. Predators such as lions, cheetahs and hyenas hunted the wandering herds of animals. Small animals find it difficult to go in search of water, so they prefer to hibernate during the dry season. This is called summer hibernation.

These are flat or slightly hilly plains, where open, grassy areas alternate with groups of trees or dense thickets of thorny bushes. In the rainy season, the savannah is covered with tall grass, which turns yellow and burns out with the onset of the dry season. Agriculture in the savannah area is almost undeveloped, and the main occupation of the local population is cattle breeding.

Soils and vegetation

In savannas, soils are developed, united under the name of red-brown; when distinguishing them into a special type, they use geographical features, that is, they include open areas with a grassy cover. They are characterized by more or less humus content from decomposition of herbaceous vegetation, as a result of which such soils are rich in nutrients. In soils of periodic moistening, in savannas, the processes of enrichment with sesquioxides occur more vigorously than in the red soils of humid tropical forests, and often lead to the formation of a dam, that is, a hard crust on the surface, or the fertile granular structure of the soil mentioned above.

In savannas, the sharp seasonality of precipitation is reflected in the processes of soil formation: during the rainy period, there is a rapid and vigorous leaching of soils, while in the dry period, due to the strong heating of the surface layers, the opposite process occurs - the rise of soil solutions. Therefore, humus accumulates to a greater extent in dry savannas and steppes with a long rainless period. Savannah soils, depending on the amount of precipitation and the duration of the dry period, represent a great variety, forming transitions from lateritic and red-brown soils of cereal savannas to black and chernozem dry savannas. Depending on the combination of climatic and soil conditions, as well as on the relief, savannas are distinguished by a large variety of plant communities and the general nature of the aspect.

The main processes of soil formation

Soils develop on ancient continental flattening surfaces in two-season climate zones with an annual rainfall of 400-500 mm. In terms of humidity, the climate is arid, with an average annual temperature of + 19 °, + 22 °, an average temperature in January + 24 °, + 27 °, and in July + 14 °, + 17 °.

The soils are red-brown subarid with calcareous nodules on ancient crust and brown tropical subarid. They are distributed mainly in the East African Plateau, the Ethiopian Highlands, in the Kalahari Basin, as well as in the Sahel zone (on the border with the Sahara). The soils develop in the arid conditions of the tropics with a dry season of 4-6 months, with an annual rainfall of 200 to 500 mm, and in the Guinea part - up to 700 mm. The average annual temperature reaches + 26 °, + 28 °. Absolute heights within the plateau 300-500 m, and on the plateaus 1000-1500 m.

Brown tropical subarid soils were described most clearly and genetically by R. Maenien. He established the specificity of brown subarid soils, which are formed in a two-season climate, when short-term but massive rains fall within three months. In the dry and hot season, the temperature reaches + 45 ° C. The average annual temperature in this zone is + 27 °, + 28 °, the amount of precipitation is 200-350 mm.

Black tropical soils are formed at an average annual temperature of + 25 °, + 28 ° and the amount of annual precipitation from 200 to 1000 mm. A sharp alternation of wet and dry seasons is characteristic.

general characteristics

Remark 1

Savannahs are territories, the main vegetation of which is forbs and occasionally scattered shrubs and trees. In savannah dry and rainy seasons are sharply distinguished.

Savannahs belong to the climatic regions located in the subequatorial and tropical zones, which are characterized by a dry continental climate, some areas with a dry Mediterranean climate.

Savannahs are common on all continents except Antarctica.

Savannahs have a lot in common with steppes temperate latitudes- according to the mode of humidification and habitat conditions (high air temperature and low precipitation).

Herbaceous vegetation consists mainly of tall, hard-skinned grasses, many perennial grasses and shrubs. In damp places, various representatives of the sedge family are found. Semi-shrubs and shrubs grow in large thickets and occupy significant areas. The trees are undersized with crooked trunks and branches. Shrubs and trees are often overgrown with epiphytes and entwined with vines.

Sometimes the savanna looks like a rare light forest (Brazil). The soil in the forests is covered up to one meter in height with herbaceous and semi-shrub cover. In the savannas of other countries, trees are extremely rare and stunted. The grassy cover in such savannas is often pinned to the ground.

Climatic features

Savannah is characterized by monsoon-trade wind circulation of atmospheric air.

The savannah climate has two distinct seasons:

1. Winter season. Lasts from November to April. It is characterized by a dry climate. Little precipitation - no more than 100 mm. There is often no precipitation at all. The average air temperature is 21 ºС. Savannah dries out completely, which contributes to the spread of fires. The beginning of the winter season coincides with the arrival of the wet atmospheric precipitation, strong winds and thunderstorms.
2. Summer season. Dry tropical air dominates. The climate resembles a tropical one - high humidity and very hot. Regular heavy rainfall occurs from May to June. Until October, the territory receives a lot of precipitation - from 250 to 700 mm. Precipitation falls every day, most often in the afternoon.

The air temperature throughout the year ranges from +18 ºС to +32 ºС. The transition from one seasonal temperature to another occurs gradually. Daily temperature fluctuations can reach significant differences.

As you move away from the equator, the rainy season decreases from 8-9 months to 2-3 months. The annual amount of precipitation also decreases - from 2000 mm to 250 mm.

Savannah soils depend on the length of the rainy season and are characterized by a leaching regime. In areas where the rainy season is about 8 months, ferralite soils have formed near the equatorial forests. In areas where it rains for less than 6 months, the soils are red-brown. On the borders with semi-deserts, the soils contain a thin layer of humus and are unproductive.

Savannah zones of individual continents

The savannah zone is located in the Southern Hemisphere and includes:

• Africa;
• South America (Brazilian Highlands - Campos, Orinoco Valley - Llanos);
• north and east of Asia (Indo-Gangetic plain, Deccan plateau, Indo-China peninsula);
• Australia.

Savannah borders are usually deserts, humid grasslands, or dry rainforests.

Savannahs of Africa... A zone located in the subequatorial belt. Occupies more than 40% of the entire territory of Africa. The climate is warm tropical with a pronounced winter period. The average temperature of the hottest month is +30 ºС and more, and the coldest month is +18 ºС. The average annual rainfall is 2500 mm.

The soil contains practically no nutrients. During the rainy season, the soils become waterlogged, and during drought, they dry out completely with the formation of large cracks.

The most striking representative of the flora of the African savannah is the baobab. Its bark and thick trunk are capable of holding a large number of moisture, and powerful and long roots suck water from the depths of the earth. A large variety of different herbs: cereals, wild asparagus, aloe, elephant grass. The savannah is home to many palms, thorny shrubs (especially mimosa and acacia).

The vastness of the African savannah is inhabited by: giraffes, elephants, antelopes, monkeys, hyenas, lions, jackals, cheetahs, servals, etc.

Savannahs of South America... On the Brazilian Highlands, savannahs are located mainly in the interior. Savannahs are also found in the Guiana Plateau and Orinoco Lowlands. For Brazil, savannas with red ferralite soils are typical. The vegetation is represented by cereals, legumes, and asteraceae plants. Trees and shrubs are found only in the form of representatives of mimosa, succulents, milkweed, tree cacti and xerophytes.

The northeastern regions of the Brazilian plateau are occupied by caatinga (a rare forest of drought-resistant trees and shrubs growing on red-brown soils). Palm trees are also found here.

The savannahs of the Gran Chaco regions are represented by sparse forests and thickets of thorny bushes, among which a tree from the mimosa family - algarrobo, is often found. Low forest layers form impenetrable thickets.

In the savannas of South America, ocelot, armadillo, pampas deer, Magellan cat, pampa cat, beavers, rhea, whiskach, tuko-tuko, etc. are widespread.

Savannahs of Asia... As a rule, they are of secondary origin, their occurrence is associated with anthropogenic activities... The most common vegetation: dalbergia, butaea, lard. The grass cover is high and can reach 1.5-2 meters. Very common: Alang-Alang cereal, wild sugarcane, miscanthus, bearded vulture, milkweed, etc. Savannahs of Asia are very similar to those of Africa. Acacias are often found against the background of grasses. Animal world represented by rhinos, buffaloes, bulls, antelopes, deer, jackals, hyenas, caracals and other representatives.

Savannah Australia... They are located mainly in the eastern regions of the mainland. Typical trees are casuarines, eucalyptus, acacia trees. From herbaceous plants common cereals, buttercups, orchids, liliaceae. Lots of bottle trees, eucalyptus. Eucalyptus woodlands are found mostly in northern Australia and Cape York Island.

Many rodents live in the Australian savannas: rats, moles, wombats, anteaters. There is an echidna.

Savannah is one of the most popular landscapes on the African continent. At the same time, savannah is present not only in Africa, but also on the South American continent, in Australia and even in Asia - in the subequatorial belt.

Like the inhabitants of the steppe, the inhabitants of the savannah have to adapt to difficult climatic conditions.

Savannah characteristics

Its features are as follows:

• The life of the flora of the savanna is directly dependent on weather conditions.
• During a drought, the landscape loses its colors, the grass becomes dry.
• Vegetation is adapted to constant heat and lack of moisture.
• Grasses grow in turf.
• Leaves covered with waxy bloom are narrow and dry.
• Many species contain essential oils in abundance.
• The main representatives of the flora are cereals, bushes and trees are much less common.

Savannah herbs

Herbs of the Savannah flora mostly hard-skinned grasses, there are also perennials, and during periods of rainy, when the territory is flooded, even sedges grow here. Lichens and mosses are very rare and can only be seen on rocks.

Of the grasses for this African landscape, the most inherent elephant grass... The plant got its name due to the fact that it is a favorite delicacy of the giants-elephants. In the rainy season, this grass can grow up to 3 meters in height, and in dry times, ground shoots dry up, often die from fires. But due to the fact that the root system remains alive, in more humid conditions, elephant grass grows back. The shoots of this plant are often used by local residents for food.

Bermuda grass (fingered pig) forms a dense carpet, grows in open areas, constantly exposed to threats - floods, grazing animals, fires. However, the plant has adapted well to survival in difficult conditions: roots up to 1.5 meters long go deep underground, finding life-giving moisture there. The plant is considered a weed, which is very difficult to control without special equipment, but at the same time, it very effectively protects the soil from erosion and serves as food for many animals, including sheep.

Savannah trees

More often, the trees of the savanna are undersized, they are often entwined with vines.

Most often you can see the famous baobab, a tree with a thick trunk, more than 29 meters high. It is characterized by a spreading crown. This giant also has the name of the monkey tree, as these primates love to feast on its fruits.

The flowering period takes several months, but the life of each flower is fleeting, only one night. Bats pollinate the plant. The thick trunk protects the plant from fires, which are not uncommon in the savannah, and is also capable of long time hold, like a sponge, moisture accumulated during the rainy season. The length of the roots of this tree often reaches 10 meters.

Man widely uses baobab in his activities, eating leaves, making paper, cloth and rope from the bark, and the substance obtained from the seeds of the tree is a powerful antidote.

Oil palm- another representative of the flora of the savannah, different long term life, from 80 to 100 years, from its juice is obtained palm wine, and the pulp of the pericarp is used in the manufacture of soap.

Mongongo... This is a plant of the Euphorbiaceae family, reaching a height of 30 m. It has finger-cut leaves and flowers collected in inflorescences. The fruits are actively consumed by indigenous people. This tree can live in the savannah thanks to its long roots that go deep into the soil, as well as the ability of the trunk to absorb and retain moisture.

Acacia... Acacia savannas look amazing, on which several species of this tree grow:

• whitish;
• senegalese;
• twisted;
• acacia giraffe.

The plant has a slightly flattened crown shape, therefore it is often called umbrella-shaped. Thanks to such a flat and wide crown of acacia, it creates a shade under which herbs grow, hiding from the scorching sun. Senegalese acacia - a small tree, a representative of the legume family, it reaches a height of no more than 6 m, while the trunk diameter is about 30 cm. This acacia has thorns. The benefits of the tree are great: accumulating nitrogen, like other legumes, Senegalese acacia enriches poor soils, and its pods and leaves are absorbed by the savanna fauna.

Spun acacia can withstand heat and drought well. Its wood has found application in furniture production and construction.

Acacia wood is used to make high-quality furniture at a high price, and the bark is actively used in industry due to the adhesives it contains.

Persimmon medlar- a representative of the African savannah, this is a plant from the Ebony family, a deciduous tree, the bark of which is painted gray. The average trunk height is no more than 6 meters, but some trees manage to grow up to 25 meters. It has dark green leaves, in the rainy season it blooms with cream flowers, fruits appear only on female trees, they gradually ripen, changing color from light yellow to purple.

Red-leaved combretum grows near rivers, the average height of the tree is from 7 to 10 meters, the crown is dense. The roots are long, the fruits are poisonous. The leaves of the plant are used as food for giraffes, and people use parts of the tree for industry and medicine.

Most often, trees grow singly, less often in small groups. In the savannas of Brazil, you can often find real forests, albeit rare. The herbaceous and semi-shrub cover here is about a meter.

A clear division into two seasons - winter dry and summer rainy - is the main climate feature to which the savannah vegetation has learned to adapt.

Introduction

Today, grassy plains occupy a quarter of all land. They have many different names: steppes - in Asia, llanos - in the Orinoco basin, veld - in Central Africa, savannah - in the eastern part African continent... All of these areas are very fertile. Individual plants live up to several years, and when they die, they turn into humus. Among the tall grasses are legumes, vetch, daisies and small flowers.

The name "grass" unites many of the most variety of plants... This family is perhaps the largest in everything. plant kingdom, it includes over ten thousand species. Herbs are the product of a long evolution; they are able to survive fires, droughts, floods, therefore they only need abundance sunlight... Their flowers, small and inconspicuous, are collected in small inflorescences at the top of the stem and are pollinated by the wind, without requiring services from the birds. bats or insects.

Savannah is a community of tall grasses and open woodlands with low or medium, fire-resistant trees. It is the result of the interaction of two factors, namely soil and rainfall.

Savannah's significance lies in preserving rare species animals and plants. Therefore, the study of the African savannah is relevant.

The object of research is the African savannah

The subject of this research is the study of the natural features of the African savannah.

The purpose of this term paper is a comprehensive study of the types of savannahs in Africa.

The main tasks of the work are as follows:

1.Consider the geographical location of the African savannas.

2.Study the animal and vegetable world savannah.

.Consider the features of different types of African savannahs.

.Consider modern environmental problems and ways to solve them on the territory of savannahs.

Chapter I. General characteristics of the savannas of Africa

.1 Geographical position and climatic features of African savannas

Savannah is a zonal type of landscape in tropical and subequatorial zones, where the change of wet and dry seasons is clearly expressed at invariably high air temperatures (15-32 ° С). With distance from the equator, the period of the wet season decreases from 8-9 months to 2-3 months, and precipitation - from 2000 to 250 mm per year. Violent development of plants in the rainy season is replaced by droughts of the dry period with a slowdown in tree growth, burning out of grass. As a result, a combination of tropical and subtropical drought-resistant xerophytic vegetation is characteristic. Some plants are capable of storing moisture in their trunks (baobab, bottle tree). The grasses are dominated by tall grasses up to 3-5 m, among them are rarely growing shrubs and single trees, the occurrence of which increases towards the equator as the wet season lengthens to sparse forests.

Vast spaces of these amazing natural communities are located in Africa, although there are savannas in South America, Australia, and India. Savannah is the most widespread and most characteristic landscape in Africa. The savannah zone is surrounded by a wide belt of the Central African rainforest. In the north with rainforest bordering the Guinean-Sudanese savannas, stretching in a strip 400-500 km wide for almost 5000 km from the Atlantic to the Indian Ocean, interrupted only by the White Nile Valley. From the Tana River, the savannahs descend in a belt up to 200 km wide to the south to the valley of the Zambezi River. Then the savanna belt turns to the west and, sometimes narrowing, then expanding, extends for 2500 km from the shores of the Indian Ocean to the Atlantic coast.

Forests in the border zone are gradually thinning out, their composition becomes poorer, spots of savannah appear among the massifs of continuous forest. Gradually, the humid tropical forest is limited only by river valleys, and on the watersheds they are replaced by forests that shed their leaves during the dry season, or savannas. Vegetation changes occur as a result of a decrease in the wet season and the appearance of a dry season, which becomes longer and longer with distance from the equator.

The savannah zone from northern Kenya to the sea coast of Angola is the largest plant community on our planet in terms of area, occupying at least 800 thousand km 2... If we add another 250 thousand km2 of the Guinean-Sudanese savanna, it turns out that more than a million square kilometers of the Earth's surface is occupied by a special natural complex - the African savanna.

A distinctive feature of savannas is the alternation of arid and wet seasons, which take about six months, replacing each other. The fact is that for the subtropical and tropical latitudes, where the savannahs are located, the change of two different air masses is characteristic - the humid equatorial and dry tropical. Significantly affect the climate of the savannahs monsoon winds bringing seasonal rains. Since these landscapes are located between very humid natural zones of equatorial forests and very dry zones of deserts, they are constantly influenced by both. But moisture is not present long enough in savannas for multi-tiered forests to grow there, and dry "winter periods" of 2 - 3 months do not allow the savannah to turn into a harsh desert.

The annual rhythm of life of the savannah is associated with climatic conditions... During the wet period, the riot of grass vegetation reaches its maximum - the entire space occupied by savannas turns into a living carpet of forbs. The picture is disturbed only by dumpy, low trees - acacias and baobabs in Africa, fan palms ravala in Madagascar, cacti in South America, and in Australia - bottle trees and eucalyptus trees. Savannah soils are fertile. During the rainy season, when the equatorial air mass and both the land and the plants get enough moisture to feed the many animals that live here.

But now the monsoon leaves, and dry tropical air takes its place. Now the time for testing begins. The grasses that have grown to the size of human growth are dried up, trampled by numerous animals moving from place to place in search of water. Cereals and shrubs are very susceptible to fire, which often burns large areas. This is "helped" by the indigenous people who hunt: specially setting fire to the grass, they drive their prey in the direction they need. People have done this for many centuries and greatly contributed to the fact that the vegetation of the savannah acquired modern features: Abundant fire resistant trees with thick bark like baobabs, widespread plants with strong root systems.

The dense and tall grass cover provides abundant food for the largest animals such as elephants, giraffes, rhinos, hippos, zebras, antelopes, which in turn attract large predators such as lions, hyenas and others. The savannahs are home to the most big birds- the ostrich in Africa and the South American condor.

Thus, Savannahs in Africa occupy 40% of the continent. Savannah fringes woodlands Equatorial Africa and extend through Sudan, East and South Africa beyond the southern tropic. Depending on the duration of the rainy season and the annual amount of precipitation, they distinguish between tall-grass, typical (dry) and deserted savannas.

In the savannah zones:

the duration of the rainy period ranges from 8-9 months at the equatorial borders of the zones to 2-3 months at the outer borders;

the water content of rivers fluctuates sharply; in the rainy season, there is a significant solid runoff, slope and plane washout.

parallel to the decrease in annual precipitation, the vegetation cover is changing from tall-grass savannas and savanna forests on red soils to desertified savannas, xerophilic woodlands and shrubs on brown-red and red-brown soils.

Savannah africa climatic geographic

1.2 The flora of the savannahs

An abundance of tall grasses gilded by the sun rare trees and shrubs, which are more or less common depending on the area - such is the savannah, which occupies most of sub-Saharan Africa.

Savannah zones are quite extensive, so the vegetation on their southern and northern borders is somewhat different. Savannahs, bordering the desert zone in the north of the zone in Africa, are rich in drought-resistant low grasses, milkweed, aloe and acacias with highly branched roots. To the south, they are replaced by moisture-loving plants, and along the banks of the rivers, gallery forests with evergreen shrubs and lianas, similar to moist equatorial ones, enter the savanna zone. The largest lakes of the mainland are located in the rift valley of East Africa - Victoria, Nyasa, Rudolf and Albert lakes, Tanganyika. Savannahs on their banks alternate with wetlands where papyrus and reeds grow.

In the African savannas are many famous reserves and national parks. One of the most famous is the Serengeti, located in Tanzania. Part of its territory is occupied by the crater highlands - a famous plateau with ancient craters of extinct volcanoes, one of which, Ngorongoro, has an area of ​​about 800 thousand hectares.

The vegetation of the savanna corresponds to the hot, with prolonged dry periods, the climate that prevails in tropical areas. Therefore, savannah is widespread in different parts of the world, including South America and Australia. But it occupies the most extensive territories, of course, in Africa, where it is represented in all its diversity.

The general appearance of savannas is different, which depends, on the one hand, on the height of the vegetation cover, and on the other hand, on the relative amount of grasses, other perennial grasses, semi-shrubs, shrubs and trees. The grass cover is sometimes very low, even pressed to the ground.

A special form of savannas is made up of the so-called llanos, where trees are either completely absent, or are found in a limited number, with the exception of only damp places where palms (Mauritia flexuosa, Corypha inermis) and other plants form whole forests (however, these forests do not belong to savannas ); in llanos there are sometimes single specimens of Rhopala (trees from the Proteaceae family) and other trees; sometimes the cereals in them form a cover in the height of a person; Compositae, legumes, labiates, etc. grow between grasses. In the rainy season, many llanos are flooded by the floods of the Orinoco River.

The vegetation of the savannas is generally adapted to the dry continental climate and to the periodic droughts that occur in many savannas for months. Cereals and other grasses rarely form creeping shoots, but usually grow in turf. The leaves of cereals are narrow, dry, tough, hairy, or covered with a waxy coating. In cereals and sedges, young leaves remain rolled up into a tube. In trees, the leaves are small, hairy, shiny ("varnished") or covered with a waxy bloom. The vegetation of the savannah generally has a pronounced xerophytic character. Many species contain large amounts of essential oils, especially those of the vervain, labiate and myrtle families of the blazing continent. The growth of some perennial grasses, semi-shrubs (and shrubs) is especially peculiar, namely, the fact that the bulk of them, which is in the ground (probably the stem and roots), grows strongly into an irregular tuberous ligneous body, from which then numerous, mostly unbranched or weakly branched offspring. In the dry season, savannah vegetation freezes; Savannahs turn yellow, and dried plants are often exposed to fires, due to which the bark of trees is usually scorched. With the onset of rains, savannahs come to life, covered with fresh greenery and dotted with numerous different flowers.

In the south, on the border with the equatorial rainforests, the transition zone begins - the forest savannah. There are not very many grasses there, the trees grow densely, but they are not large. Then comes the sparsely wooded savannah - vast expanses overgrown with tall grasses, groves or freestanding trees. It is dominated by baobab trees, as well as palm, euphorbia and various types of acacia. Gradually, trees and shrubs become more rare, and grasses, especially giant grasses, thicken.

And finally, near the deserts (Sahara, Kalahari) the savanna gives way to a withered steppe, where only bunches of dry grass and undersized thorny bushes grow.

.3 Savannah fauna

The fauna of the savanna is a unique phenomenon. In no corner of the Earth in the memory of mankind has there been such an abundance of large animals as in the African savannas. Even at the beginning of the XX century. countless herds of herbivores roamed the vast savannahs, moving from one pasture to another or in search of watering holes. They were accompanied by numerous predators - lions, leopards, hyenas, cheetahs. The predators were followed by carrion eaters - vultures, jackals.

Seasonally dry tropical regions of Africa from light deciduous forests and woodlands to low-growing thorny forests and sparse Sahelian savannah differ from evergreen forests, first of all, by the presence of a well-pronounced dry period unfavorable for animals. This determines the clear seasonal rhythm of most forms, synchronous with the rhythm of moisture and vegetation vegetation.

In the dry season, most of the animals stop breeding. Some groups, mainly invertebrates and amphibians, take refuge in shelters during drought and hibernate. Others store food (ants, rodents), migrate (locusts, butterflies, birds, elephants and ungulates, beasts of prey) or concentrate on small areas - stations of experience (the vicinity of water bodies, drying up channels with closely located groundwater, etc.).

Animals appear in large numbers, building solid shelters. Strong cone-shaped termite mounds, which are more than 2 m high, are striking. The walls of these structures seem to be made of cement or baked clay, and they can hardly be pierced with a crowbar or a pickaxe. The above-ground dome protects the numerous chambers and passages located below both from drying out in the hot season and from rainstorms during wet times. Termite moves inland reach the aquifers of the soil, during a drought it remains in the termite mound. favorable treatment humidity. Here, the soil is enriched with nitrogen and ash elements of plant nutrition. Therefore, trees are often renewed on destroyed and near inhabited termite mounds. Of vertebrates, a number of rodents and even predators build burrows, ground and tree nests. The abundance of bulbs, rhizomes and seeds of grasses and trees allows them to store these feeds for future use.

The layered structure of the animal population, characteristic of evergreen forests, in seasonally dry forests, light forests, and especially in savannas, is somewhat simplified due to a decrease in the proportion of arboreal forms and an increase in those living on the surface and in the grass layer. However, the significant heterogeneity of vegetation caused by the mosaic of woody, shrub and herbaceous phytocenoses causes a corresponding heterogeneity of the animal population. But the latter has a dynamic character. Most of the animals are alternately associated with one or another plant group. Moreover, movements are not only on the scale of the seasons, but even within a day. They cover not only herds of large animals and flocks of birds, but also small animals: molluscs, insects, amphibians and reptiles.

Savannahs, with their huge food resources, are full of herbivores, especially antelopes, of which there are more than 40 species. Until now, in some places, there are herds of the largest wildebeest with a large mane, a powerful tail and horns bent down; Kudu antelopes with beautiful spiral horns, cannes, etc. are also widespread. There are also dwarf antelopes, reaching a length of a little more than half a meter.

The animals of the African savannas and semi-deserts, giraffes, rescued from extinction are remarkable, they are preserved mainly in national parks. Long neck helps them to get and gnaw young shoots and leaves from trees, and the ability to run quickly is the only defense against pursuers.

In many areas, especially in the east of the continent and south of the equator, African wild zebra horses are common in savannas and steppes. They are hunted mainly for their strong and beautiful hides. In some places, domesticated zebras replace horses as they are immune to the bite of the tsetse fly.

Until now, African elephants have survived - the most remarkable representatives of the fauna of the Ethiopian region. They have long been exterminated because of their valuable tusks, and in many areas they have completely disappeared. Elephant hunting is currently banned throughout Africa, but the ban is often violated by ivory poachers. Elephants are now found in the least populated mountain areas, in particular in the Ethiopian Highlands.

In addition, they live in the national parks of Eastern and South Africa where their livestock is even increasing. But still existence african elephant as a biological species in recent decades has been under a real threat, which can only be prevented by active joint activities of national and international organizations. Endangered animals include rhinos, which lived in the eastern and southern parts of the continent. African rhinos have two horns and are represented by two species - black and white rhinoceros. The last one is the largest of modern species and reaches a length of 4 m. Now it has survived only in protected areas.

Much more widespread are hippos living along the banks of rivers and lakes in different parts of Africa. These animals, as well as wild pigs, are exterminated for their edible meat and also for their skin.

Herbivores serve as food for numerous predators. In the savannas and semi-deserts of Africa, lions are found, represented by two species: the Berberian, living north of the equator, and the Senegalese, common in the southern part of the mainland. Lions prefer open spaces and hardly enter forests. Hyenas, jackals, leopards, cheetahs, caracals, and servals are widespread. There are several members of the civet family. In the plain and mountain steppes and savannas, there are many monkeys belonging to the baboon group: the real Raigo baboons, geladas, mandrills. Of the thin-bodied monkeys, the Gerets are characteristic. Many of their species live only in cool mountain climates, as they do not tolerate the high temperatures of lowlands.

Among rodents, mice and several types of squirrels should be noted.

Birds are numerous in the savannahs: African ostriches, guinea fowl turachi, marabou, weavers, a secretary bird that feeds on snakes is very interesting. Lapwings, herons, pelicans nest near the reservoirs.

There are no less reptiles than in the northern deserts; they are often represented by the same genera and even species. Many different lizards and snakes, land turtles... Some types of chameleons are also characteristic. Crocodiles are found in the rivers.

The great mobility of animals makes the savannah highly productive. Wild ungulates are almost constantly on the move, they never knock out pastures the way livestock does. Regular migrations, i.e. movements, of herbivorous animals of the African savannah, covering hundreds of kilometers, allow vegetation to fully recover in a relatively short term... Not surprisingly, in last years the notion that intelligent, scientifically based exploitation of wild ungulates promises great prospects than traditional cattle breeding, primitive and unproductive. Now these issues are being intensively developed in a number of African countries.

Thus, the fauna of the savanna has been developing for a long time as a single independent whole. Therefore, the degree of adaptation of the entire complex of animals to each other and of each individual species to specific conditions is very high. These devices include, first of all, a strict separation according to the method of feeding and the composition of the main feed. The vegetation cover of the savannah can only feed a huge number of animals because some species use grass, others use young shoots of shrubs, others use bark, and still others use buds and buds. Moreover, different species of animals take the same shoots from different heights. Elephants and giraffes, for example, feed at the height of the crown of a tree, a giraffe gazelle and a large kudu reach shoots located one and a half to two meters from the ground, and a black rhino, as a rule, plucks off shoots near the ground. The same division is observed in purely herbivores: what the wildebeest likes does not attract the zebra at all, and the zebra, in turn, happily nibbles the grass, past which the gazelles pass indifferently.

Chapter II. Features of types of African savannahs

.1 Tall grass wet savannas

High-grass savannas are various combinations of grassy vegetation with islands of forest or individual specimens of trees. The soils that form under these landscapes are referred to as the red or ferralitic soils of seasonally humid tropical forests and tall grass savannas.

The tall grass savannas are wet. Very tall grasses grow in them, including elephant grass, reaching 3 m in height. Among these savannahs are scattered massifs of park forests, gallery forests stretch along riverbeds.

Tall grass savannas occupy an area where the annual precipitation is 800-1200 mm, and the dry season lasts 3-4 months, they have a dense cover of tall grasses (elephant grass up to 5 m), groves and massifs of mixed or deciduous forests on watersheds, gallery evergreen forests soil moisture in the valleys. They can be called a transition zone from forest vegetation to typical savannah. Among the continuous cover of high (up to 2-3 m) grasses, trees (usually deciduous species) rise. The tall grass savanna is characterized by baobabs, acacia, and terminalia. Red lateritic soils are most common here.

There is an opinion that the wide distribution of moist tall-grass savannas, replacing deciduous-evergreen forests, is associated with human activities, who burned vegetation during the dry season. The disappearance of the closed tree layer contributed to the appearance of countless herds of ungulates, as a result of which the renewal of tree vegetation became impossible.

The Sahelian savannas and, to a lesser extent, the thorny forests of Somalia and Kalahari are faunistically depleted. Many of the animals close to or in common with forest animals disappear here.

2.2 Typical cereal savannahs

The zone of grass savanna begins from the border of the gili. Typical (or dry) savannas are replaced by tall grass in areas where the rainy season lasts no more than 6 months. The grasses in such savannas are still very dense, but not very high (up to 1 m). Herbaceous spaces alternate with light forests or individual groups of trees, among which numerous acacias and giant baobabs, or monkey breadfruit, are especially typical.

Typical grassland savannas are developed in areas with an annual rainfall of 750-1000 mm and a dry period of 3 to 5 months. In typical savannas, a continuous grass cover is not higher than 1 m (species of bearded vulture, temeda, etc.), from tree species palm trees (fan, hyphaena), baobabs, acacias are characteristic, in East and South Africa - milkweed. Most of the wet and typical savannas are of secondary origin. In Africa, north of the equator, savannahs extend in a wide strip from the Atlantic coast to the Ethiopian Highlands, south of the equator they occupy the north of Angola. The height of wild-growing grasses reaches 1-1.5 m, and they are represented mainly by hyperrenia and bearded vultures.

A typical grass savanna is a space completely covered with tall grasses, a predominance of grasses, with sparsely standing individual trees, shrubs or groups of trees. Most of the plants are hydrophytic in nature due to the fact that during the rainy season, the air humidity in the savannas resembles a tropical forest. However, plants also appear of a xerophytic nature, adapting to the transfer of dry triode. In contrast to hydrophytes, they have smaller leaves and other adaptations to reduce evaporation.

During the dry season, the grasses burn out, some types of trees shed their foliage, although others lose it only shortly before the appearance of a new one; the savannah becomes yellow; dried grass is burned annually to fertilize the soil. The harm that these fires bring to vegetation is very great, since it disrupts the normal cycle of winter dormancy for plants, but at the same time it also causes their vital activity: after a fire, young grass quickly appears. When it rains, grasses and other grasses grow amazingly quickly and the trees become leafy. In the grass savanna, the grass cover reaches heights of 2-3 m , and in low places 5 m .

Typical cereals are: elephant grass, Andropogon species, etc., with long, wide, hairy leaves of a xerophytic appearance. Of the trees, the oil palm 8-12 m should be noted heights, pandanus, oil tree, Bauhinia reticulata - evergreen tree with wide leaves. Baobab and various types of dum palm are not uncommon. Along the river valleys, several kilometers wide gallery forests, reminiscent of giles, with many palms, stretch.

Grass savannas are gradually replaced by acacia ones. They are characterized by a continuous cover of cereals of a lower height - from 1 to 1.5 m ; of the trees, they are dominated by various species of acacias with a dense umbrella-shaped crown, for example, species: Acacia albida, A. arabica, A. giraffae, etc. In addition to acacias, one of the characteristic trees in such savannas is the baobab, or monkey breadfruit, reaching 4 min diameter and 25 m height, containing a significant amount of water loose fleshy trunk.

In the grass savanna, where the rainy period lasts 8-9 months, there are grasses 2-3 m high, and sometimes up to 5 m high: elephant grass (Pennisetum purpureum), a bearded man with long hairy leaves, etc. Among continuous sea cereals, individual trees rise: baobabs (Adansonia digitata), doom palms (Hyphaene thebaica), oil palms.

North of the equator, the grass savannas reach about 12 ° N. In the southern hemisphere, the zone of savannas and woodlands is much wider, especially off the shores of the Indian Ocean, where it extends in places to the tropics. The difference in moisture conditions in the northern and southern parts of the zone suggests that mesophilic deciduous forests grew in the more humid northern regions, and xerophytic light forests with a predominance of representatives of the legume family (Brachystegia, Isoberlinia) occupied only the southern regions of their modern distribution. To the south of the equator, this plant formation is called the "miombo" woodlands. The expansion of its range can be explained by its resistance to fires and a high rate of renewal. In eastern South Africa, light forests are found in combination with other types of vegetation significantly south of the tropics.

Under the grass savannas and woodlands, special types of soils are formed - red soils under savannas and red-brown soils under forests.

In drier areas, where the rainless period lasts from five to three months, dry thorny semi-savannah prevails. For most of the year, trees and shrubs in these areas are leafless; low grasses (Aristida, Panicum) often do not form a continuous cover; among the cereals grow low up to 4 m heights, thorny trees (species Acacia, Terminalia, etc.)

This community is also called steppe by many researchers. This term is widespread in the literature on African vegetation, but does not fully correspond to the understanding of our term "steppe".

Dry thorny semi-savannas are replaced with distance from the acacia savannas of the so-called thorny shrub savanna. It reaches 18-19 ° S. sh., occupying most of the Kalahari.

2.3 Deserted savannah

In areas with a wet period duration of 2-3 months. typical savannahs turn into thickets of thorny bushes and hard grasses with sparse sod. As the wet period decreases to 3-5 months. and the general decrease in precipitation, the grass cover becomes more rarefied and stunted, various acacias prevail in the composition of tree species, low, with a kind of flat crown. Such plant communities, called deserted savannas, form a relatively narrow strip in the northern hemisphere north of typical savannas. This strip expands from west to east in the direction of decreasing annual precipitation.

In the deserted savannas, scanty rains are rare and occur only for 2-3 months. The strip of these savannas, stretching from the coast of Mauritania to Somalia, expands to the east of the African continent, and this natural zone also covers the Kalahari Basin. The vegetation here is represented by sod grasses, as well as thorny bushes and low leafless trees. In typical and deserted savannas, tropical red-brown soils are developed, not rich in humus, but having powerful alluvial horizons. In the places where the main rocks and lava covers develop - in the southeast of Sudan, in Mozambique, Tanzania and the Shari River basin - large areas are occupied by black tropical soils, akin to chernozems.

In such conditions, instead of a continuous herbaceous cover, only sod grasses and leafless and thorny shrubs remain. The belt of semi-deserts or deserted savannas in the Sudanese plains is called "sahel", which in Arabic means "coast" or "edge". This is really the edge of green Africa, beyond which the Sahara begins.

In the east of the mainland, deserted savannas occupy especially large areas, covering the Somali peninsula and extending to the equator and south of it.

Deserted savannas are typical for areas with an annual precipitation of no more than 500 mm and a dry period lasting from 5 to 8 months. Deserted savannas have a sparse grass cover; thickets of thorny bushes (mainly acacias) are widespread in them.

Despite a number of common features, savannahs are distinguished by significant diversity, which greatly complicates their separation. There is a point of view that most of the savannahs in Africa arose on the site of destroyed forests and only deserted savannas can be considered natural.

Chapter ІІІ. Ecological problems of the savannahs of Africa

.1 The role of humans in the savannah ecosystem

Among the biocenoses of the land, the steppes produce the largest biomass of animals per unit surface, therefore, for a long time they attracted a person who lived mainly by hunting. This erect primate by nature itself was created for life in the steppes, and it was here, in the struggle for food and shelter, fleeing from enemies, he turned into a rational creature. However, as he improved, man became more and more sophisticated in his weapons and invented new methods of hunting for herbivores and predatory animals, which played a fatal role for many of them.

Whether ancient man was already involved in the extermination of a number of animal species is a moot point. There are various, very contradictory opinions on this score. Some scientists believe that many of the inhabitants of the African savannas and steppes were destroyed already in the early Paleolithic, characterized by the use of a hand ax (the so-called Acheulean culture). As supporters of this opinion believe, the same thing happened in North America, when about 40 thousand years ago man first entered this continent through the Bering Bridge. At the end of the Ice Age, 26 African and 35 North American genera disappeared from the face of the Earth. large mammals.

Opposing viewers insist that ancient man with its still extremely imperfect armament, one cannot be considered guilty of their destruction. Mammals that became extinct at the end of the Ice Age are likely to have fallen prey global changes climate, affecting the vegetation that served them as food, or on their prey.

It was established that when, much later, well-armed people appeared in Madagascar, whose fauna did not know natural enemies, this led to very sad consequences. In Madagascar, in a relatively short period of time, at least 14 species of large lemurs, 4 species of giant ostriches were exterminated, and, in all likelihood, the same fate befell the aardvark and pygmy hippopotamus.

However, only when a white man used firearms, this led to a catastrophic imbalance between him and the world of large animals. To date, in all corners of the Earth, man has almost completely destroyed the large animals of the savannah, turned the once endless grassy plains into arable lands or pastures for livestock.

The destruction of the original vegetation has led to the disappearance of many small and medium-sized animals. Only in national parks and other protected areas are the remains of a unique community of living creatures that have been formed over millions of years. The hunter-man destroyed his ancestral homeland of the steppe and many animals generated by the amazing ecosystem of the savannah.

A hundred years ago, Africa was represented as a continent of untouched nature. However, even then, nature was significantly changed. economic activities person. At the beginning of the 21st century, environmental problems that arose during the predatory campaigns of the European colonialists became aggravated.

Evergreen forests have been cut down for centuries for the sake of mahogany. They were also uprooted and burned for fields and pastures. Burning out plants in slash-and-burn farming leads to disruption of the natural vegetation cover and deterioration of the soil. Its rapid depletion forced to leave the cultivated land in 2-3 years. Now almost 70% of Africa's forests have been destroyed, and their remnants continue to rapidly disappear. In place of forests, plantations of cocoa, oil palm, bananas, peanuts appeared. Deforestation leads to many negative consequences: an increase in the number of floods, an increase in droughts, the occurrence of landslides, and a decrease in soil fertility. Reproduction of the forests is very slow.

The nature of the savannas has also been significantly changed. Huge areas have been plowed up there, occupied by pastures. Overgrazing of cattle, sheep and camels, cutting down trees and shrubs, savannahs are increasingly turning into deserts. Especially the negative consequences of such land use are in the north, where the savannah passes into the desert. The expansion of desert areas is called desertification.

Aerospace images taken from artificial earth satellites have convincingly shown that in the last half century alone, the Sahara has moved southward by 200 km. and expanded its area by thousands of square kilometers.

On the border with deserts, forest shelter belts are planted, livestock grazing is limited in areas with a thin vegetation cover, and arid regions are irrigated. Large changes in natural complexes have occurred as a result of the extraction of minerals.

Long colonial past and irrational use natural resources led to a serious imbalance between the components of natural complexes. Therefore, in many African countries, the problems of nature protection have become acute.

3.2 The economic role of savannas

Savannahs play a very important role in human economic life. In terms of climatic and soil conditions, savannahs are favorable for tropical agriculture. Currently, significant areas of savannahs have been cleared and plowed up. Significant areas are plowed here, cereals, cotton, peanuts, jute, sugar cane and others are grown. Livestock raising is developed in drier areas. Some species of trees growing in savannas are used by humans for their own purposes. So, teak wood gives a hard, valuable wood that does not rot in water.

At present, we can say with full confidence that a significant part of the humid and dry savannas in Africa arose as a result of human activities in the place of mixed forests, almost disappeared deciduous forests and woodlands. Since the man learned how to make fire, he began to use it for hunting, and later for clearing thickets for arable land and pastures. For millennia, farmers and pastoralists have set fire to the savannah before the rainy season to fertilize the soil with ash. Arable land, which was rapidly losing fertility, was abandoned after several years of use, and new plots were prepared for crops. In the pasture areas, the vegetation suffered not only from burning out, but also from trampling, especially if the livestock population exceeded the fodder "capacity" of the pasture lands. The fire destroyed most of the trees. Mainly only some woody species adapted to fires survived, the so-called "fire-lovers", the trunk of which is protected by thick bark, which is charred only from the surface.

Plants that reproduce by root shoots or have seeds with a thick shell have also survived. Fire lovers include thick-bore giant baobabs, shea tree, or shea tree, called the butter tree, since its fruits produce edible oil, etc.

Fencing of private estates, laying roads, steppe fires, opening up large areas and expanding pastoralism exacerbated the plight of wildlife. Finally, the Europeans, unsuccessfully trying to fight the tsetse fly, staged a grand slaughter, and more than 300 thousand elephants, giraffes, buffaloes, zebras, wildebeest and other antelopes were shot from guns and machine guns from cars. Many animals died from the cattle-borne plague.

3.3 Conservation Actions to Conserve African Savannahs

The fauna of the African savannah is of great cultural and aesthetic importance. Untouched corners with pristine rich fauna literally attract hundreds of thousands of tourists. Every African reserve is a source of joy for many, many people. Now you can drive hundreds of kilometers through the savannas and not meet a single large animal.

Once virgin forests are mastered by man and are gradually uprooted to clear land, or are cut down for the purpose of procurement of building materials. Further, the soil, which is no longer strengthened by plant roots and protected by tree crowns, is eroded during tropical rains, and the natural landscape rich in the recent past becomes scarce, transforming into a barren desert.

Often interests wild inhabitants In Africa, they run counter to the needs of the local population, which makes it difficult to protect wildlife in Africa. In addition, environmental measures are also costly, and the government of far from every country can afford to finance them.

Nevertheless, some African states are concerned about the state of wild flora and fauna on their territory, therefore, increased attention is paid to nature protection. Wild animals are protected in the national parks of such countries, reservoirs are subject to cleaning for fish breeding, and comprehensive measures are taken to restore woodlands.

New governments independent states Africa, having thrown off the yoke of colonialism, strengthened and expanded the network of such reserves - the last refuge of wild animals. Only there can a person still admire the view of the primitive savannah. For this purpose, nature conservation areas are established - reserves and national parks. They protect the components of natural complexes (plants, animals, rocks and others) and research work is underway. The reserves have a strict environmental regime, and tourists who are required to follow the established rules can visit the national parks.

In Africa, protected areas cover large areas... They are located in various natural complexes - in the mountains, on the plains, in moist evergreen forests, savannas, deserts, on volcanoes. The national parks of the Serengeti, Kruger, Rwenzori are worldwide.

National nature Park Serengeti- One of the largest and most famous in the world. Translated from the Maasai language, its name means immensely plain. The park is located in East Africa... It is called the African animal paradise. Its vastness is inhabited by thousands of herds of large ungulates ( different types antelopes, zebras) and predators (lions, cheetahs, hyenas), which have been preserved intact as they have been since time immemorial.

National park Kruger- One of the oldest on the mainland. It originated in southern Africa back in 1898. Buffaloes, elephants, rhinos, lions, leopards, cheetahs, giraffes, zebras, various antelopes, from birds - marabou, a secretary bird, reign supreme in this region of the savannah. There are thousands of each animal species. In their diversity, the park is often compared to Noah's Ark.

Ngorongoro National Parklocated in the crater of an extinct volcano. Buffaloes, rhinos, antelopes, giraffes, hippos, and various birds are protected there.

Have Rwenzori Parkchimpanzee and gorilla apes are protected.

The creation of nature reserves and national parks contributes to the conservation rare plants, the unique fauna and individual natural complexes of Africa. Thanks to protective measures, the number of many species of animals that were on the verge of extinction has been restored. The world's largest species diversity makes Africa a true ecotourism's paradise.

Conclusion

The savannahs of Africa are the Africa of our imagination. Vast expanses of the earth, extraordinarily amazing fauna, the greatest herds on the planet. And everything seems to exist here outside of time.

Savannah is incredibly changeable, unstable. In this place, after a few years, it may appear dense forest... But there may be another development of events: all the trees will disappear, only the grass will remain.

Savannah life is subject to the weather, which is very capricious here. Every year there is a dry, sultry season. But no year is like the previous one.

The importance of savannas is enormous. This is, first of all, the biological value of the community as a habitat for many species of animals and plants, including those that are endangered. Also savannas, after the forest zone, give the greatest yield of plant products.

Sadly, the wildlife of Africa was once even more diverse. Currently, unfortunately, some of the species of wild flora and fauna have been completely destroyed, and some more are under threat of extinction.

A great misfortune for the inhabitants of the African savannas is the hunters who feed the commercial species of animals at the root. But no less problem was the advance of civilization to the original places. natural habitat representatives of the wild fauna of Africa. Traditional migration routes of wild animals turn out to be blocked roads, and new human settlements appear in places of wild thickets.

Now humanity understands the need to protect nature on Earth - one can hope that in the near future the wildlife of Africa will not only not suffer even more from human activities, but to some extent will restore its impoverished flora and fauna, returning it to its former splendor and diversity ...

List of sources

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Boris Zhukov Eden at the bottom of the boiler / Around the World No. 11, 2010 pp. 96-101

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Vladimir Korachantsev. Moscow. Armada Press, Africa-Land of Paradoxes (Green Series 2001. Around the World), 2001- 413p.

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