Small animals of the savannah. Fauna of the African savannah (the most, the most...)

Instructions

Nowhere in the world are there such numbers of large herbivores as in the African savannah. Huge herds of ungulates - zebras, gazelles, antelopes, buffaloes - constantly wander from place to place “following the rain,” eating and trampling grassy vegetation in huge quantities. A significant number of herbivores and their constant and seasonal migrations contribute to the preservation of the typical “park” appearance of the African savanna.

The largest inhabitant of savannahs is the African elephant. Its height reaches 4 m, and its weight is measured in tens of tons. Being a herbivore, the elephant is perfectly adapted to life in the shroud. The trunk allows it to reach the upper branches of plants that are inaccessible to other herbivores, and acts as a pump during watering and bathing.

Another typical representative of the savannah is the giraffe, the tallest animal on the planet. The giraffe is a herbivorous ungulate found only in Africa. Its height reaches 6 m and weighs almost a ton. Despite its very significant height and weight, the giraffe is capable of speeds of up to 60 km/h. But usually he is leisurely, running only when danger arises.

Black and white rhinoceros are typical representatives of the African savannah. Currently they are quite rare. The number of rhinoceroses has been greatly reduced due to their shooting by poachers.

Herds of herbivores are always accompanied by predators. There are 2 types of lions living here - Barbary and Senegalese. The first is north of the equator, the second is south. Another representative of predators is the cheetah - the fastest animal on the planet. During pursuit, a cheetah can reach speeds of up to 110 km/h. In addition to lions and cheetahs, there are quite a few other predators here - bush cats or servals, hyenas, jackals, hyena dogs.

African savannas are home to many birds. A significant portion of birds are migratory and periodically end up here as a result of their annual migrations. The original representative of the savannah, the African ostrich, is the largest representative of all living birds. The ostrich is a non-flying bird. His height reaches 250 cm and weight 150 kg. When running, it reaches speeds of up to 70 km/h, and is capable of abruptly changing the direction of running without slowing down.

Small birds are numerous - bustards, plovers, larks, hazel grouse, starlings, weavers, turtle doves, pigeons, kingfishers, hornbills, etc. A rain stork nests in the crowns of trees. Quite a lot of birds of prey - buzzard, secretary bird, black-winged kite, buffoon eagle, African kestrel, short-eared owl, five species of vultures that fly from Europe for the winter. There are also scavengers, typical representatives of which are the marabou stork and African vultures. The latter perform the role of orderlies in the shroud, since they feed exclusively on carrion.

Introduction

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

The name “grass” combines a wide variety of plants. This family is perhaps the largest in the entire plant kingdom, it includes more than ten thousand species. Herbs are the product of long evolution; They are able to survive fires, droughts, and floods, so they only need plenty of 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 the services of birds, bats or insects.

Savanna is a community of tall grasses and woodlands with low to medium-sized, fire-resistant trees. It is the result of the interaction of two factors, namely soil and precipitation.

The importance of savannas lies in the conservation rare species animals and plants. Therefore, the study of African savannas is relevant.

The object of study is African savannas

The subject of the research is the study of the natural features of African savannas.

The purpose of this course work is a comprehensive study of the types of savannas in Africa.

The main objectives of the work are the following:

1.Consider geographical location African savannas.

2.Explore the flora and fauna of savannas.

.Consider the features of different types of African savannas.

.Consider modern environmental problems and ways to solve them in the savannas.

Chapter I. General characteristics of African savannas

.1 Geographical location and climatic features of African savannas

Savannah is a zonal type of landscape in tropical and subequatorial zones, where the change in wet and dry seasons of the year is clearly expressed, with constant high temperatures ah air (15-32°C). As you move away from the equator, the period of the wet season decreases from 8-9 months to 2-3, and precipitation decreases from 2000 to 250 mm per year. The vigorous development of plants during the rainy season is replaced by droughts of the dry period with slower growth of trees and burning of grass. The result is a characteristic combination of tropical and subtropical drought-resistant xerophytic vegetation. Some plants are able to store moisture in their trunks (baobab, bottle tree). The grasses are dominated by tall grasses up to 3-5 m, among them are sparsely growing shrubs and single trees, the occurrence of which increases towards the equator as the wet season lengthens to open forests.

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

The forests in the border zone are gradually thinning out, their composition is becoming poorer, and patches of savannas are appearing among the tracts of continuous forest. Gradually the tropical rainforest is limited to only river valleys, and on watersheds they are replaced by forests that shed their leaves during the dry season, or savannas. The change in vegetation occurs as a result of a shortening of the wet period and the appearance of a dry season, which becomes longer and longer as it moves away from the equator.

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

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

The annual rhythm of life in savannahs 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 broken only by stocky, low trees - acacias and baobabs in Africa, fan palms in Madagascar, cacti in South America, and bottle trees and eucalyptus in Australia. The soils of the savannas are fertile. During the rainy season, when the equatorial air mass dominates, both the land and plants receive enough moisture to feed the numerous animals that live here.

But then the monsoon leaves, and dry tropical air takes its place. Now the testing time begins. Herbs that have grown to human height are dried out and trampled by numerous animals moving from place to place in search of water. Grasses and shrubs are very susceptible to fire, which often burns large areas. The indigenous people who hunt also “help” this: by deliberately setting the grass on fire, they drive their prey in the direction they need. People did this for many centuries and greatly contributed to the fact that savannah vegetation acquired modern features: an abundance of fire-resistant trees with thick bark, like baobabs, and a wide distribution of plants with a powerful root system.

Thick and tall grass cover provides abundant food for the largest animals, such as elephants, giraffes, rhinoceroses, hippopotamuses, zebras, antelopes, which in turn attract such large predators, like lions, hyenas and others. 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. Savannas frame the forests of Equatorial Africa and extend through Sudan, East and South Africa beyond the southern tropics. Depending on the duration of the rainy season and annual precipitation amounts, they are divided into tall grass, typical (dry) and desert savannas.

In savannah zones:

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

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

parallel to the decrease in annual precipitation, the vegetation cover changes 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 climate geographical

1.2 Flora of savannas

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

Savannah zones are quite extensive, so in their southern and northern borders the vegetation varies somewhat. Savannas, bordering the desert zone in the north of the zone in Africa, are rich in drought-resistant low grasses, milkweeds, aloe and acacia trees with highly branched roots. To the south they are replaced by moisture-loving plants, and along the banks of rivers gallery forests with evergreen shrubs and vines similar to wet equatorial ones. The Rift Valley of East Africa contains the most large lakes mainland - Victoria, Nyasa, Lakes Rudolf and Albert, Tanganyika. Savannahs on their banks alternate with wetlands where papyrus and reeds grow.

The African savannas are home to many famous nature 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.

Savannah vegetation corresponds to the hot climate with long dry periods that prevails in tropical places. That is why savanna 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, subshrubs, shrubs and trees. The grass cover is sometimes very low, even pressed to the ground.

A special form of savannas is the so-called llanos, where trees are either completely absent or found in limited numbers, with the exception of damp places where palm trees (Mauritia flexuosa, Corypha inermis) and other plants form entire forests (however, these forests do not belong to savannas ); in the llanos there are sometimes single specimens of Rhopala (trees from the family Proteaceae) and other trees; sometimes the grains in them form a cover as tall as a person; Between the cereals grow Compositae, legumes, Lamiaceae, etc. During the rainy season, many llanos are flooded by floods of the Orinoco River.

Savannah vegetation is generally adapted to dry conditions. continental climate and to periodic droughts that occur in many savannas for entire months. Cereals and other herbs rarely form creeping shoots, but usually grow in tussocks. The leaves of cereals are narrow, dry, hard, hairy or covered with a waxy coating. In cereals and sedges, young leaves remain rolled into a tube. Tree leaves are small, hairy, shiny (“varnished”) or covered with a waxy coating. The vegetation of savannas generally has a pronounced xerophytic character. Many species contain large amounts essential oils, especially the species of the families Verbenaceae, Lamiaceae and Myrtaceae of the flaming continent. The growth of some perennial herbs, semi-shrubs (and shrubs) is especially peculiar, namely in that the main part of them, located in the ground (probably the stem and roots), grows strongly into an irregular tuberous woody body, from which then numerous, mostly unbranched or weakly branched, offspring. During the dry season, savannah vegetation freezes; savannas turn yellow, and dried out plants are often exposed to fires, as a result of which the bark of trees is usually scorched. With the onset of rains, the savannas come to life, becoming covered with fresh greenery and speckled with numerous different flowers.

In the south, on the border with equatorial tropical forests, a transition zone begins - the forest savanna. There are not very many grasses there; trees grow thickly, but they are small. Then comes the sparsely forested savanna - vast spaces covered with tall grasses, with groves or isolated trees. The baobab tree predominates here, as well as palm, spurge and various types of acacia. Gradually, trees and shrubs become more and more sparse, and grasses, especially giant grasses, become denser.

And finally, near deserts (Sahara, Kalahari), the savannah gives way to a parched steppe, where only tufts of dry grass and low-growing thorny bushes grow.

.3 Savanna fauna

The fauna of the savannah is a unique phenomenon. In no corner of the Earth in human memory has there been such an abundance of large animals as in the African savannas. Back at the beginning of the 20th century. Countless herds of herbivores roamed the vast savannahs, moving from one pasture to another or in search of watering places. They were accompanied by numerous predators - lions, leopards, hyenas, cheetahs. The predators were followed by carrion eaters - vultures, jackals.

The 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 primarily by the presence of a well-defined dry period unfavorable for animals. This determines the clear seasonal rhythm of most forms, synchronous with the rhythm of moistening and vegetation growth.

During the dry season, most animals stop reproducing. Some groups, mainly invertebrates and amphibians, take refuge in shelters and hibernate during drought. Others stock up on food (ants, rodents), migrate (locusts, butterflies, birds, elephants and ungulates, predatory animals) or concentrate on small areas - stations of experience (surroundings of reservoirs, drying up riverbeds with nearby groundwater etc.).

IN large quantities animals appear, constructing solid shelters. The most striking are the strong cone-shaped termite mounds, which can be more than 2 m high. The walls of these structures seem to be made of cement or baked clay, and they can hardly be broken through with a crowbar or pickaxe. The above-ground dome protects the numerous chambers and passages located below both from drying out in the hot season and from downpours in humid times. Termite passages reach deep into the aquiferous layers of the soil; during drought, a favorable humidity regime is maintained in the termite mound. Here the soil is enriched with nitrogen and ash plant nutrients. Therefore, trees often regenerate on destroyed and near residential termite mounds. Among vertebrate animals, 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 this food for future use.

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

Savannas, with their enormous food resources, contain many 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, powerful tail and downward-curved horns; Kudu antelopes with beautiful helical horns, elands, etc. are also common. There are also dwarf antelopes, reaching a length of a little more than half a meter.

Remarkable animals of the African savannas and semi-deserts, saved from extinction, are giraffes; they are preserved mainly in national parks. The long neck helps them reach and gnaw young shoots and leaves from trees, and the ability to run quickly is the only means of protection from pursuers.

In many areas, especially in the east of the continent and south of the equator, African wild zebra horses are common in the savannas and steppes. They are hunted mainly for their durable and beautiful skins. In some places, domesticated zebras are replacing horses as they are not susceptible to tsetse fly bites.

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

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

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

Herbivores serve as food for numerous predators. In the savannas and semi-deserts of Africa there are lions, represented by two varieties: the Barbary, living north of the equator, and the Senegalese, common in the southern part of the continent. Leos prefer open spaces and they almost never go into the forests. Hyenas, jackals, leopards, cheetahs, caracals, and servals are common. There are several representatives of the civet family. In the lowland and mountain steppes and savannas there are many monkeys belonging to the group of baboons: real Raigo baboons, geladas, mandrills. Among the thin-bodied monkeys, the gverets are typical. Many of their species live only in cool mountain climates, as they cannot tolerate the high temperatures of the lowlands.

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

Birds are numerous in savannas: African ostriches, guinea fowls, marabou, weavers, a very interesting secretary bird that feeds on snakes. Lapwings, herons, and pelicans nest near ponds.

There are no fewer 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. There are crocodiles in the rivers.

The high mobility of animals makes the savanna highly productive. Wild ungulates are almost constantly on the move; they never graze pastures the way livestock do. Regular migrations, i.e. movements, of herbivores of the African savannah, covering hundreds of kilometers, allow vegetation to fully recover in a relatively short period of time. It is not surprising that in recent years the idea arose and strengthened that reasonable, on scientific basis exploitation of wild ungulates promises great prospects than traditional cattle breeding, which is primitive and unproductive. These issues are now being intensively developed in a number of African countries.

Thus, the fauna of the savannah developed over a long period of 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. Such adaptations 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 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 tree crown, the giraffe gazelle and the great kudu reach shoots located one and a half to two meters from the ground, and the black rhinoceros, as a rule, plucks shoots close to the ground. The same division is observed in purely herbivorous animals: what the wildebeest likes does not attract the zebra at all, and the zebra, in turn, happily nibbles the grass, past which gazelles pass indifferently.

Chapter II. Features of African savanna types

.1 Tall grass wet savannas

Tall grass savannas are various combinations of herbaceous vegetation with islands of forest or individual trees. The soils that form under these landscapes are called red or ferrallitic soils of seasonally wet tropical forests and tall grass savannas.

Tall grass savannas are wet. Very tall grasses grow in them, including elephant grass, reaching 3 m in height. Among such savannas, tracts of park forests are scattered, and gallery forests stretch along river beds.

Tall grass savannas occupy a space 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 tracts of mixed or deciduous forests on watersheds, gallery evergreens forests of ground moisture in the valleys. They can be called a transition zone from forest vegetation to a typical savanna. Among the continuous cover of tall (up to 2-3 m) cereals, trees (usually deciduous species) rise. The tall grass savanna is characterized by baobabs, acacias, and terminalias. Red lateritic soils are most common here.

There is an opinion that the widespread occurrence of moist tall-grass savannas replacing deciduous evergreen forests is associated with human activity, which burned vegetation during the dry season. The disappearance of the closed tree layer contributed to the emergence of countless herds of ungulates, as a result of which the regeneration of woody vegetation became impossible.

The Sahel savannas and, to a lesser extent, the thorny forests of Somalia and the Kalahari are faunally depleted. Here many of the animals that are close or common to forest animals disappear.

2.2 Typical grass savannas

The zone of grass savanna begins from the border of the gils. Typical (or dry) savannas give way to tall grass savannas in areas where the rainy season lasts no more than 6 months. The grasses in such savannas are still very thick, but not very tall (up to 1 m). Grassy spaces alternate with open forests or isolated groups of trees, among which numerous acacias and giant baobabs, or monkey breadfruit trees, are especially typical.

Typical grass savannas are developed in areas with an annual precipitation of 750-1000 mm and a dry period of 3 to 5 months. In typical savannas, the continuous grass cover is no higher than 1 m (species of bearded vulture, themeda, etc.), the typical tree species are palms (fan palms, hyphaenas), baobabs, acacias, and in East and Southern Africa - milkweeds. Most of the wet and typical savannas are of secondary origin. In Africa, north of the equator, savannas extend in a wide strip from the Atlantic coast to the Ethiopian Highlands, while south of the equator they occupy the north of Angola. The height of wild cereals reaches 1-1.5 m, and they are mainly represented by hyperrhenia and bearded vultures.

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

During the dry season, grasses burn out, some types of trees shed their leaves, although others lose them only shortly before new ones appear; the savannah turns yellow; dried grass is burned annually to fertilize the soil. The damage that these fires cause to vegetation is very great, since it disrupts the normal cycle of winter dormancy of plants, but at the same time it also causes their vital activity: after a fire, young grass quickly appears. When the rainy season comes, cereals and other herbs grow amazingly quickly, and trees become covered with leaves. In the grass savanna, the grass cover reaches a height of 2-3 m , and in low places 5 m .

The typical grasses here are: elephant grass, Andropogon species, etc., with long, wide, hairy leaves of a xerophytic appearance. Of the trees, oil palm 8-12 m should be noted heights, pandanus, butter tree, Bauhinia reticulata - evergreen tree with broad leaves. Baobab and various types of doum palm are often found. Along the river valleys, several kilometers wide, gallery forests, reminiscent of gilles, with many palm trees, stretch.

Grass savannas are gradually replaced by acacia ones. They are characterized by a continuous cover of cereals of lower height - from 1 to 1.5 m ; of the trees they are dominated by various types of acacias with a dense umbrella-shaped crown, for example the 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 in a loose, fleshy trunk.

In the grass savanna, where the rainy season lasts 8-9 months, cereals grow 2-3 m high, and sometimes up to 5 m: elephant grass (Pennisetum purpureum), bearded vulture with long hairy leaves, etc. Individual trees rise among the continuous sea of cereals : baobabs (Adansonia digitata), doom palms (Hyphaene thebaica), oil palms.

North of the equator, grass savannas extend to approximately 12°N latitude. In the southern hemisphere, the zone of savannas and woodlands is much wider, especially off the coast of the Indian Ocean, where it extends in some 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 woodlands with a predominance of representatives of the legume family (Brachystegia, Isoberlinia) occupied only the southern regions of their modern distribution. South of the equator, this plant formation is called the miombo woodland. The expansion of its range can be explained by its resistance to fires, high speed renewal. In eastern South Africa, open forests occur in combination with other types of vegetation well south of the tropics.

Under 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, spiny semi-savannas predominate. For most of the year, trees and shrubs in these areas remain without leaves; low grasses (Aristida, Panicum) often do not form a continuous cover; Among the cereals grow low up to 4 m heights, thorny trees (types of Acacia, Terminalia, etc.)

This community is also called the 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 spiny semi-savannas are replaced with distance from acacia savannas by the so-called thorny bush savanna. It reaches 18-19° south. sh., occupying most of the Kalahari.

2.3 Desertified savannas

In areas with a wet period lasting 2-3 months. typical savannas turn into thickets of thorny bushes and tough grasses with sparse turf. As the wet period decreases to 3-5 months. and a general decrease in precipitation, the grass cover becomes more sparse and stunted; the composition of tree species is dominated by various acacias, low, with a peculiar flat crown. Such plant communities, called desert savannas, form a relatively narrow strip in the northern hemisphere to the north of typical savannas. This strip expands from west to east in the direction of decreasing annual precipitation.

In deserted savannas, scanty rainfall is rare and occurs 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, also this natural area covers the Kalahari Basin. The vegetation here is represented by turf grasses, as well as thorny bushes and low leafless trees. In typical and desertified savannas, tropical red-brown soils are developed, not rich in humus, but with thick alluvial horizons. In places of development of basic rocks and lava covers - in the southeast of Sudan, in Mozambique, Tanzania and the Shari River basin - significant areas are occupied by black tropical soils, related to chernozems.

In such conditions, instead of a continuous herbaceous cover, only turf grasses and leafless and thorny shrubs are preserved. The belt of semi-deserts or deserted savannas on the Sudanese plains is called the “Sahel,” which in Arabic means “coast” or “edge.” This is truly the outskirts of green Africa, beyond which the Sahara begins.

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

Desertified 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. Desert savannas have a sparse grass cover, and thickets of thorny bushes (mainly acacias) are widespread in them.

Despite a number common features, savannas are characterized by significant diversity, which makes their division very difficult. There is a point of view that most of the savannas of Africa arose on the site of destroyed forests and only desertified savannas can be considered natural.

Chapter III. Environmental problems of African savannas

.1 The role of humans in the savanna ecosystem

Among the terrestrial biocenoses, the steppes produce the largest biomass of animals per unit surface, and therefore have long attracted humans, who lived primarily by hunting. This upright primate was created by nature itself to live in the steppes, and it was here, in the struggle for food and shelter, escaping from enemies, that it turned into an intelligent creature. However, as man improved, he increasingly complicated his weapons and invented new methods of hunting 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 controversial issue. There are various, very contradictory opinions on this matter. Some scientists believe that many inhabitants of the African savannahs and steppes were destroyed already in the Early Paleolithic, characterized by the use of hand axes (the so-called Acheulean culture). According to supporters of this opinion, the same thing happened in North America, when about 40 thousand years ago man first entered this continent through the Bering Land Bridge. At the end of the Ice Age, 26 genera of African and 35 genera of North American large mammals disappeared from the face of the Earth.

Supporters of the opposite point of view insist that ancient man, with his still extremely imperfect weapons, cannot be considered guilty of their destruction. Mammals that went extinct at the end of the Ice Age were most likely victims of global climate change, which affected the vegetation that served them as food or their prey.

It was established that when, much later, well-armed people appeared in Madagascar, whose fauna knew no natural enemies, this led to very sad consequences. In Madagascar, in a relatively short period of time, no less than 14 species of large lemurs, 4 species of giant ostriches were exterminated, and, in all likelihood, the same fate befell the aardvark and the pygmy hippopotamus.

However, it was only when the white man used firearms that this led to a catastrophic imbalance between him and the world of large animals. To date, in all corners of the Earth, people have almost completely destroyed the large animals of the savannas, turning the once endless grassy plains into arable land or pastures for livestock.

The destruction of the original vegetation 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 beings preserved, which was formed over millions of years. The man-hunter destroyed his steppe ancestral home and many animals generated by the amazing ecosystem of the savannah.

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

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

The nature of savannas has also changed significantly. Huge areas there are plowed and occupied by pastures. Due to overgrazing by cattle, sheep and camels, cutting down trees and shrubs, the savannas are increasingly turning into deserts. Especially negative consequences such land use in the north, where the savannah turns into 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 south by 200 km. and increased its area by thousands of square kilometers.

Forest shelterbelts are planted on the border with deserts, livestock grazing is limited in areas with sparse vegetation cover, and arid areas are irrigated. Major changes in natural complexes have occurred as a result of mining.

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

3.2 Economic role of savannas

Savannas play a very important role in human economic life. The climatic and soil conditions of savannas are favorable for tropical agriculture. Currently, large areas of savannas have been cleared and plowed. Significant areas are plowed here, grains, cotton, peanuts, jute, sugar cane and others are grown. In drier areas, livestock farming is developed. Some tree species growing in savannas are used by humans for their own purposes. Thus, teak wood produces hard, valuable wood that does not rot in water.

At present, we can say with complete confidence that a significant part of the wet and dry savannas of Africa arose as a result of human activity in the place of mixed forests, almost disappeared deciduous forests and woodlands. Since man learned to make fire, he began to use it for hunting, and later for clearing thickets for arable land and pastures. For thousands of years, farmers and herders set fire to the savannah before the rainy season to fertilize the soil with ashes. Arable lands, which were rapidly losing fertility, were abandoned after several years of use, and new areas were prepared for crops. In pasture areas, vegetation suffered not only from burning, but also from trampling, especially if the number of livestock exceeded the feeding “capacity” of pasture lands. Most of the trees were destroyed by fire. Mainly only a few tree species that have adapted to fires have survived, the so-called “fire lovers”, the trunk of which is protected by thick bark, charred only on the surface.

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

Fencing of private property, the construction of roads, prairie fires, the opening of large areas and the expansion of livestock farming have aggravated the plight of wild animals. Finally, the Europeans, unsuccessfully trying to fight the tsetse fly, staged a grandiose massacre, and more than 300 thousand elephants, giraffes, buffalos, zebras, wildebeest and other antelopes were shot from rifles and machine guns from cars. Many animals also died from plague brought with cattle.

3.3 Conservation actions to protect African savannas

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 across savannahs and not see a single large animal.

Once virgin forests are being developed by humans and are gradually uprooted to clear land, or cut down for the purpose of harvesting building materials. Further, the soil, which is no longer strengthened by plant roots and is not protected by tree crowns, is eroded during tropical rains, and was rich in the recent past natural landscape becomes impoverished, transforming into barren desert.

Often the interests of Africa's wild inhabitants conflict with the needs of local people, which makes wildlife conservation in Africa more difficult. In addition, environmental protection measures also require large expenses, and not every country’s government can afford to finance them.

However, some African states are concerned about the state of wild flora and fauna on their territory, so increased attention is paid to nature conservation. Wild animals are protected in the national parks of such countries, water bodies are subject to cleaning for fish breeding, and comprehensive measures are being taken to restore forests.

Governments of new independent states Africa, which has thrown off the yoke of colonialism, has strengthened and expanded the network of such reserves - the last refuges of wild animals. Only there can a person still admire the view of the primeval savannah. For this purpose, environmental protection areas are established - nature reserves and national parks. They protect the components of natural complexes (plants, animals, rocks etc.) and research work is underway. Nature reserves have a strict environmental regime, and national parks can be visited by tourists who are required to comply with established rules.

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

National natural park Serengeti- One of the largest and most famous in the world. Translated from the Maasai language, its name means vast plain. The park is located in East Africa. It is called an African paradise for animals. Its vastness is home to thousands of herds of large ungulates (various species of antelopes, zebras) and predators (lions, cheetahs, hyenas), which have been preserved in an untouched state 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. In this region of the savannah, buffalos, elephants, rhinoceroses, lions, leopards, cheetahs, giraffes, zebras, various antelopes, and among birds - marabou and secretary bird reign supreme. There are thousands of individuals of each animal species. Due to their diversity, the park is often compared to Noah's Ark.

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

U Rwenzori Parkprotected apes chimpanzees and gorillas.

The creation of nature reserves and national parks contributes to the conservation of rare plants, unique wildlife 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 diversity of species makes Africa a paradise for ecotourists.

Conclusion

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

Savannah is incredibly changeable and fickle. A dense forest may appear in this place in a few years. But there may be another development of events: all the trees will disappear, only grass will remain.

Life on the savannah is subject to the weather, which is very capricious here. Every year there is a dry, hot season. But no year is like the previous one.

The significance 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, provide the highest yield of plant products.

It's sad, but Africa's wildlife was once even more diverse. Currently, unfortunately, some species of wild flora and fauna have been completely destroyed, and some more are under threat of extermination.

A great misfortune for the inhabitants of the African savannahs are hunters who wipe out game species of animals to the ground. But no less problematic was the advance of civilization into the original natural habitats of African wild fauna. Traditional migration routes of wild animals are blocked by roads, and new human settlements are appearing 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 activity, but will also, to some extent, restore its impoverished animal and plant world, returning it to its former splendor and diversity .

List of sources

1. Boris Znachnov Radio Africa / Around the World No. 4, 2008 P. 84-92

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

Vlasova T.V. Physical geography continents and oceans: training manual for students higher ped. textbook establishments / T.V. Vlasova, M.A. Arshinova, T.A. Kovaleva. - M.: Publishing center "Academy", 2007. - 487 p.

Vladimir Korachantsev. Moscow. Armada-press, Africa - the land of paradoxes (Green series 2001. Around the world), 2001-413p.

Gusarov V.I. Exacerbation of environmental problems in Africa / Krajnavstvo. Geography. Tourism No. 29-32, 2007 P. 7-11

Kryazhimskaya N.B. Planet Earth. Equatorial and subequatorial belts M., 2001 - 368 p.

Mikhailov N.I. Physiographic zoning. M.: Moscow State University Publishing House, 1985.

Nikolay Balandinsky Pearl of Tanzania / Around the World No. 12, 2008 pp. 118-129

Yurkivsky V. M. Edges of the world: Dovid. - K.: Libid, 1999.

Http://ecology-portal.ru/publ/stati-raznoy-tematiki/geografiya/501524-afrikanskie-savanny.html

Http://www.ecosystema.ru/07referats/slovgeo/740.htm

Http://www.glossary.ru/cgi-bin/gl_sch2.cgi?RRgigttui:l!nut:

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During the dry season, most animals stop reproducing. Some groups, mainly invertebrates and amphibians, take refuge in shelters and hibernate during drought. Others stock up on food (ants, rodents), migrate (locusts, butterflies, birds, elephants and ungulates, predatory animals) or concentrate on small areas - survival stations (surroundings of water bodies, drying up riverbeds with nearby groundwater, etc.). p.).

Animals appear in large numbers and build substantial shelters. The most striking are the strong cone-shaped termite mounds, which can be more than 2 m high. The walls of these structures seem to be made of cement or baked clay, and they can hardly be broken through with a crowbar or pickaxe. The above-ground dome protects the numerous chambers and passages located below both from drying out in the hot season and from downpours in humid times. Termite passages reach deep into the aquiferous layers of the soil; during drought, a favorable humidity regime is maintained in the termite mound. Here the soil is enriched with nitrogen and ash plant nutrients. Therefore, trees often regenerate on destroyed and near residential termite mounds. Among vertebrate animals, 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 this food for future use.

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

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

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

Herbivores serve as food for numerous predators. In the savannas and semi-deserts of Africa there are lions, represented by two varieties: the Barbary, living north of the equator, and the Senegalese, common in the southern part of the continent. Lions prefer open spaces and almost never enter forests. Hyenas, jackals, leopards, cheetahs, caracals, and servals are common. There are several representatives of the civet family. In the lowland and mountain steppes and savannas there are many monkeys belonging to the group of baboons: real Raigo baboons, geladas, mandrills. Among the thin-bodied monkeys, the gverets are typical. Many of their species live only in cool mountain climates, as they cannot tolerate the high temperatures of the lowlands.

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

Birds are numerous in the savannas: African ostriches, guinea fowl, marabou, weavers, and the secretary bird, which feeds on snakes, is very interesting. Lapwings, herons, and pelicans nest near ponds.

The high mobility of animals makes the savanna highly productive. Wild ungulates are almost constantly on the move; they never graze pastures the way livestock do. Regular migrations, i.e. movements, of herbivores of the African savannah, covering hundreds of kilometers, allow vegetation to fully recover in a relatively short period of time. It is not surprising that in recent years the idea has emerged and strengthened that reasonable, scientifically based exploitation of wild ungulates promises greater prospects than traditional cattle breeding, which is primitive and unproductive. These issues are now being intensively developed in a number of African countries.

The giraffe is a decoration of the savannah, thanks to its graceful gait and amazing long neck. Translated from Latin, the name of the giraffe is translated as “camel-leopard,” apparently the discoverers considered it a cross between these animals. In addition to the long neck, the giraffe is also characterized by a tongue up to 45 cm long. These animals feed mainly on tree leaves; their growth allows them to reach the youngest and most delicious foliage. But drinking for a giraffe is completely uncomfortable; you have to spread and bend your legs. The long neck of the animal has the same number of cervical vertebrae as all mammals (7 pieces).

Elephants living in savannas are especially large; they are also called steppe or African elephants. They are distinguished by more powerful tusks and wide ears. Like ungulates, elephants heavily trample the plant surface of the savannah. The animals live in groups led by a large elephant. Thanks to their tusks, these heroes were on the verge of extinction a hundred years ago, but with the help of nature reserves this situation has returned to normal.

One cannot ignore the main predator of the savannah, the king of animals - the lion. Almost all inhabitants of the plains become its prey. Lions usually live in groups (prides), which include adult males and females, as well as their cubs. Responsibilities are very clearly distributed between members of the pride: lionesses are engaged in obtaining food, and large and strong males guard the territory.

The open plains of Africa are home to the cheetah, the fastest animal on Earth. While chasing its prey, it can reach speeds of up to 110 km/h. The special flying movements of the cheetah are explained by the peculiarities of its running, where the animal rests on only two paws. The cheetah is both strong and amazingly fast, which allows it to overtake prey such as antelope or zebra.

However, it is impossible to describe all the diversity of the savanna fauna. All this can be seen more clearly and colorfully in documentaries dedicated to the species richness of the fauna of this natural zone.

Nature film series - Savannah. Animal world

The spaces located in the subequatorial belt are covered with grass vegetation, as well as sparsely scattered trees and shrubs. Typical for subequatorial climate sharp divisions of the year into rainy periods and dry seasons are optimal conditions for the life of many animals. Many savannah areas are well suited for cattle breeding, but wild fauna have completely disappeared. However, there are still large national parks in the African savannah with animals that have adapted to survive in arid conditions.

Mammals

The fauna in the savannah is a unique phenomenon. Before the appearance of white colonizers in these territories, countless herds of large herbivores could be found here, making transitions in search of watering places. Such herds were followed by various predators, and then by typical carrion eaters. Today, the savannah is home to more than forty species of the largest mammals.

Giraffe

Thanks to its natural grace and impressive long neck, (Giraffidae) became a real ornament of the savannah, which its discoverers considered a cross between a leopard and a camel. The height of sexually mature adults varies, as a rule, between 5.5-6.1 m, a third of which is at the neck. In addition to the unusual neck, giraffes have a tongue, the length of which reaches 44-45 cm. The diet of this savannah animal consists mainly of succulent foliage of trees.

Savannah elephant

The largest one existing today terrestrial mammals, belonging to the genus of African elephants and the order Proboscidea. (Loxodonta africana) are distinguished by a heavy and very massive body, thick limbs, a large head located on a rather short neck, huge ears, as well as a muscular and long trunk, very unusual upper incisors, which turned into strong tusks in the process of evolution.

Caracal

Birds

The natural conditions of the savannah provide an ideal habitat for birds of prey, including hawks and buzzards. It is in the savannah that the largest of the existing modern feathered representatives of the fauna, the African ostrich, is found today.

African ostrich

A flightless ratite bird from the ostrich family and the order Ostrichidae has only two fingers on its lower limbs, which is exceptional in the class of birds. has expressive and rather large eyes, framed by very long eyelashes, as well as a chest callus. Adult individuals with a dense physique are distinguished by their height up to 250-270 cm, and are characterized by a very impressive weight, often reaching 150-160 kg.

Weavers

Weavers (Ploceidae) are representatives of the family of birds from the order Passeriformes. Adult small birds are distinguished by a rounded and relatively large head. Some weavers have a characteristic crest in the crown area. The bird's beak is conical and short, rather sharp. There are three longitudinal ridges on the palate, connecting at the back. The wings are short, rounded, and males differ from females in the size and sometimes color of their plumage.

Guinea fowl

The only species of the genus Numida has been domesticated by humans. Such savannah birds are distinguished by the presence of a horn-like process in the crown area and a fleshy red beard. The bird is characterized by a slightly hooked and laterally compressed beak of moderate size, as well as the presence of rounded wings and a short tail covered with covert feathers. The plumage is uniform, dark gray, with white rounded spots with a dark border.

Secretary Bird

Reptiles and amphibians

Savannas and semi-desert areas are home to many reptiles and amphibians. The biotope is very characteristic of the tropics with elevated landscapes and arid climatic conditions. Reptiles, amphibians and reptiles serve as the main food for many savannah terrestrial and avian predators. There are few amphibians in the nature of the savanna, there are no newts and salamanders, but toads and frogs, turtles and lizards live. The most numerous among reptiles are snakes.

Varan Komodo

Fish

Savannahs are located on three different continents, and water resources These territories are very rich and have a huge food supply, so the world of the inhabitants of savannah reservoirs is very multifaceted. Aquatic inhabitants are common in South America, Australia and India, but the most diverse fish world is in the rivers and lakes of the African savanna.

Tetraodon miurus

The Congo River dweller (Tetraodon miurus) belongs to the relatively large family of pufferfish, or four-toothed fish. Predatory and aggressive aquatic representatives prefer to stay in the lower or middle water layers. The head is large, occupying about a third of the total body length. The body has a bizarre pattern in the form of spots of black or dark brown.

Fahaki

The African rocktooth (Tetraodon lineatus) belongs to the category of brackish-water and freshwater ray-finned fish from the pufferfish family and the order pufferfish. Fahaki are distinguished by their ability to inflate into a large air bag, acquiring a spherical shape. The body length of an adult is 41-43 cm, with a weight within one kilogram.

Neolebias

African Neolebias appearance resembles a small tench. The small mouth located at the end of the snout has no teeth. The dorsal fin is rectangular in shape, and the caudal fin is strongly carved. The main color of males is brownish-red, the back is olive-brown, and the underparts are yellowish. Adult females are characterized by less pronounced and not too bright coloring.

Parrotfish

Scaridae, or parrotfish (Scaridae) are representatives of the family of ray-finned fish, distinguished by different morphological characteristics and, as a rule, having very bright and beautiful colors. to his unusual name such aquatic inhabitants owe a kind of “beak”, represented by numerous teeth, densely located on the outer part of the jaw bone. Some species are characterized by the presence of external canines or incisors.

Handsome chromis

A very bright and unusual cichlid (Hemichromis bimaculatus) has an elongated and tall body with flat sides. Females are more brightly colored than males, and the main color tone is grayish-brown. The body has three rounded dark spots, and on the gill covers there are noticeable longitudinal bluish rows of sparkling dots.

Elephant fish

The Nile elephant (Gnathonemus petersii) has an unusual body structure, elongated and noticeably compressed on the sides. The pelvic fins are absent, and the pectoral fins are raised quite high. The symmetrical anal and dorsal fins are located almost at the very base of the forked tail. The area where the caudal fin connects to the body is quite thin. The lower lip in the shape of a proboscis gives the fish an external resemblance to an ordinary elephant.

Electric catfish

A bottom-dwelling freshwater fish (Malapterurus electricus) has an elongated body and six antennae in the head area. Small eyes that glow in the dark. The coloring is quite variegated: dark brown back, yellow belly and brownish sides. There are numerous dark spots on the body. The ventral and pectoral fins of the fish are pink, and the caudal fin is characterized by a dark base and the presence of a wide red edge.