A woody plant of African savannas that stores moisture. Animals and plants of the savannah

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, 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. Leguminous plants, vetches, daisies and small flowers hide among the tall grasses.

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 of rare species of 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 the geographical location of African savannas.

2. Study the flora and fauna of savannas.

3. Consider the features of different types of African savannas.

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

General characteristics of African savannas

Geographical location and climatic features of African savannas

Savanna 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 at invariably high air temperatures (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.

Vast areas 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 the 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, tropical rainforest is limited only to river valleys, and at 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.

The savannah zone from northern Kenya to the sea coast of 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. The monsoon winds, which bring seasonal rains, significantly influence the climate of the savannas. Because 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 savannas 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 in Australia - bottle trees and eucalyptus trees. 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.

The dense and tall grass cover provides abundant food for the largest animals, such as elephants, giraffes, rhinoceroses, hippos, zebras, antelopes, which in turn attract large predators such as lions, hyenas and others. The savannas are home to the largest 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.

In parallel with 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

Unfortunately, not many people know what savannas are and where they are located. Savannas are a natural area that is found mainly in the subtropics and tropics. The most important feature of this strip is the humid seasonal climate with pronounced alternations between dry and rainy seasons. This feature determines the seasonal rhythm of natural processes here. This zone is also characterized by ferrallitic soils and herbaceous vegetation with groups of isolated trees.

Savannah localization

Let's take a closer look at what savannas are and where they are located. The largest shroud zone is in Africa, it occupies about 40% of the area of ​​this continent. Smaller areas of this natural zone are located in South America (on the Brazilian plateau, where they are called campos, and in the Orinoco River valley - llanos), in the east and north of Asia, the Deccan Plateau, the Indo-Gangsai Plain), as well as in Australia.

Climate

The savannah is characterized by monsoon-trade wind circulation of air masses. In summer, these regions are dominated by dry tropical air, and in winter by equatorial humid air. The farther away you go, the more there is a reduction in the rainy season (from 8-9 months to 2-3 on the outer borders of this zone). The amount of annual precipitation decreases in the same direction (from approximately 2000 mm to 250 mm). Savannah is also characterized by slight temperature fluctuations depending on the season (from 15C to 32C). Daily amplitudes can be more significant and reach 25 degrees. Such climatic features have created a unique natural environment in the savannah.

Soils

The soils of the region depend on the duration of the rainy season and differ in leaching regime. Ferrallitic soils have formed near areas where the rainy season lasts about 8 months. In areas where this season is less than 6 months, you can see red-brown soils. On the borders with semi-deserts, the soils are unproductive and contain a thin layer of humus.

Savannahs of South America

In the Brazilian Highlands, these zones are located mainly in its interior areas. They also occupy areas and In Brazil there are typical savannas with red ferrallite soils. The vegetation of the zone is predominantly herbaceous and consists of the legume, grass, and asteraceae families. Tree species of vegetation are either not present at all, or are found in the form of separate species of mimosa with an umbrella-like crown, milkweeds, succulents, xerophytes and tree-like cacti.

In the northeast of the Brazilian Highlands, most of the area is occupied by caatinga (a sparse forest of drought-resistant shrubs and trees on red-brown soils). The branches and trunks of caatinga trees are often covered with epiphytic plants and vines. Several types of palm trees are also found.

The savannas of South America are also located in the arid regions of the Gran Chaco on red-brown soils. Sparse forests and thickets of thorny bushes are common here. The forests also contain algarrobo, a tree from the mimosa family, which has a curved column and a highly branched, spreading crown. Low forest tiers are shrubs that form impenetrable thickets.

Among the animals in the savannah are the armadillo, ocelot, Pampas deer, Magellan cat, beaver, Pampas cat, rhea and others. Of the rodents, the tuco-tuco and viscacha live here. Many areas of the savanna suffer from locust infestations. There are also many snakes and lizards here. Another characteristic feature of the landscape is a large number of termite mounds.

African shrouds

Now all readers are probably wondering: “Where is the savanna in Africa?” We answer that on the black continent this zone practically follows the contour of the tropical rainforest region. In the border zone, forests are gradually thinning out and becoming poorer. Among the forest areas there are patches of savannas. Tropical rain forest is gradually limited to river valleys, and in the watershed areas they are replaced by forests, the trees of which shed their leaves in dry times, or savannas. There is an opinion that tall grass tropical savannas began to form in connection with human activity, as he burned out all the vegetation during the dry season.

In areas with a short wet season, the grass cover becomes shorter and sparse. Among the tree species in the region, there are various acacias with a flat crown. These areas are called dry or typical savannas. In regions with a longer rainy season, thickets of thorny bushes grow, as well as tough grasses. Such vegetation areas are called desert savannas; they form a small strip in

The African savannah world is represented by the following animals: zebras, giraffes, antelopes, rhinoceroses, elephants, leopards, hyenas, lions and others.

Savannahs of Australia

Let's continue our topic “What are savannas and where are they located” by moving to Australia. Here this natural zone is located mainly north of 20 degrees south latitude. In the east there are typical savannas (they also occupy the south of the island of New Guinea). During the wet season, this region is covered with beautiful flowering plants: the families of orchids, ranunculaceae, lilies and various grasses. Typical trees are acacias, eucalyptus, casuarina. Trees with thickened trunks, where moisture accumulates, are quite common. They are, in particular, represented by the so-called bottle trees. It is the presence of these unique plants that makes the Australian savanna a little different from the savannas that are located on other continents.

This zone is combined with sparse forests, which are represented by different types of eucalyptus. Eucalyptus forests occupy most of the country's northern coast and a large part of Cape York Island. In the Australian savannah you can find many marsupial rodents: moles, rats, wombats, and anteaters. The echidna lives in the bushes. The emu, a variety of lizards and snakes can also be seen in these regions.

The role of savannas for humans

After we have found out in detail what savannas are and where they are located, it is worth saying that these natural areas play an important role for humans. Peanuts, grains, jute, and cotton are grown in these regions. Livestock farming is quite developed in arid areas. It is also worth noting that some tree species growing in this region are considered very valuable (for example,

Despite its greater importance, people, unfortunately, continue to systematically destroy the savanna. Thus, in South America, many trees die as a result of burning fields. Large areas of savannah are cleared of forest from time to time. Until recently, in Australia, about 4,800 square meters were cleared annually to provide livestock pasture. km of forest. Such events are now suspended. Many exotic trees (Nile acacia, vaulting landata, prickly pear and others) also have a detrimental effect on the savannah ecosystem.

Climate change leads to changes in the function and structure of the savanna. Woody plants are suffering greatly as a result of global warming. I would like to believe that people will start

Savannah represents one of the most popular landscapes on the African continent. Moreover, savanna 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 savannas have to adapt to difficult climatic conditions.

Characteristics of the savannah

Its features are as follows:

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

Savannah grasses

Herbs of the savannah plant world mostly tough-skinned grasses, there are also perennials, and during rainy periods, when the area is subject to flooding, even sedges grow here. Lichens and mosses are very rare and can only be seen on rocks.

Of the cereals that are most characteristic of this African landscape, elephant grass. The plant got its name because it is a favorite delicacy of giant elephants. During the rainy season, this grass can grow up to 3 meters in height, and in dry times, the ground shoots dry out and often die from fires. But due to the fact that the root system remains alive, elephant grass grows back in wetter conditions. Local residents often use the shoots of this plant for food.

Bermuda grass (Pigmatum grass) forms a dense carpet, grows in open areas, constantly exposed to threats - floods, animal grazing, fires. However, the plant has adapted well to surviving 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 than not, savannah trees are stunted and are often entwined with vines.

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

The flowering period takes several months, but the life of each flower is fleeting, just a single night. The plant is pollinated by bats. The thick trunk protects the plant from fires, which are not uncommon in the savanna, and is also capable of retaining moisture accumulated during the rainy season for a long time, like a sponge. The length of the roots of this tree often reaches 10 meters.

Man widely uses baobab in his activities, eating leaves, making paper, fabric 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 savannah plant world, it has a long lifespan, from 80 to 100 years, palm wine is made from its juice, and the pericarp pulp is used in the production of soap.

Mongongo. This is a plant of the Euphorbiaceae family, reaching a height of 30 m. It has palmate leaves and flowers collected in inflorescences. The fruits are actively consumed by indigenous people. This tree can live in the savanna due 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, which is why it is often called umbrella-shaped. Thanks to such a flat and wide crown of the acacia, it creates shade under which herbs grow, hiding from the scorching sun. Acacia Senegalese – a small tree, a representative of the legume family, it reaches a height of no more than 6 m, with a trunk diameter of about 30 cm. This acacia has thorns. The benefits of the tree are great: by accumulating nitrogen, like other legumes, Senegalese acacia enriches poor soils, and its pods and leaves are absorbed by the fauna of the savannah.

Twisted acacia withstands both heat and drought well. Its wood has found application in furniture production and construction.

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

Persimmon medlar- a representative of the African savanna, this is a plant from the Ebony family, a deciduous tree, the bark of which is colored 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, blooms with cream flowers during the rainy season, fruits appear only on female trees, they gradually ripen, changing color from light yellow to purple.

Combretum red-leaved grows near rivers, the average tree height 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 alone, less often - in small groups. In the savannas of Brazil you can often find real forests, although they are rare. The herbaceous and semi-shrub cover here is about a meter.

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

The second is typical for cacti formation - savannas - spaces covered with grassy vegetation with trees standing far from each other. Savannas are characterized by a long period of drought. For example, in South American savannas it falls in winter (June-August). At this time, there is little precipitation (120 mm), it is relatively cold (average temperature in August 15°), and the plants enter a dormant period. Summer, on the contrary, is humid (precipitation in January is 400 mm) and hot (the average temperature in February is 34°).

Cacti are found mainly in Venezuelan and Brazilian-Uruguayan savannas, which are characterized by an almost complete absence of trees. Cereus, prickly pear, and perescia grow here along with cereals, bromeliads, asteraceae, and legumes. The savannas include the very unique and cacti-rich Gran Chaco plain, located in Paraguay and Argentina between 18 and 24° S. w.

The savannas of North America are characterized by rare but abundant summer rains. Winter is a dry season. The temperature of the coldest month varies over a wide range from -2 to -22°, and the warmest month - from +22 to +34°. Subtropical cactus-acacia and tropical Mexican savannas are especially rich in cacti. In vast areas covered with mesquite grass (species of the genus Hilaria), entire thickets are often formed by Lindheimer's prickly pear ( O. lindheimeri) and neobuxbaumia mescal ( Neobuxbaumia mezcalaensis).

Probably not everyone knows that cacti also grow in tropical evergreen rain forests, where 2000-3000 mm of precipitation falls throughout the year, where the air, filled with moisture, is never colder than 18°. Cacti that grow in tropical forests, such as the Amazon, are not like their spiny relatives from the deserts of Argentina or Peru. They, as a rule, do not have thorns, their stems are often flat and not so juicy. They do not live on earth. These are the so-called epiphytic cacti, living on the trunks and branches of trees: rhipsalis, hatiora, epiphyllum, schlumbergera, wittia amazonica ( Wittia amazonica) etc. Life in a humid climate greatly changed their appearance. But they weren't always like this; their distant ancestors were inhabitants of arid climates. As if “remembering” this, the plants, during their development, first produce spiny stems, similar to the Cereus cactus.

We have characterized only the main types of vegetation: deserts, savannas, tropical forests, which are more or less characterized by cacti. It is also interesting to note the presence of cacti in pine-juniper forests and on tropical sea coasts, in the so-called mangrove thickets. Mangroves are vegetation periodically flooded with salty sea water. In northern Venezuela, for example, on the inner edge of the mangroves, prickly pears and cereus grow on small sandy mounds. The salt in the sand is washed away during rains into the deeper layers of the soil and thus does not interfere with the growth of cacti.

Already this far from complete overview of the ecological and geographical distribution of cacti gives an idea of ​​the extremely diverse conditions of their habitat. The soils on which they grow are also varied - sandy, rocky, calcareous, granite, volcanic and clayey. When growing cacti, it is impossible to accurately reproduce their natural habitat conditions. The cultivator’s task is to study the plants and bring the conditions of their culture closer to natural living conditions.

Cacti occupy a large place in the life of the peoples of Mexico and South America. Prickly pears are of particular importance. The entire history of Mexico is connected with them: It is not for nothing that the image of prickly pear is included in the national emblem of this country. An old Mexican legend tells how one day the Aztec tribes, tired of wandering through the mountains, stopped on the shores of Lake Texcoco. On a small island they saw an eagle sitting on a prickly pear and tearing apart a snake. This was considered a good omen. The tribes descended from the mountains and founded the city of Tenochtitlan (“place of the sacred prickly pear”) here, on the site of which Mexico City, the capital of Mexico, is now located.

The sweet and sour fruit of Teonochtli, or tuna, as the Aztecs called prickly pear, provided them with food. Later, Europeans began to call it prickly pear. The shape of prickly pear fruits resembles a small lemon or pear. They can be eaten fresh, dried or boiled, after removing the thin spines from the skin. The fruits contain albumin, plant mucilage, and sugars. The juice obtained from prickly pear fruit is used for syrups, jellies, and as a red coloring agent in the confectionery industry. As a result of fermentation of the juice, the drink Kolinke is obtained.

To this day, Mexicans also use prickly pear stems for food: young shoots, cleared of thorns, are used to prepare national dishes. However, prickly pears can also cause great harm to humans. Their exceptional ability to reproduce with easily broken stems makes them a threat to pastures. A striking example of this is the sad experience of Australia, where its accidental introduction in 1787 led to the fact that the best pasture lands were filled for 150 years with virtually only one prickly pear. Despite the abundance of succulent green food, the animals refused it. The reason for this is the spines and glochidia that densely cover the stems of prickly pears. Neither mechanical cutting nor the use of pesticides gave positive results. Only the discovery of biological control methods saved the situation. In 1925, the Argentine moth Cactoblastis cactorum, which feeds on prickly pears, was specially brought to Australia. This struggle continued for about 8 years. Having found unlimited supplies of food, the moth began to multiply intensively and “ate” all the growths.

The fruits of many other cacti are widely used in the life of Mexicans. The most delicious of them are the fruits of Echinocereus ( Echinocereus). They are eaten raw, steamed, and dried. From the fruits of Pilosodereus ( Pilosecereus piauhyensis) prepare marmalades and sweets. The fruits of myrtillocactus taste like blueberries, disocactus - raspberries, and prickly pear ( Opuntia leucotricha) - peach. Mexicans love and appreciate cacti. It is not for nothing that the inhabitants of the state of Oaxaca call Myrtillocactus croupiaoareola, ( M. grandiareolatus) "our father" - padre nuestro. The spiny fruits of Pachycereus Printa and Pachycereus "native comb" replace brushes and combs for local residents.

Cactus stems are also widely used on the farm. Thus, from Helianthocereus pasacanensis ( Helianthocereus pasacana) make light, durable furniture, window frames, doors, roofs. Many cereus are used as hedges. Plant “belts” are made from ferocactus Wislicen as souvenirs; To do this, the stem pulp is cut into long strips and treated with glycerin. In the confectionery industry, the succulent stems of this cactus and Melocactus Oaxaca ( M. oaxacensis) are used to prepare candied fruits, marmalades and sweets. Local residents of Argentina use the juicy stem and root of Achakana - Neoverdermania Vorwerk, which tastes like potatoes, as food.

Until recently, cochineal cacti were of great importance ( Opuntia ficusindica var. splendida, Opuntia hernandezii, Nopalea cochenillifera). Aphids - cochineal - were bred on their stems ( Dactylopius coccus). The wingless female cochineal reproduces quickly, which allows insects to be collected 2-3 times a year. The cochineal is carefully peeled from the prickly pear stems into bags, immersed in boiling water, and then dried. Dry insects make excellent scarlet dye for cloth and silk, which is also used as food dye for coloring butter and cheese. The production of cochineal, which originally arose in Mexico and Peru, has spread widely throughout tropical America, Spain, Algeria, India, and Australia. It took on a particularly large scale in the Canary Islands. With the use of aniline dyes, the production of cochineal decreased, but even now it is highly valued and used for the manufacture of artistic paints.

One of the secrets of the unfading colors on the pottery of ancient Peruvian craftsmen is that immediately after production they are filled with cactus juice.

Since ancient times, cacti have been used as medicinal plants. The Indians used the dried and crushed stems of the “soldering tree” (prickly pear species) as a plaster. The fruits of many prickly pears have a diuretic effect. Selenicereus stem juice ( Selenicereus) were used externally for rheumatism, and an alcoholic or aqueous extract of the petals and stems of Selenicereus grandiflora ( Selenicereus grandfflorus) and is currently used in medicine as a remedy for cardiovascular diseases. The medicinal properties of cacti are explained by the alkaloids they contain, which have so far been found in a small number of species. Among them is the cracked roseocactus ( Roseocactus fissuratus), trichocereus whitish ( Trichocerews candicans), Lophocereus species, epithelanths and some others.

The most famous alkaloid-bearing cactus has long been considered peyote, or lophophora ( Lophophora williamsii). In ancient Mexico, where a number of cacti were deified, peyote was also elevated to the rank of a sacred plant. Indian tribes found the most interesting uses for lophophore: some used it for snake and scorpion bites, others for pneumonia and tuberculosis, and others used it to stop bleeding. But the main thing remains the use of peyote as a ritual remedy. The bitter juice of the stem and root of peyote contains alkaloids mescaline, lophophorine, peyotine, etc., which cause auditory and visual color hallucinations. The Huichol tribe, living in remote areas of the Sierra Madre Occidental, still makes an annual pilgrimage in search of peyote. Lophophora collectors - peyoteros, gathering in groups of about ten people, go in search of the sacred plant. With a basket of meager food and religious objects on their backs, they steadfastly endure all hardships and hardships. After several weeks or even months, the peyoteros return home. Ritual ceremonies begin, during which pieces of peyote are eaten raw or added to a drink made from agave. Missionaries, trying in every possible way to eradicate the ancient religion of the Aztecs, banned the use of peyote. In California, keeping lophophora even in a collection is punishable by law.

During the dry season, cacti come to the aid of animals. Carefully knocking down the thorns with their hooves, they suck out the moisture accumulated by the plant inside the stem.

The issue of food supply is important for arid areas. This problem is also relevant for desert and semi-desert zones of the USSR. In this regard, the possibility of using frost-resistant prickly pears as livestock feed is being studied. Chemical analysis of straight prickly pear ( Opuntia stricta var. kossi), conducted at the Main Botanical Garden in Moscow, shows that the green mass of prickly pears includes starch, sucrose, protein, a small amount of vitamin C and about 85% water. However, the use of such succulent food is complicated by the presence of a large number of thin spines - glochidia - on the stems. Their digestibility in the walls of the stomach of animals is only 32%. Enormous work towards the creation of glochidia-free forms was carried out by the American breeder Luther Burbank. He devoted more than 16 years of his life to this noble goal. Unfortunately, Burbank’s titanic work was not appreciated in the USA, and the thornless form of prickly pear was consigned to oblivion.

Finally, it is necessary to note the great aesthetic and educational significance of cacti. Both in their homeland and far beyond its borders, cacti have earned well-deserved love as ornamental plants.

Savannas and deserts are huge areas of our planet, sharply different from each other in flora and fauna and similar only in their hot climate. Zones of equatorial forests on Earth give way to savannas, which turn into semi-deserts, and then semi-deserts give way to deserts - with quicksand and a minimum of vegetation. These territories are of great interest to researchers; many expeditions are sent there every year to study the natural diversity of our planet. What are savannas and deserts and how they differ from temperate steppes, you will learn on this page

What are savannas and what plants grow in them?

Savannas are grassy plains located between tropical forests and deserts. They differ from the temperate steppes in that trees and shrubs are found everywhere, sometimes solitary, and sometimes forming entire groves. So savanna can also be called forest-steppe. Acacias, baobabs and cereals grow there. There are savannas in America, where they are called “llanos,” and in Africa and Asia.

The main feature of savannas is that there are clearly distinct rainy and dry seasons.

As you can see in the photo, savannas look completely different in different seasons. Both plants and animals have adapted to months-long droughts. The leaves of savanna plants are usually narrow, they can curl into a tube, and are sometimes covered with a waxy coating. During the dry season, vegetation freezes, and numerous animals - zebras, buffaloes, elephants - make long migrations (transitions from one place to another) in search of water and food. In the rainy season, on the contrary, the savannah is full of life.

Euphorbia candelabra grows only in Somalia and eastern Ethiopia. Its branches resemble a candelabra, that is, a candlestick for several candles. The tree reaches a height of 10 m, and even elephants find refuge in its shade.

When talking about what grows in the savannah, one cannot fail to mention the favorite delicacy of giraffes - acacia. These trees have a wide, flat crown that creates shade for the leaves growing below, protecting them from drying out. These are quite tall trees, and their leaves and branches serve as food for the inhabitants of those places. Giraffes are very fond of acacia - the tallest land animals on our planet. With a height of 6 m, a third of which is the neck, the giraffe finds plant food at a height where it has no competitors. And its long 45-meter tongue allows it to grab the farthest branches.

Perennial savannah grasses have underground shoots and the roots grow to form a woody, tuberous body. It persists through the dry season and produces new shoots as soon as wet weather sets in.

Interesting facts about deserts and desert plants

Deserts occupy almost a fifth of the land. All of them, except the Arctic and Antarctic, arise in a hot, dry climate. Not all desert lands are bare and dull. There are also xerophytic plants, the roots, stems and flowers of which are able to obtain and store water, hide from the merciless sun and capture its life-giving rays. And some of them - ephemerals - grow, bloom and fade in just a few weeks under favorable conditions for life.

The desert plant saxaul can be a shrub or a small tree. Its roots go 10-11 m into the ground. These plants form desert-woody thickets - saxaul forests.

Tamarisk grows along river banks, but also lives in deserts, salt marshes and sand. This plant is widely used for fixing shifting sands in forest plantations and in desert and semi-desert areas, especially on saline soils.

Camel thorn is a thorny subshrub. It is helped to successfully exist in the sand by a long root system that goes to a depth of 3-4 m, where water is located. And the plant itself rises above the ground by no more than 1 m.

Ephedra is found in dry areas throughout the world. Its leaves are small and scale-like, which reduces water loss, and its roots are strong and long. This is a poisonous plant, but medicines for asthma and other diseases have been made from it for several thousand years.

One of the most interesting facts about deserts is the presence of magnificent oases in these seemingly dead territories. An oasis in the desert is a place where underground water comes to the surface and forms a spring or lake. Birds fly there to drink, and they spread seeds, from which trees, herbs and shrubs later grow. As long as there is water, the oasis lives. It could be a small pond with a few palm trees or an entire city with rich agricultural land. This is how life flourishes among the sands.

Deserts are not only sandy, but also rocky, rocky, and saline. Their vegetation serves as food for animals, even such large ones as camels. They feed on branches and leaves of saxaul and desert acacia, although the leaves of these plants are small and hard. The main delicacy of the “ship of the desert” is camel thorn. Its branches are prickly and inedible, but the leaves are very juicy and tasty.

Desert cacti plants and their photos

Among the plants of southern deserts and semi-deserts, cacti stand out. They do not have leaves, but they have a thick stem in which reserves of water and nutrients are created. Such plants are called "succulents". Desert cacti are very diverse: among them there are large ones like trees, medium ones like shrubs, and short ones like herbs.

Cacti are native to North and South America, and can be found from Canada to Patagonia. Therefore, cacti are a sign of American deserts and semi-deserts. Cacti in the desert differ from other succulents in that they have areoles, that is, modified buds with scales that have turned into spines and hairs or only spines.

Pay attention to the photo: cacti in the desert sometimes form real cactus thickets, which are not so easy to get through. In Australia they even erected a moth monument. The fact is that there, in the 1920s, a South American cactus catastrophically multiplied, and only a compatriot moth could cope with it.

The desert plant saguaro cactus, or giant carnegia, reaches a height of 1.5 m by the age of 20. But it continues to grow, and cacti 7-8 m high have side shoots that look like hands. The cactus has nowhere to rush, since its average lifespan is 75 years, but there are also 150-year-old centenarians. They grow up to 15-20 m, weigh about 10 tons, and 90% of their weight is water. The saguaro has short roots, but very tenacious, so it is not afraid of any hurricanes.

On the Galapagos Islands, off the coast of South America, you can see tree-like cacti reaching a height of 12 m. Surprisingly, these trees are cacti. These are prickly pears, which most often grow as shrubs on the mainland.