Savannahs and woodlands. Presentation on the topic "savannas and woodlands" What animals are in savannas and woodlands
Amazon river
largest river of South America - Amazon. Most of its basin lies south of the equator. Square of this most extensive river basin in the world over 7 million km2, length river from the main source (Marañon River) is 6400 km. If, however, Ucayali and Apurimac are taken as the source of the Amazon, then its length reaches 7194 km, which exceeds the length of the Nile. Water consumption The Amazon is several times the flow of all the largest rivers in the world. It is equal to an average of 220 thousand m3/s (the maximum flow rate may exceed 300 thousand m3/s). Average annual flow The Amazon in the lower reaches (7000 km3) makes up the majority of the flow of all of South America and 15% of the flow of all the rivers of the Earth!
Main source The Amazons - the Marañon River - begins in the Andes at an altitude of 4840 m. Only after the confluence with the first major tributary - the Ucayali - within the plain, the river receives the name Amazon.
Amazon collects its numerous tributaries(more than 500) from the slopes of the Andes, the Brazilian and Guiana highlands. Many of them are over 1500 km long. The most numerous and largest tributaries of the Amazon are the rivers of the southern hemisphere. The largest left tributary is the Rio Negro (2300 km), the largest right and largest tributary of the Amazon is Madeira (3200 km).
Part of the tributaries, eroding clayey rocks, carry very muddy water (“white” rivers), others, with clear water, are dark from dissolved organic substances (“black” rivers). After falling into the Amazon Rio Negro (Black River), light and dark waters flow in parallel, without mixing, for about 20-30 km, which is clearly visible on satellite images.
Channel width The Amazon after the confluence of Maranyon and Ucayali is 1-2 km, but downstream it increases rapidly. At Manaus (1690 km from the mouth) it reaches already up to 5 km, expands in the lower reaches up to 20 km, and at the mouth the width of the main channel of the Amazon, together with numerous islands during the flood, reaches 80 km. In the western part of the lowland, the Amazon flows almost at the level of the banks, in fact, without a formed valley. To the east, the river forms a deeply incised valley which contrasts sharply with the watershed.
Approximately 350 km from the Atlantic Ocean begins amazon delta. Despite its ancient age, it did not move into the ocean beyond the boundaries of the native shores. Although the river carries out huge masses of solid material (an average of 1 billion tons per year), the process of delta growth is hindered by the activity of the tides, the influence of currents, and the lowering of the coast.
In the lower reaches of the Amazon, a great influence on its regime and the formation of shores is exerted by ebbs and flows. The tidal wave penetrates more than 1000 km upstream, in the lower reaches its wall reaches a height of 1.5-5 m. The wave rushes against the current at great speed, causing strong excitement on sandbars and banks, destroying the coast. Among the local population, this phenomenon is known under the name of "pororoka" and "amazunu".
The Amazon is full of water throughout the year. Twice a year river water level rises to a considerable height. These maxima are associated with rainy periods in the northern and southern hemispheres. The greatest flow in the Amazon occurs after the rainy season in the southern hemisphere (in May), when the bulk of the water is carried by its right tributaries. The river overflows its banks and in the middle reaches fills a huge territory, creating a kind of giant inland lake. The water level rises by 12-15m, and in the Manaus region, the width of the river can reach 35 km. Then comes a period of gradual decrease in water flow, the river enters the banks. The lowest water level in the river is in August and September, then there is a second maximum associated with the summer rains of the northern hemisphere. On the Amazon, it appears with some delay, around November. The November maximum is significantly inferior to the May one. In the lower reaches of the river, two maxima gradually merge into one.
From the mouth to the city of Manaus, the Amazon is accessible to large courts. Vessels with a fairly deep draft can penetrate even as far as Iquitos (Peru). But in the lower reaches, due to the tides, the abundance of sediment and islands, navigation is difficult. Deeper and accessible to ocean vessels is the southern branch - Para, which has a common mouth with the Tocantins River. On it stands a large ocean port of Brazil - Belen. But this branch of the Amazon is now connected with the main channel only by small channels. The Amazon with tributaries is a system of waterways with a total length of up to 25 thousand km. The transport value of the river is great. For a long time, it was the only route connecting the interior of the Amazonian lowland with the Atlantic coast.
The rivers of the Amazon basin have large water energy reserves. Many tributaries of the Amazon, when entering the lowlands, cross the steep edges of the Brazilian and Guiana highlands, forming large waterfalls. But these water resources are still very poorly used.
Parana and Uruguay rivers
The second largest river system in South America includes the Parana River with Paraguay and Uruguay, which have a common mouth. its name ( La Platskaya) the system received from the eponymous giant estuary of Parana and Uruguay, reaching 320 km in length and 220 km in width at the mouth. The basin area of the entire system is more than 4 million km2, and the length of the Parana, according to various sources, ranges from 3300 to 4700 km. The sources of Parana - Rio Grande and Paranaiba - are located in the Brazilian Highlands. Many other rivers of the system also begin there. All of them in the upper reaches are full of rapids and form several large waterfalls. The largest waterfalls are Guaira 40 m high and 4800 m wide on the Paran and Iguazu 72 m high on its tributary of the same name. They have a network of hydroelectric stations.
In the lower reaches of the Parana - a typical lowland river. Main maximum discharge occurs in May due to summer rains in the Brazilian Highlands. shipping the importance of the rivers of the La Plata system and La Plata itself is very great.
Orinoco river
The third largest river in South America is the Orinoco. Its length is 2730 km, the basin area is over 1 million km2. The Orinoco originates in the Guiana Highlands. Its source was discovered and investigated by a French expedition only in 1954. The Casiquiare Orinoco River connects with the Rio Negro, a tributary of the Amazon, where part of the water of the upper Orinoco flows. This is one of the most significant examples of river bifurcation on Earth. When it flows into the Atlantic Ocean, the river forms a large delta, the length of which reaches 200 km.
The water level in the Orinoco depends entirely on the rainfall that falls in the northern part of its basin in the summer (from May to September). The maximum for Orinoco, falling on September-October, is expressed very sharply. The difference between summer and winter water levels reaches 15 m.
On the Guiana Plateau, in Venezuela, in the upper reaches of the Churun River (basin of the Caroni River, a tributary of the Amazon) is highest waterfall in the world- Angel.
lakes
There are few lakes in South America. The main genetic groups of lakes on the mainland are tectonic, glacial, volcanic, lagoonal. There are small glacial and volcanic lakes in different parts of the Andes. The largest glacial and glacial-tectonic lakes are concentrated in the west of the Southern Andes.
The largest lake on the continent Titicaca- located on the Andean plateau at an altitude of more than 3800 m, on the border between Peru and Bolivia. Its area is 8300 km2, and the maximum depth is 281 m. Terraces are pronounced on the shores of the lake, indicating a repeated decrease in its level. The lake has a drain into another, shallower tectonic lake - Poopo. The water in Lake Titicaca is fresh, while in Poopó it is highly saline.
On the internal plateaus of the Andes and on the plain of the Gran Chaco, there are many lakes of tectonic origin, shallow, endorheic and saline. In addition, saline marshes and salt marshes (“salares”) are common.
Along the low-lying shores of the Atlantic Ocean and the Caribbean Sea there are large lagoon lakes. The largest of these lagoons is located in the north, in a vast depression between the Andes ranges. It is called Maracaibo and is connected to the Gulf of Venezuela. The area of this lagoon is 16.3 thousand km2, the length is 220 km. The water in the lagoon is almost fresh, but during high tides, its salinity increases markedly.
The lagoons, which have almost lost contact with the Atlantic Ocean, are located in the southeast of the mainland. The largest of them are Patus and Lagoa Mirin.
A significant part of the continent, especially the Out-Andean East, has large reserves groundwater. In the sandy strata, syneclises are not only in the Amazon, but also in the Guiana lowland, Llanos-Orinoco, Gran Chaco, Pampa, and also in other areas, up to 40-50% of the runoff falls on groundwater.
6. Soils and vegetation.
South America is characterized by a large diversity zonal types of soil and vegetation cover and exceptional richness of flora, including tens of thousands of plant species. This is due to the position of South America between the subequatorial belt of the northern hemisphere and the temperate belt of the southern hemisphere, as well as the peculiarities of the development of the mainland, which first took place in close connection with other continents of the southern hemisphere, and later - in almost complete isolation from large land masses, except for connections with North America through the Isthmus of Panama.
Most of South America, up to 40 ° S, together with Central America and Mexico forms Neotropical floristic kingdom. The southern part of the mainland is within Antarctic realm.
Floristic zoning of South America (according to A.L. Takhtadzhyan)
Within the land that connected the South American platform with the African, obviously, there was a common for both continents flora formation center savannas and tropical forests, which explains the presence in their composition of some common species and genera of plants. However, the separation of Africa and South America at the end of the Mesozoic led to the formation of independent flora on each of these continents and the separation of the Paleotropical and Neotropical kingdoms. The Neotropics are characterized by a great richness and a high degree of endemism of the flora, due to the continuity of its development since the Mesozoic and the presence of several large centers of speciation.
The Neotropics are characterized by endemic families like bromeliads, nasturtiums, cannas, cacti. The oldest center for the formation of the cactus family was apparently located on the Brazilian Highlands, from where they spread throughout the mainland, and after the emergence of the Isthmus of Panama in the Pliocene, they also penetrated to the north, forming a secondary center on the Mexican Highlands.
Flora of the eastern part South America is much older than the flora of the Andes. The formation of the latter occurred gradually, as the mountain system itself arose, partly from elements of the ancient tropical flora of the east, and to a large extent from elements that penetrated from the south, from the Antarctic region, and from the north, from the North American Cordillera. Therefore, there are large species differences between the flora of the Andes and the Extra-Andean East.
Within Antarctic realm south of 40°S there is an endemic, not rich in species, but very peculiar flora. It was formed on the ancient Antarctic continent before the beginning of the continental glaciation of Antarctica. Due to cooling, this flora migrated to the north and has survived to this day in small areas of land within the temperate zone of the southern hemisphere. It reached its greatest development in the southern part of the mainland. The Antarctic flora of South America is characterized by representatives of the bipolar flora found on the arctic and subarctic islands of the northern hemisphere.
The flora of the South American continent has given mankind many valuable plants included in the culture not only in the Western Hemisphere, but also beyond. This is primarily potatoes, the ancient centers of cultivation of which are located in the Peruvian and Bolivian Andes, north of 20 ° S, as well as in Chile, south of 40 ° S, including on the island of Chiloe. Andes - the birthplace of tomatoes, beans, pumpkins. Until now, the exact ancestral home has not been clarified and the wild ancestor of cultivated corn is unknown, but, undoubtedly, it comes from the Neotropical kingdom. South America is also home to the most valuable rubber - hevea, chocolate, cinchona, cassava and many other plants grown in the tropical regions of the Earth. The richest vegetation of South America is an inexhaustible source of enormous natural wealth - food, fodder, industrial, medicinal plants.
The vegetation cover of South America is especially characterized by tropical rainforests, which have no equal on Earth either in the richness of species or in the size of the territory they occupy.
Humid tropical (equatorial) forests of South America on ferrallitic soils, named by A. Humboldt hylaea, and in Brazil called selva, occupy a significant part of the Amazonian lowland, the adjacent areas of the Orinok lowland and the slopes of the Brazilian and Guiana highlands. They are also characteristic of the coastal strip of the Pacific Ocean within Colombia and Ecuador. Thus, tropical rain forests cover areas with an equatorial climate, but, in addition, they grow on the slopes of the Brazilian and Guiana highlands facing the Atlantic Ocean, in higher latitudes, where there are abundant trade winds for most of the year, and in during a short dry period, the lack of rain is compensated by high humidity.
The hylaea of South America is the richest type of vegetation on the Earth in terms of species composition and density of vegetation cover. They are characterized by high height and complexity of the forest canopy. In areas not flooded by rivers in the forest, there are up to five tiers of various plants, of which at least three tiers consist of trees. The height of the highest of them reaches 60-80 m.
Species richness in the hylaea of South America is huge, more than 300000 plant species are endemic. In this respect, they are superior to the tropical rainforests of Africa and even Southeast Asia. The upper tiers of these forests are formed by palm trees, for example, Mauritia aculeata, Mauritia armata, Attalea funifera, as well as various representatives of the legume family. Of the typical American trees, Bertolettia excelsa, which produces nuts with a high fat content, mahogany tree with valuable wood, etc., should be mentioned.
The South American rainforest is characterized by chocolate tree species with caulifloral flowers and fruits sitting right on the trunk.
The fruits of the cultivated chocolate tree (Theobroma cacao), rich in valuable nutritious tonic substances, provide the raw material for making chocolate. These forests are the birthplace of the Hevea rubber plant (Hevea brasiliensis).
Distribution of some plants in South America
Found in the tropical forests of South America symbiosis some trees and ants, such as several species of cecrops (Cecropia peltata, Cecropia adenopus).
The tropical rainforests of South America are particularly rich in creepers and epiphytes, often brightly and beautifully blooming. Among them are representatives of the family of arroinaceae, bromeliads, ferns and orchid flowers, unique in their beauty and brightness. Tropical rainforests rise up the slopes of the mountains up to about 1000-1500 m without undergoing significant changes.
The world's largest array of virgin forests existed in the north of the Amazon basin and on the Guiana Plateau.
However soil under this richest plant community in terms of volume of organic mass, they are thin and poor in nutrients. Decay products, continuously coming to the ground, quickly decompose in a uniformly hot and humid climate and are immediately absorbed by plants without having time to accumulate in the soil. After clearing the forest, the soil cover quickly degrades, and large amounts of fertilizers are required for agricultural use.
As the climate changes, i.e. with the advent of the dry season, tropical rainforests are moving into savannas And tropical woodlands. In the Brazilian Highlands, between the savannahs and the tropical rainforest, there is a strip of almost pure palm forests. Savannahs are common in a large part of the Brazilian Highlands, mainly in its interior regions. In addition, they occupy large areas in the Orinok Lowland and in the central regions of the Guiana Highlands. In Brazil, typical savannahs on red ferralite soils are known as campos. Their herbaceous vegetation consists of high grasses of the genera Paspalum, Andropogon, Aristida, as well as representatives of the legume and Compositae families. Woody forms of vegetation are either completely absent, or are found in the form of individual specimens of mimosa with an umbrella-shaped crown, tree-like cacti, spurges and other xerophytes and succulents.
In the dry northeast of the Brazilian Highlands, a significant area is occupied by the so-called caatinga, which is a sparse forest of drought-resistant trees and shrubs on red-brown soils. Many of them lose their leaves during the dry period of the year, others have a swollen trunk in which moisture accumulates, for example, the cottonwort (Cavanillesia platanifolia). The trunks and branches of Caatinga trees are often covered with creepers and epiphytic plants. There are also several types of palm trees. The most remarkable caatinga tree is the carnauba wax palm (Copernicia prunifera), which produces vegetable wax, which is scraped or boiled from its large (up to 2 m long) leaves. Wax is used for making candles, rubbing floors and other purposes. Sago and palm flour are obtained from the upper part of the carnauba trunk, the leaves are used to cover roofs and weave various products, the roots are used in medicine, and the local population uses the fruits in raw and boiled form. No wonder the people of Brazil call carnauba the tree of life.
On the Gran Chaco plain, in especially arid regions, on brown-red soils, thickets of thorny bushes And sparse forests. In their composition, two species belong to different families, they are known under the common name "quebracho" ("break the ax"). These trees contain a large amount of tannins: red quebracho (Schinopsis Lorentzii) - up to 25%, white quebracho (Aspidosperma quebracho blanco) - somewhat less. Their wood is heavy, dense, does not rot and sinks in water. Quebracho is heavily cut down. At special factories, tanning extract is obtained from it, sleepers, piles and other items are made from wood, designed for a long stay in water. Algarrobo (Prosopis juliflora) is also found in the forests - a tree from the mimosa family with a twisted trunk and a strongly branching spreading crown. The fine, delicate foliage of the algarrobo leaves no shade. The low tiers of the forest are often represented by thorny shrubs that form impenetrable thickets.
The savannahs of the northern hemisphere differ from the southern savannahs in appearance and species composition of the flora. To the south of the equator, among the thickets of cereals and dicotyledons, palm trees rise: copernicia (Copernicia spp.) - in drier places, winding mauritia (Mauritia flexuosa) - in swampy or flooded areas. The wood of these palms is used as a building material, the leaves are used for weaving various products, the fruits and core of the Mauritia trunk are edible. Acacias and tall tree cacti are also numerous.
Red and red-brown soil savannahs and tropical woodlands are characterized by a higher humus content and greater fertility than the soils of moist forests. Therefore, in the areas of their distribution are the main areas of plowed land with plantations of coffee trees, cotton, bananas and other cultivated plants exported from Africa.
pacific coast between 5 and 27° S and the Atacama Basin, with their constant lack of rain, have the most typical desert soils and vegetation in South America. Plots of almost barren stony soils alternate with massifs of free-flowing sands and vast surfaces occupied by saltpeter solonchaks. Extremely sparse vegetation is represented by sparsely standing cacti, thorny cushion-like shrubs and ephemera of bulbous and tuberous plants.
subtropical vegetation occupies relatively small areas in South America.
The extreme southeast of the Brazilian Highlands, which receives abundant rainfall throughout the year, is covered subtropical forests from araucaria with an undergrowth of various shrubs, including Paraguayan tea (Ilex paraguaiensis). Paraguayan tea leaves are used by the local population to make a widespread hot drink that replaces tea. According to the name of the round vessel in which this drink is made, it is called mate or yerba mate.
The second type of subtropical vegetation of South America is subtropical steppe, or pampas, characteristic of the eastern, most humid parts of the La Plata lowland south of 30 ° S, is a herbaceous cereal vegetation on fertile reddish-black soils formed on volcanic rocks. It consists of South American species of those genera of cereals that are widespread in Europe in the steppes of the temperate zone (feather grass, bearded vulture, fescue). The pampa is connected with the forests of the Brazilian Highlands by a transitional type of vegetation, close to the forest-steppe, where grasses are combined with thickets of evergreen shrubs. The vegetation of the pampas has been the most severely destroyed and is now almost completely replaced by crops of wheat and other cultivated plants. To the west and south, as precipitation decreases, vegetation of dry subtropical steppes and semi-deserts appears on gray-brown soils and gray soils with spots of salt marshes in place of dried lakes.
The subtropical vegetation and soils of the Pacific coast are similar in appearance to the vegetation and soils of the European mediterranean. Thickets of evergreen shrubs on brown soils predominate.
The extreme southeast (Patagonia) is characterized by vegetation dry steppes and semi-deserts of the temperate zone. Gray-brown soils predominate, salinization is widespread. The vegetation cover is dominated by tall grasses (Roa flabellata, etc.) and various xerophytic shrubs, often pillow-shaped, undersized cacti.
In the extreme southwest of the mainland, with its oceanic climate, insignificant annual temperature differences and an abundance of precipitation, moisture-loving evergreen subantarctic forests, multi-tiered and very diverse in composition. They are close to tropical forests in the richness and diversity of plant life forms and the complexity of the forest canopy structure. They abound with vines, mosses, lichens. Along with various tall coniferous trees of the genera Fitzroya, Araucaria and others, evergreen deciduous species are common, for example, southern beeches (Nothofagus spp.), Magnolia, etc. There are many ferns and bamboos in the undergrowth. These moisture-soaked forests are difficult to clear and uproot. They are still one of the most important natural resources Chile, though heavily affected by logging and fires. Almost without changing their composition, the forests rise along the slopes of the mountains to a height of 2000 m. Forest burozems develop under these forests. To the south, as it gets colder, the forests become depleted, creepers, tree ferns and bamboo disappear. Conifers (Podocarpus andinus, Austrocedrus chilensis) predominate, but evergreen beeches and magnolias remain. Beneath these depleted subantarctic forests, podzolic soils form.
Influenced economic activity human vegetation has undergone significant changes. In just 15 years, from 1980 to 1995, the area of forests in South America decreased by 124 million hectares. In Bolivia, Venezuela, Paraguay and Ecuador, the rate of deforestation over this period exceeded 1% per year. For example, in 1945, in the eastern regions of Paraguay, forests occupied 8.8 million hectares (or 55% of the total area), and in 1991 their area was only 2.9 million hectares (18%). In Brazil, about 15 million hectares of forests were destroyed between 1988 and 1997. It should be noted that after 1995 there has been a marked decrease in the rate of deforestation.
main reason deforestation in the Brazilian Amazon, there remains an expansion of agricultural land, mostly permanent pasture. The destruction of forests leads to the destruction of the upper soil horizon, the development of accelerated erosion and other processes of soil degradation. Due to deforestation and pasture overload, soil degradation processes have affected almost 250 million hectares of land.
7. Animal world.
No less rich than the vegetation cover, the fauna of South America is also characterized. The modern fauna, like the flora of the mainland, was formed starting from the end of the Cretaceous period. in isolation and little climate change. The antiquity of the fauna and the presence in its composition of a large number of endemic forms are associated with this. In addition, there are some common features of the fauna of South America and other continents of the southern hemisphere, which indicates a long-standing relationship between them. An example is marsupials, preserved only in South America and Australia.
All the monkeys of South America belong to the broad-nosed group, which is absent from the fauna of the Old World.
A feature of the fauna of South America is also the presence in its composition of three endemic families of edentulous, united in one order. A large number of endemic species, genera and even families are found among predators, herbivores and rodents.
The very rich and peculiar fauna of South America (together with Central America) belongs neotropical region and is included within its two subregions - Brazilian and Chile-Patagonian.
Tropical rainforests
The greatest originality and wealth are characterized by tropical rainforests, animals there hide in dense thickets or spend most of their time on tall trees. Adaptation to an arboreal way of life is one of the features of animals in the Amazonian forests, as well as animals in the forests of the Congo Basin in Africa or the Malay Archipelago in Asia.
American (broad-nosed) monkeys live in the tropical forests of South America, divided into two families - marmosets and cebids. Marmoset monkeys are small. The smallest of them reach a length of no more than 15-16 cm, limbs equipped with claws help them to stay on tree trunks. Many cebids are characterized by a strong tail, with which they cling to tree branches, it acts as a fifth limb. Among them, a genus of howler monkeys stands out, which received its name for the ability to make far-audible cries. Spider monkeys with long flexible limbs are widespread.
Of the representatives of the order of edentulous in tropical forests live sloths(Bradypodidae). They are sedentary and spend most of their time hanging in trees, feeding on leaves and shoots. Sloths climb trees confidently and rarely fall to the ground.
Distribution of some animals in South America
Some are also adapted to life on trees. anteaters. For example, it freely climbs tamandua trees; the small anteater, which has a tenacious tail, also spends most of its time in trees. The large anteater is common in forests and savannahs, leads a terrestrial lifestyle.
In tropical forests there are predators from the family feline: ocelots, small jaguarundis, as well as large and strong jaguars. Of the predators belonging to the family canine, an interesting little-studied forest, or bush, dog living in the rainforests of Brazil, Suriname and Guyana. Tree-hunting forest animals include the nasua (Nasua) and the kinkajou (Potos flavus).
Ungulates, few in South America, are represented in the forests by only a few genera. Among them are the tapir (Tapirus terrestris), the small black peccary pig, and the small South American pointed deer.
Characteristic representatives rodents in the forests of the Amazonian lowland and other regions of South America - arboreal chain-tailed porcupines coendu (genus Coendou). Agoutis (Dasyprocta agouti), which are found in the forests of Brazil, cause great damage to plantations of tropical crops. Almost throughout the mainland, especially in the Amazonian forests, the capybara capybara (Hydrochoerus hydrochaeris) is common - the largest representative of rodents, whose body length reaches 120 cm.
Several species live in the forests of South and Central America. marsupial rats, or opossums. Some of them are equipped with a tenacious tail and climb trees well. The Amazon forests are teeming with bats, among which there are species that feed on the blood of warm-blooded animals.
Reptiles and amphibians are very richly represented in the forests. From reptiles the anaconda water boa (Eunectes murinus) and the terrestrial arboreal dog-headed boa (Corallus caninus) stand out. Many poisonous snakes, lizards. There are crocodiles in the rivers. From amphibians many frogs, some of them lead an arboreal lifestyle.
There are many different types of forests birds, especially brightly colored parrots. The largest of the parrots, the macaw, is the most typical. In addition, small parakeets and beautiful, brightly feathered green parrots are widespread. The most characteristic representatives of the avifauna of South America, in particular tropical forests, are hummingbirds. These small colorful birds that feed on the nectar of flowers are called insect birds.
Also found in the forests hoatzins(Opisthocomus hoatzin), whose chicks have claws on their wings to help them climb trees, sun herons and shuttle-billed herons, harpies are huge birds of prey that prey on young deer, monkeys and sloths.
One of the features of the tropical forests of the mainland is a large number insects, many of which are endemic. Diurnal and nocturnal butterflies, various beetles, ants abound. Many butterflies and beetles are beautifully colored. Some beetles glow so brightly at night that you can read near them. Butterflies are huge; the largest of them is agrippa, its wingspan reaches almost 30 cm.
Savannas, woodlands and steppes
Fauna more dry and open spaces South America - savannas, tropical woodlands, subtropical steppes - different than in dense forests. Of the predators, in addition to the jaguar, the cougar (found almost throughout South America and entering North America), the ocelot, and the pampa cat are common. The southern part of the mainland is characterized by a maned wolf from the canine family. On the plains and in mountainous regions, the pampa fox is found almost throughout the mainland, in the extreme south - the Magellanic fox. Of the ungulates, a small pampas deer is common.
Representatives of the third American family of edentulous are found in savannahs, forests and arable land - armadillos(Dasypodidae) - animals equipped with a strong bone shell. When danger approaches, they burrow into the ground.
From rodents in the savannahs and steppes there are viscacha and tuko-tuko living in the land. The swamp beaver, or nutria, is widespread along the banks of reservoirs, the fur of which is highly valued on the world market.
From birds in addition to numerous parrots and hummingbirds, there are also rhea (genus Rhea) - South American representatives of the ostrich-like order, some large birds of prey.
In the savannahs and steppes there are many snake And lizards. A characteristic feature of the landscapes of South America is a large number termite mounds. Some areas of South America periodically suffer from locust invasions.
Andes
The mountain fauna of the Andes is distinguished by peculiar features. It includes many endemic animals not found in the eastern part of the mainland.
South American representatives of the camelid family - llamas - are common throughout the mountainous region. There are two types of wild llamas - vigogne And guanaco. In the past, the Indians hunted them for their meat and wool. Guanaco was found not only in the mountains, but also on the Patagonian plateau and in the Pampas. Now wild llamas are rare. The Indians in the Andes breed two domestic species of llamas - the llama itself and the alpaca. Llamas are large and strong animals, used as pack animals on difficult mountain roads, their milk and meat are eaten, and coarse fabrics are made from wool. Alpaca (Lama pacos) is bred only for its soft fur.
Also found in the Andes spectacled bear, some marsupials. Small endemic rodents used to be widespread chinchillas(Chinchilla). Their soft, silky gray fur was considered one of the finest and most expensive furs. Therefore, at present, the number of chinchillas has decreased to a large extent.
Birds are represented in the Andes by endemic mountain species of the same genera and families that are common in the east of the mainland. Of the carnivores, the condor (Vul griphus) is interesting - the largest representative of this order.
The fauna is unique volcanic Galapagos Islands, in its composition the main place belongs to large reptiles- gigantic land turtles and sea lizards (iguanas). There are also many different birds, among which there are representatives of both tropical and Antarctic avifauna (parrots and penguins brought by the cold current, cormorants, etc.). Among the few mammals are eared seals, some rodents and bats. Domestic animals (goats, dogs, pigs) were brought to the islands and ran wild.
As a result of habitat destruction, the number of many species of animals decreased. Currently in South America Endangered there are 161 species of mammals, 269 species of birds, 32 species of reptiles, 14 species of amphibians and 17 species of fish.
For the protection of animals, plants and ecosystems in general, reserves and protected areas other categories. In 2002, there were 706 protected areas in the five IUCN categories in South America, covering an area of almost OUT of million hectares. Among the most famous national parks are Los Glaciares in Argentina, Iguazu in Brazil and Argentina, Itatia in Brazil, Vicente Perez Rosales in Chile, and others. A biosphere reserve was also created on the Galapagos Islands.
Similar information.
Savannahs and light forests are typical of the subequatorial climate with a sharp division of the year into dry and rainy seasons. Savannahs are climatic regions characteristic of more elevated tropical countries with a dry continental climate. In Asia, the largest areas of the savannah and light forest zone are confined to the Deccan Plateau and the inner parts of the Indochina Peninsula.
A distinctive feature of the climate of the savannas is the alternation of dry and wet seasons, which take about half a year, replacing each other. The change of two different air masses is characteristic - humid equatorial and dry tropical. Monsoon winds, bringing seasonal rains, significantly affect the climate of the savannahs. Since these landscapes are located between the very humid natural zones of the equatorial forests and the very dry zones of the deserts, they are constantly influenced by both. But moisture is not present in the savannas long enough for multi-tiered forests to grow there, and dry "winter periods" of 2-3 months do not allow the savannah to turn into a harsh desert. "Winter" in the savannah is a dry and relatively cold period lasting two to three months. During this time, the trees shed their leaves, the grasses wither and dry up, and sometimes burn out. The contrast of day and night temperatures reaches 15-18 degrees Celsius. During this period, many rivers dry up, become shallow, and the groundwater level drops. "Winter" is replaced by "spring", when the flowering of still leafless trees and shrubs begins. The "summer" period - the most humid and rainy - lasts, as a rule, four to five months. The temperature drops, and the humidity increases, amounting to almost 90%. At this time, the trees open their leaves, grasses grow wildly, and the soil is filled with water. The rivers become full. Before the next "winter" comes a short "autumn", when cereals and trees bear fruit, evaporation decreases. Nature is preparing for a new dry period.
The savannas are characterized by the dominance of red-brown and black merged soils. These soils are characterized by low humus content (1.5-3%). Soil reaction is close to neutral, they are saturated with bases. In some profiles, in the lower part, there are ferruginous concretions. The total thickness of the profile on leveled surfaces is 1.5-2 meters. Dark-colored (black) coalesced montmorillonite soils appear in relief depressions, in the area of distribution of red-brown soils. Such combinations are especially widespread in the southern part of the Deccan Plateau.
Vegetable world
In the savannahs of Asia, there are trees and shrubs from legumes, myrtle, dipterocarp (Figure 4). Tree-shrub forms of savannahs are characterized by a powerful root system that penetrates to a considerable depth even with a relatively small size of the aerial part, the presence of a thick crust on the trunks. The trees are often stunted, with winding, sometimes straight or curved trunks, with spreading crowns. The umbrella-shaped form of the crown is widespread. On the whole, savannah communities are comparatively poor in floristics and have little diversity in structure. Depending on the moisture conditions, the height of the herbage, the degree of its density, and the species composition of trees and shrubs vary. Grasses that form the basis of savannah communities are characterized by more or less pronounced xeromorphism, their vegetative parts are represented by dense tufts, and long rhizomes are developed. The size of plants, depending on moisture and soil conditions, varies quite significantly. Generative shoots of cereals that produce a large number of seeds reach especially high heights. Woody vegetation gives way to formations of tall grasses: bearded man, alang-alang, wild sugarcane. In the summer the savannah turns green, in the winter it turns yellow. Solitary palms, banyans and acacias.
47 Savannah and woodland zone
1.Location:
The zone of savannas and light forests is developed in Africa, South America, Asia (Hindostan) and in the north-west of Australia. In Africa, it covers Sudan, East Africa, the watershed plateaus of the Congo - Zambezi and Zambezi - Limpopo, part of the Kalahari Basin; in South America - the Orinoco basin and part of the Guiana massif, as well as the vast territory of the Brazilian massif and the Gran Chaco; in Australia - the northern quarter of the mainland; In Asia - Hindustan south of 220 N.S.
2.Characteristics of temperature regime, precipitation:
The temperature of the coldest month within the zone is from 12 to 200, the warmest is 20-350. atmospheric precipitation per year in different areas from 100 to 500 mm (in some places up to 1000 mm). The change of dry and wet seasons is very distinct. The river network is sparse: during the rainy period - violent short floods, during the drought - long shallow water, small watercourses dry up.
The soils are black, red-brown, brown, gray-brown; in India, in red-brown soils, a compacted horizon of carbonate nodules (kankara) is formed at shallow depths.
4.Vegetation:
Basically, the savannah is a tropical type of herbaceous vegetation, which differs from the steppe one in the presence of xerophilic low-growing sparsely standing trees, many of which have an umbrella crown. The main background of the savanna is created by hard-leaved cereals. Trees growing in the savannah have a long root system, reaching 50-60 m, many trees acquire an umbrella-shaped crown (acacia) to reduce evaporation. In West Africa, large areas are occupied by wet savannas, in which the height of cereals can reach 5 m. In dry savannas, the height of cereals is much lower, powerful deciduous trees - baobabs are often found (height up to 25 m, trunk diameter - 10 m or more, the age of the trees can reach 1000 years). In the savannas of Australia, eucalyptus trees grow with an admixture of acacias, large spaces are occupied by dense thickets of xerophytic shrubs - scrub.
5.Animal world:
The fauna of the savannah is exceptionally rich. The abundance of herbs also attracts an abundance of ungulates, many rodents, large and small predators, and reptiles. In the savannas of Africa, ungulates are common, most of them are antelopes. There are rhinos, giraffes, elephants, lions, jackals, hyenas. Various types of kangaroos live in the savannahs of Australia, there are a lot of rodents and insects.
48 Deserts of the globe.
Deserts are common in the temperate zone northern hemisphere, subtropical And tropical belts of the Northern and Southern hemispheres. They are characterized by moistening conditions (the annual amount of precipitation is less than 200 mm, and in extra-arid regions - less than 50 mm; the moisture coefficient, which reflects the ratio of precipitation and evaporation, is 0-0.15). In the relief - a complex combination of uplands, hillocks and island mountains with structural layered plains, ancient river valleys and closed lake depressions. erosional the type of relief formation is strongly weakened, eolian relief forms are widespread. For the most part, the territory of the deserts is drainless, sometimes they are crossed by transit rivers ( Syrdarya, Amu Darya, Nile, Huanghe and others); many drying lakes and rivers, often changing their shape and size ( Lopnor, Chad, Air), characterized by periodically drying watercourses. Groundwater is often mineralized. Soils are poorly developed, characterized by the predominance of water-soluble salts in the soil solution over organic matter, salt crusts are common. The vegetation cover is sparse (the distance between neighboring plants is from several tens of cm to several meters or more) and usually covers less than 50% of the soil surface; practically absent under extraarid conditions.
Sandy deserts are inhabited from plants mainly by thorny bushes, from animals - reptiles and small steppe animals. In sandy deserts above the places where groundwater occurs, oases- "Islands" with dense vegetation and reservoirs. The snowy deserts are mostly found above the Arctic Circles and are inhabited by cold-hardy animals.
By the nature of soils and soils:
sandy - on loose deposits of ancient alluvial plains;
loess - on loess deposits of piedmont plains;
loamy - on slightly carbonate cover loams of the plains;
clay takyr - on the piedmont plains and in ancient river deltas;
clayey - in the lowlands, composed of salt-bearing marls and clays,
pebble and sand-pebble - on gypsum plateaus and piedmont plains;
gravelly gypsum - on boards and young piedmont plains;
stony - in low mountains and small hills;
solonchak - in saline depressions of the relief and along the sea coasts.
Knowing the elementary basics from geography lessons, most students will unanimously say that the savannah and light forests are the same natural zone as the taiga, steppe, tundra, desert, etc. This article is intended to give a more definite and clear concept of the savannah and woodlands.
Geographical position
So, savannah and light forests are a natural zone that can only be found in certain areas. They are widespread in both hemispheres, and small areas are also located in the subtropics and tropics. More precisely, they are territorially located on almost half of the African continent (about 40% of the total area). The savanna and woodlands are also very common in South America, in the northern and eastern parts of Asia (for example, in Indochina), and also in Australia.
Most often, these are places with insufficient moisture for the normal growth of moist forests. Usually they begin their "development" in the depths of the mainland.
Zone Climate features
For most natural areas, the main reason for the characteristics of the animal and plant world, as well as the state of the soil, is, first of all, the climate, and directly the temperature regime and temperature changes (both daily and seasonal).
Based on the above-described features of the geographical position of the savannahs, it is reasonable to conclude that hot weather is typical for all seasons of the year, and dry tropical air is noted in winter, while in summer, on the contrary, humid equatorial air prevails. The removal of these territories from, respectively, affects the reduction of the rainy season to a minimum of 2-3 months from its characteristic 8-9. Seasonal temperature differences are relatively stable - the maximum difference is 20 degrees. However, the daily difference is very large - it can reach a difference of as much as 25 degrees.
Soils
The condition of the soil, its fertility directly depend on the duration of the rainy period and is characterized by increased leaching. Thus, closer to the equator, the natural zone of savannahs and light forests, namely their soil, is characterized by a huge content of red soils. In areas where the rainy season lasts for 7-9 months, most soils are ferralitic. Places with rainy seasons of 6 months or less are "rich" in red-brown savannah soils. In poorly irrigated areas with rains falling in just two to three months, unsuitable soils are formed with a very thin layer of humus (humus) - up to 3-5% maximum.
Even soils such as savannahs have found their way into human activities - the most suitable of them are used for grazing livestock, as well as for growing various crops, but due to their misuse, already impoverished areas turn into depleted and deserted areas, unable to in the future, at least somehow feed both people and animals.
Flora and fauna
To survive in such changeable conditions, animals need to adapt to the zone, as, in fact, in all other regions. Savannah and light forests surprise with the richest fauna. So, in Africa, on the territories of the savannas, mainly mammals live: giraffes, rhinos, elephants, wildebeest, hyenas, cheetahs, lions, zebras, etc. In South America, anteaters, armadillos, rhea ostriches, etc. are found. and the number of birds - this is the notorious secretary bird, African ostriches, sunbird, marabou, etc. In Australia, the "inhabitants" of the savannas and woodlands are kangaroos, their fellow marsupials, wild dingo dogs. During the drought, herbivores migrate to areas better supplied with water and food, on the way to which they themselves sometimes become the objects of hunting for most predators (and humans too). Termites are common in savannahs.
Describing flora such as savannah and woodlands, it is impossible not to mention baobabs - amazing trees, like camels, accumulating water reserves in their trunk. Acacias, epiphytes, palm trees, quebrachos, tree-like cacti, etc. are also often found. During the period of drought, many of them turn yellow, wither, but with the advent of rains, the whole environment seems to be reborn and once again gives the arrived animals the opportunity to gain strength and prepare for the next drought .
Natural zone of savannah and woodlands
slide 2
Savannahs and woodlands
Savannahs and light forests are located on all continents except Antarctica.
Savannas and woodlands are located in the equatorial, subequatorial, subtropical and tropical climatic zones.
slide 3
Definition of a natural area
A natural zone is a large natural complex with a common temperature and moisture conditions, soils, vegetation and wildlife.
Savannahs and light forests are open spaces dominated by herbaceous cover with individual trees or groups of trees and bushes of the hot zone.
slide 4
Climatic features
In savannahs and light forests, two seasons of the year are pronounced:
- dry
- wet
In the dry winter period, the grasses burn out, the trees shed their leaves, life stops, the savanna becomes yellow.
In the rainy season, nature comes to life, lush grasses grow, the savannah is filled with life.
slide 5
Soils
In savannahs and light forests, the soils are red-brown.
Formed during the rainy season: the soil is washed out.
In the dry period, the plant litter of the herbaceous cover does not decompose completely, because. slow down the activity of microorganisms.
Humus accumulates in the soil.
slide 6
Vegetable world
Each continent has its own unique flora of savannahs and light forests.
- Africa
- Australia
Slide 7
- America
- Eurasia
