INTRODUCTION

South America is a continent crossed by the equator, most of which is located in Southern hemisphere... South America is located between The Pacific Ocean and Atlantic Ocean... It was connected to North America more recently with the formation of the Isthmus of Panama. The Andes, a relatively young and seismically unstable chain of mountains, stretches along western border continent; the land to the east of the Andes is occupied mainly by tropical forests, the vast basin of the Amazon River. The largest country in South America by area and population - Brazil. Regions of South America include the Andean states, the Guyana Highlands, the Southern Cone, and Eastern South America. South America also includes various islands, most of which belong to the countries of the continent. The Caribbean territories belong to North America. Countries in South America that border Caribbean- including Colombia, Venezuela, Guyana, Suriname and French Guiana - known as Caribbean South America. In this course work we will consider the natural zones and geographic zones of South America, as well as human settlement and its impact on the nature of South America.

> NATURAL ZONES OF THE EQUATORIAL AND SUB-EQUATORIAL BELT

> Zone of humid equatorial forests

Wet equatorial forests - evergreen forests, mainly in the equatorial, less often in the subequatorial belts in the north of South America, in Central America, in Western Equatorial Africa, in the Indo-Malay region. In the Amazon basin, they are called helium, selva. Distributed in areas with annual precipitation of more than 1500 mm, relatively evenly distributed over the seasons. Characteristically big variety species of trees: from 40 to 170 species are found per hectare. Most trees have straight, columnar trunks, branching only in the upper part. The tallest trees reach heights. 50-60 m, trees avg. tier - 20-30 m, lower - approx. 10 m. Many trees have board-like roots, sometimes rising to a height. 8 m. In swampy forests, trees have stilted roots. Change of foliage different types trees happen in different ways: some shed their leaves gradually throughout the year, others only at certain periods. Opening young leaves initially hang, as if withered, sharply differing in color, which is characterized by a wide range of colors - from white and pale green to crimson and burgundy. Flowering and fruiting also occur unequally: continuously throughout the year or periodically - once or several times a year. Often, branches with fruits, flowers and young leaves can be seen on the same tree. Many trees are characterized by caulifloria - the formation of flowers and inflorescences on the trunks and leafless areas of the branches. The dense crowns of trees almost do not allow sunlight to pass through, so there are very few grasses and shrubs under their canopy. In the equatorial forests there are many lianas, mainly with woody stems, less often grassy ones. Their trunks reach a diameter of 20 cm, and the leaves are raised to the height of tree crowns. Some lianas, for example, rattan palms, rest on tree trunks with short shoots or special outgrowths; others, such as vanilla, are fixed with adventitious roots; however, most tropical vines are curly. There are often cases when the trunk of a vine is so strong, and the crown is so closely intertwined with several trees that the tree braided by it does not fall after death. Epiphytes are very diverse and numerous - plants growing on trunks, branches, and epiphylls - on tree leaves. They do not suck out nutritious juices from the host plant, but use it only as a support for growth. Epiphytes from the bromeliad family accumulate water in the rosettes of leaves. Orchids store nutrients in the thickened areas of the shoots, roots or leaves. Breeding epiphytes, for example. ferns "bird's nest" and "antlers" accumulate soil between roots, epiphytes-sconces - under the leaves adjacent to tree trunks. In America, even some types of cacti are epiphytes. The humid equatorial forests were being exterminated by predators and continue to be exterminated. By now, their area has already halved and continues to decrease at a rate of 1.25% per year. They are inhabited by St. 2/3 of all species of plants and animals on Earth, many of which die, even without being discovered and explored by man. In place of the destroyed primeval forest, low-growing and very species-poor forests of fast-growing trees begin to grow. With regular fires and clearings, secondary forests are replaced by savannas or pure thickets of cereals.

> Subequatorial forest zone

Sub zone equatorial forests located on the outskirts equatorial belt... Subequatorial forests in the hinterland subequatorial belt, in the outer - savannas. Subequatorial forests are divided into 2 pozdons: 1. Seasonal moist forests... Dry season 3.5-4 months, ferralite soils. The main background of forests in the north of the Guiana Highlands. 2. Subzone of permanently humid subequatorial forests. Occupies only the North-East of the Guiana Plateau. Dry season less than two months. The soils are ferralite and red-yellow.

> Zone of savannas, woodlands and shrubs

Zones of savannas, woodlands and shrubs are located mainly in the subequatorial and partly in the tropical climatic zones. The savannahs occupy the Orinoco Plain, where they are called llanos, as well as the interior of the Guiana and Brazilian Highlands (campos).

Savannah soils are red ferralite and red-brown. In the savannahs of the northern hemisphere, sparsely standing palms and acacias grow among tall grasses. Gallery forests are characteristic along the river banks. In the savannas of the Brazilian Highlands, the grass cover, as in the llanos, consists of tall grasses and legumes. But woody vegetation is much poorer, mimosas, tree-like cacti, and milkweed predominate. In the northeast of the Brazilian Highlands and the Inner Tropical Plains, in a drier climate (up to 400 mm of precipitation per year), tough grasses, thorny shrubs, bottle trees, low-growing open forests of kebracho - a tree with very hard wood (“kebracho” in translated means "break the ax"). In the fauna of the savannahs of South America, there are few ungulates (small deer); there are baker-pigs, armadillos, anteaters, and of the predators - the cougar. Subzones: 1. Wet savannahs. Orinok lowland (llanos). A clear division into a dry period, 3.5-4 months. The soils are red, there are areas of yellow and red-yellow. Palm vegetation and herbs. 2. Dry shrub savannas and woodlands. central part Brazilian Highlands, North-East of the Orinoco Plain. The amount of precipitation is not more than 700 mm, the soils are brown-red. The grass cover is sparse, represented mainly by grasses, shrubs are characteristic. This type of savanna is called campos. Dry period about 5 months. 3. Kaatina (subzone of deserted woodland). North-East of the Brazilian Highlands. Almost complete absence of grass cover, only shrubs and wax palm grow. The soils are red-brown.

"Climatic zones of Africa" ​​- a climate-forming factor. My dream. Climate of Africa. Winds in summer. River basin. The main climatic zones. Africa. Air mass. Climatic zone... The hottest continent.

"Savannahs of Africa" ​​- Umbrella acacia - an inhabitant of the African savannah. Africa is the second largest continent the globe... A lion eats over 10 kg of meat at a time. Some plants are capable of storing moisture in their trunks (baobabs, bottle trees). Surprisingly, it is not lions who hunt, but lionesses. From woody vegetation, there are palms, various acacias, tree-like cacti. The baobab is one of the most honored veterans of the plant kingdom.

"Forests of Africa" ​​- Fagara. Fly Tsetse. Characteristics of the natural zones of Africa. Snail Achatina. Young shoots of branches. Dusk and dampness. Organic world giley. Many vines. Atlas. Gilea. Goliath. Climate. Natural areas africa. The relationship of natural components. What is called a "natural area". Geographical position... Middle and lower tier. Animal world... Trees. Equatorial forests. Upper tier. Okapi. Pygmy hippopotamus.

"Climate and Natural Zones of Africa" ​​- Geographic Zoning. Various antelopes. Date palm. Animals. Savannah. Animal world. Tropical deserts. Africa. Mediterranean natural area. Wet equatorial forest. Natural areas of Africa.

African Deserts - Choose the correct statement. Plants in deserts survive on very long roots. Fenneck, or desert fox. Cairo. Soils in the desert. Plants in the desert. Choose only desert animals. Sahara Desert Zone. In the African desert. Desert. Oases. Climate. Desert fauna. Jerboa.

"Map of natural areas of Africa" ​​- Ostrich. Climate. The organic world of the savannahs. Notes of an unlucky tourist. Changing the nature of Africa by man. Leopard. Savannah zone. Natural areas of africa. Gorilla. Animal world. Elephant. The organic world of Gilea. Rich vegetation. Wet equatorial forests. Zebra. Cereals.

The natural zones of the Earth are most clearly distinguished by their vegetation cover, therefore, the names of natural zones are given according to the main distinguishing feature - vegetation.

Natural zones of the equatorial and subequatorial geographic zones

The largest areas are in Africa, South America, South East Asia and Oceania. Wet equatorial forests (gileae) are formed under conditions of constantly high temperatures and high rainfall throughout the year. These are the richest forests on the planet in terms of species composition. They are characterized by density, multi-tiered, abundant lianas and epiphytes (plants growing on other plants - mosses, orchids, ferns).

In South America, trees with valuable wood - rosewood and pau brazil, as well as ficuses, hevea - grow under the giant trees of seiba and bertolecia; in the lower tiers - palms and a chocolate tree. In Africa, grow oil and wine palms, cola, breadfruit, in the lower tiers - bananas and coffee trees. Valuable wood is possessed by mahogany, iron, ebony, sandalwood. Equatorial forests South-East Asia and about. New Guinea is poorer in species composition: palm trees, ficuses, tree ferns. Gileas form on poor, red-yellow ferralite soils.

Gilea animals are adapted to life in trees. Many have a prehensile tail, like a sloth, a possum, a prehensile porcupine. Only in the gileys of the Old World were the great apes preserved - gorillas, orangutans, chimpanzees. From land animals - forest antelopes, tapirs. There are predators: jaguar, leopard. There are many birds: parrots, guinea fowls, peacocks, toucans, hummingbirds. The transition zone between equatorial forests and savannas are subequatorial variable humid forests. The presence of a dry period causes the appearance of deciduous trees. Ficuses and palms prevail among evergreen trees.

Savannahs and woodlands are located mainly in subequatorial geographic zones, largest areas concentrated in Africa, South America, Australia and South Asia. Savannahs are predominantly open grass plains with freestanding trees and groves. They are characterized by an alternation of dry winter and wet summer seasons... Depending on the moisture content, wet, typical and deserted savannas are distinguished, under which red, brown-red and red-brown soils develop, respectively. The herbaceous cover is formed by bearded and feather grass. Of the trees for the savannahs of South America, palm trees (Mauritius, wine, wax) are characteristic. In the African savannas, in addition to palm trees (olive, dum), baobabs are often found. Casuarins are typical for Australia. Acacias are ubiquitous.

The African savannah is characterized by an abundance of ungulates (antelope, giraffe, elephant, zebra, buffalo, rhinos, hippos) and predators (lion, leopard, cheetah). For the South American savannas, animals with a protective brown coloration (spoke-horned deer, maned wolf), rodents (capybara) and edentulous ones (armadillo, anteater) are typical. An integral part of the Australian savannah are marsupials (kangaroos, wombats) and large flightless birds (emu, cassowary).

Natural zones of tropical and subtropical geographical zones

Forests form in the eastern oceanic areas of the tropics, and deserts and semi-deserts in the central continental and western oceanic areas washed by cold currents.

Tropical deserts and semi-deserts are the most extensive natural zone of the tropical zones. The largest desert areas are concentrated in tropical latitudes ah Africa, the Arabian Peninsula and central Australia. (Determine from the atlas map which deserts are located inside the mainland, and which ones are on west coasts.) These are very hot and dry areas with poor vegetation and wildlife. By vegetation, deserts are distinguished: gramineous-dwarf shrubs, dwarf shrubs and succulent deserts. Tropical semi-deserts and deserts North Africa- cereal-dwarf shrubs (acacia, tamarisk, wild millet, dwarf saxaul, camel thorn). In the oases, the main cultivated crop is the date palm. For deserts South Africa characteristic succulents storing moisture (aloe, milkweed, wild watermelons), as well as irises and lilies blooming during short rains. The soils of semi-deserts are sierozem, deserts are stony or sandy.

For the deserts of Australia, the bushy grass spinifex is characteristic, for the semi-deserts - thickets of swans, salt-tolerant species of acacias. On the gray soils of the coastal deserts of South America, dry grasses and cacti grow, on the gravelly soils of high-mountain deserts - creeping and pillow-like grasses, thorny shrubs.

In the well-hydrated east tropical belt moist and variable wet rainforests on red soils. In South America, palm trees, ficuses, mahogany, ceiba grow in them.

In the humid tropics of Madagascar, the "tree of travelers", iron, ebony, and rubber plants grow. Lemurs have survived on the island. For rainforest Australia is characterized by eucalyptus, evergreen beeches, araucaria. Marsupials (tree kangaroo, koala) and "living fossils" - the platypus and the echidna live.

Hard-leaved evergreen forests and shrubs are widespread on the western outskirts of the subtropical geographic zone in a Mediterranean climate. Classically hard-leaved evergreen forests are represented in the Mediterranean: cork and stone oak, alepine pine, pine, Atlas and Lebanese cedars, cypress with a rich undergrowth of wild olive, laurel, pistachio, myrtle, strawberry tree.

The species composition of the vegetation of this natural zone differs on different continents. Fir, cedar, thuja, pine and ancient sequoias grow in North America. In South America - evergreen beeches, teak, perseus. The forests of South Africa are composed of silver wood, Cape olive, African walnut; Australia - from eucalyptus and "herbaceous tree". The natural vegetation of the natural zone has been largely reduced; it was replaced by impoverished thickets of shrubs on gray-brown soils. The brown soils of the forests are highly fertile, therefore they are plowed up for the cultivation of subtropical crops (olive, citrus, vines, etc.). The eastern outskirts of the subtropics are occupied by subtropical variably humid (including monsoon) forests of evergreen deciduous and coniferous species, with an abundance of lianas and epiphytes. Red and yellow soils are formed under these forests.

The richest forests have survived in East Asia. They are characterized by a mixture of plants of different latitudes. Magnolia, lacquer tree and even palms and tree ferns grow alongside maple and birch trees. The fauna is also characterized by a mixture of species: lynx, maral, macaque, raccoon dog and the endangered panda. In the continental areas of the subtropics, there are zones of subtropical steppes, semi-deserts and deserts. In Asia, they have a mosaic distribution and occupy the largest areas in the south of Central Asia and in the inner parts of the highlands of Western Asia. Dry climate with hot summers and warm winter allows growing on gray soils and brown desert soils only drought-resistant grasses and shrubs (caragana, feather grass, wormwood, onions). Unique appearance of subtropical deserts North America attached to giant cacti (prickly pear and cereus), yucca and agave. The richest subtropical steppes are found in South America. On chernozem soils, forb-cereal meadows of wild lupine, pampas grass, feather grass grow.

The fauna of semi-deserts and deserts of the tropics and subtropics is represented by species that have adapted to high temperatures and lack of moisture. Ungulates (gazelles, mountain rams, antelopes) travel long distances in search of food and water. "Ship of the Desert" - a camel can be without food and water for a long time, storing them in its humps. Rodents dig holes: marmots, jerboas, ground squirrels. Scorpions, phalanxes, geckos, skinks, boas (sandy, steppe), snakes (vipers, rattlesnakes), monitor lizards live.

Natural zones are named according to their main distinguishing feature - vegetation cover. In equatorial and tropical latitudes, the largest areas are occupied by natural zones of humid equatorial forests, savannas and tropical deserts and semi-deserts. Forests form in the eastern oceanic regions of the tropics, and deserts and semi-deserts in the central continental and western oceanic currents washed by cold currents.