"North America. natural areas. Population. Natural areas of North America Forest-tundra and taiga zones

Natural areas of North America

The abstract was prepared by Osipik Gennady, 7 "G" class

G. Angarsk

Geographical position.

North America, like South America, lies in the Western Hemisphere. In terms of territory - 24.2 million square kilometers (with islands). - It is inferior to Eurasia and Africa. North America lies in the subarctic, northern, temperate and subtropical zones.

The shores of the mainland are washed by the waters of three oceans (Pacific, Atlantic, Arctic). In the south, it is connected by the narrow Isthmus of Panama to South America, through which a navigable sea canal was dug at the beginning of the 20th century. North America is separated from Eurasia by the narrow Bering Strait. In the past, there was an isthmus at the site of the strait, connecting North America with Eurasia, which determined the similarity of the flora and fauna of these continents.

From the history of the discovery of the mainland.

Long before Columbus, at the end of the 10th century, the Norman Eirik Raudi, with several companions, set off from Iceland to the west, reaching a previously unknown land - Greenland. Here, in the harsh conditions of the north, the Normans created settlements. For several centuries the Normans lived in the south and southwest of Greenland. Later they visited the northeastern shores of North America. At the end of the 15th century, Europeans rediscovered Newfoundland, Labrador, and then the east coast of the mainland. At the beginning of the 16th century, detachments of the Spanish conquerors, led by Cortes, captured Mexico and some lands of Central America.

Relief and minerals.

Plains. At the base of the plains of North America lies the ancient N American Platform. As a result of the sinking and flooding of its northern part, the Canadian Arctic Archipelago and Greenland were formed. In the northeast of the mainland, there is a hill where crystalline rocks of the platform (granites and gneisses) come to the surface. South of the highlands stretch the Central Plains. Here, the basement of the North American Platform is covered with sedimentary rocks. The northern part of the mainland, up to 40 degrees N, was subjected to glaciation several times (the last glaciation ended 10-11 thousand years ago): here the glaciers, retreating, left deposits of clay, sand and stones. In the western part of the North American Platform, along the Cordillera, the Great Plains stretch in a wide strip, composed of thick marine and continental deposits. Rivers flowing from the mountains cut the plains with deep valleys. To the south, the Central Plains turn into the Mississippi Lowland, composed of river sediments. The Mississippi Lowlands merge in the south with the coastal lowlands of the Gulf of Mexico and the Atlantic Ocean. They were formed relatively recently as a result of the subsidence of these land areas and the accumulation of sediments from rivers on the continental shelf.

Appalachians. In the east of the mainland, the Appalachian Mountains stretch.

Cordillera. The Cordillera mountain range extends along the Pacific coast. The Cordillera stretched out in several parallel ranges. Some of them pass near the ocean, others retreat far to the east. The ridges diverge especially widely in the middle part. There are deep depressions, vast plateaus and highlands covered with solidified lava. The most significant of them are the Great Basin and the Mexican Highlands.

Climate.

Causes influencing the formation of the climate of North America.

Great length of the mainland.

Prevailing winds (northeast south of 30 degrees N.W. and westerlies in temperate latitudes).

Influence of warm and cold currents

Influence of the Pacific Ocean.

Flat terrain in the middle part of the mainland (does not interfere with the movement of air masses).

These reasons have determined the great diversity of the climate of North America.

Climatic zones and regions.

Arctic air masses dominate throughout the year in the Arctic belt. Severe winters are accompanied by frequent snowstorms, and cold summers are accompanied by constant fogs and cloudy weather. The largest area of this belt (Greenland and some other islands) is covered with glaciers.

The subarctic zone is characterized by frosty winters and moderately cool summers. Precipitation is low, snow cover is negligible in winter. Permafrost is ubiquitous, with only a small top layer of soil thawing in the summer months. The eastern, inner and western regions of the temperate zone differ markedly in climate. In the east of the region the climate is temperate continental, fogs are frequent on the coast.

The subtropical zone has hot summers and mild winters. However, intrusions of cold air masses from the north cause short-term frosts and snowfalls. The humid climate in the east of the belt is replaced by continental in the middle part and Mediterranean in the west.

In the east of the tropical belt, the climate is tropical humid, while in the interior of the Mexican Highlands and the California Peninsula, the climate is tropical desert.

The extreme south of North America lies in the subequatorial belt. There is a lot of rainfall and high temperatures throughout the year.

natural areas.

In the north of the mainland, natural zones stretch in strips from west to east, while in the middle and southern parts they stretch from north to south. In the Cordillera, altitudinal zonation is manifested.

In terms of species composition, the flora and fauna of the north of the mainland is similar to Northern Eurasia, and the south is similar to South America, which is explained by their territorial proximity and common development.

Arctic desert zone.

Greenland and most of the islands of the Canadian Arctic Archipelago are located in the Arctic desert zone. Here, in places freed from snow and ice, mosses and lichens grow on poor stony and swampy soils during a short and cool summer. The musk ox has been found in this zone since the Ice Age. The animal is covered with thick and long dark brown hair, which protects it well from the cold.

Tundra zone.

The northern coast of the mainland and the islands adjacent to it is occupied by the tundra zone. The southern border of the tundra in the west lies near the Arctic Circle, and as it moves east, it enters more southern latitudes, capturing the coast of Hudson Bay and the northern part of the Labrador Peninsula. Here, under conditions of short and cool summers and permafrost, tundra soils are formed, in which plant remains decompose slowly. In addition, the frozen layer prevents the infiltration of moisture, resulting in its excess. Therefore, peat bogs are widespread in the tundra. Mosses and lichens grow on tundra-gley soils in the northern part of the tundra, and marsh grasses, rosemary shrubs, blueberry and blueberry shrubs, undersized birch trees with curved trunks, willows, and alder grow in the southern part. Arctic fox, polar wolf, caribou reindeer, ptarmigan, etc. live in the North American tundra. In summer, many migratory birds arrive here. There are many seals and walruses in the coastal waters of the zone. On the northern coast of the mainland there is a polar bear. In the west, in the Cordillera, the mountain tundra extends far to the south. To the south, woody vegetation appears more and more often, the tundra gradually turns into forest-tundra, and then into coniferous forests or taiga.

Taiga zone.

The taiga zone extends in a wide strip from west to east. Podzolic soils predominate here. They are formed in humid and cool summers, as a result of which insignificant plant litter slowly decomposes and gives a small amount of humus (up to 2%). Under a thin layer of humus lies a whitish layer with insoluble elements of the rock, resembling ash in color. For the color of this horizon, such soils are called podzolic. In the taiga, mainly coniferous trees grow - black spruce, balsam fir, pine, American larch; there are also deciduous ones - paper birch with smooth white bark, aspen. There are predatory animals in the forests - bears, wolves, lynxes, foxes; there are deer, elk and valuable fur animals - sable, beaver, muskrat. The slopes of the Cordillera, facing the ocean, are covered with dense coniferous forests, mainly from Sitka spruce, hemlock, Douglas fir. Forests rise up the mountain slopes up to 1000-1500 m, above they thin out and pass into the mountain tundra. Bears live in mountain forests - grizzlies, skunks, raccoons; there are a lot of salmon fish in the rivers, there are seal rookeries on the islands.

Zones of mixed and broad-leaved forests.

To the south of the zone of coniferous forests, there are zones of mixed and broad-leaved, as well as variable moist forests. They are located only in the eastern part of the mainland, where the climate is milder and more humid, reaching in the south to the Gulf of Mexico. Under mixed forests in the north, gray forest soils are common, under broad-leaved forests, brown forest soils, and in the south, under variable wet ones, yellow and red soils. The mixed forests are dominated by yellow birch, sugar maple, beech, linden, white and red pine. Broad-leaved forests are characterized by various types of oaks, chestnut, plane tree and tulip tree.

Tropical evergreen forest zone.

The evergreen rainforests in the south of the Mississippi and Atlantic lowlands consist of oaks, magnolias, beeches and dwarf palms. The trees are entwined with vines.

Forest steppe zone.

To the west of the forest zone, precipitation is less and herbaceous vegetation prevails here. The forest zone passes into the zone of forest-steppes with chernozem-like soils and steppes with humus-rich chernozems and chestnut soils. Steppes with tall grasses, mainly cereals, reaching a height of 1.5 m, are called prairies in North America. Woody vegetation is found in river valleys and in humid lowlands. Closer to the Cordillera, precipitation is even less and the vegetation becomes poorer; low grasses - Gram grass (grass) and bison grass (perennial grass only 10-30 cm high) - do not cover the entire ground and grow in separate bunches.

Desert and semi-desert zone.

Semi-deserts and deserts occupy a significant part of the interior plateaus of the Cordilleras, the Mexican Highlands and the Californian coast. Here, on gray and brown soils, thorny shrubs, cacti and wormwood, and on saline soils - saltwort.

Savannahs and evergreen forests.

In Central America and on the slopes of the Caribbean Sea there are zones of savannahs and evergreen forests.

Arctic deserts

Most of the Canadian Arctic Islands and Greenland.

Climate. Arctic. Negative or close to zero temperatures prevail.

Soils. Poor, rocky and marshy.

Vegetation. Mostly mosses and lichens.

Animal world. Musk ox.

Tundra

Northern coast of the mainland with adjacent islands. To the east - the coast of Hudson Bay and the northern part of the Labrador Peninsula.

Climate. The subarctic (partially arctic) prevails.

Soils. Tundra - gley, with excess moisture.

Vegetation. In the northern part - mosses, lichens; in the southern part - swamp grasses, blueberries and blueberries, wild rosemary bushes, undersized willows, birches, alders. Woody vegetation appears to the south.

Animal world. Arctic wolf, caribou reindeer, arctic fox, ptarmigan and some others. Diversity of migratory birds. In coastal waters - seals and walruses. On the northern coast - a polar bear.

Taiga

It stretches in a wide strip from east to west. Impenetrable coniferous forests.

Climate. Moderate (with increased moisture).

Soils. Podzolic prevail.

Vegetation. Mostly coniferous trees - balsam fir, black spruce, pine, sequoia, American larch. From hardwoods - paper birch, aspen. On the slopes of the Cordillera - Sitka spruce, Douglas fir.

Animal world. Wolves, bears, deer and elks, foxes, lynxes, sables, beavers, muskrats. In the mountain forests - skunks, bears (grizzlies), raccoons. In the rivers - salmon fish. On the islands - rookeries of fur seals.

Mixed and deciduous forests

south of the tundra zone. (Variably humid forests predominate in the eastern part of the North American continent).

Climate. Moderate to subtropical.

Soils. Gray forest soils, brown forest soils, yellow soils and red soils.

Vegetation. In mixed forests - sugar maple, yellow birch, white and red pine, linden, beech. In deciduous forests - different types of oaks, sycamore, chestnut, tulip tree.

Animal world. Elk deer, bears (grizzlies), elks, lynxes, wolves, wolverines, raccoons, hares, foxes.

evergreen tropical forests

In the south of the Atlantic and Mississippi and lowlands.

Climate. Subtropical.

Soils. Grey-brown, brown.

Vegetation. Oaks, magnolias, beeches, dwarf palms. The trees are entwined with vines.

Animal world. Diverse.

Forest-steppe

Treeless plains to the west of the forest zone. (In North America they are called prairies).

Climate. Subtropical.

Soils. Chernozems: podzolized and leached. Chestnut, gray forest.

Vegetation. High perennial grasses: wheatgrass, feather grass, etc. In the river valleys - woody vegetation. Near the Cordillera - low cereal grasses (Gram grass and bison grass).

Animal world. Diverse and rich.

Desert and semi-desert zone

A significant part of the California coast, the Mexican highlands and the interior plateaus of the Cordillera.

Climate. Moderate (dry).

Soils. Brown and gray desert.

Vegetation. Black wormwood; on salt licks - quinoa saltwort; thorny shrubs, cacti.

Animal world. Scarce.

Savannahs and evergreen forests

On the slopes of the Caribbean and in Central America.

Climate. The change of dry and wet seasons is distinct.

Soils. Black, red-brown, brown, gray-brown

Vegetation. Tropical types of hard-leaved cereals. Trees with a long root system and umbrella-shaped crowns predominate.

Animal world. Versatile.

natural areas of North America.

Up to the latitude of the Great Lakes (the border of the USA and Canada), natural zones replace each other in latitude, and to the south - meridional. The following natural areas are represented in North America:

1. Arctic desert zone. Greenland and most of the islands of the Canadian Arctic Archipelago are located in this zone. Here, in places freed from snow and ice, mosses and lichens grow on poor stony and swampy soils during a short and cool summer.

2. tundra zone. It occupies the northern coast of North America and adjacent islands. The southern border of the tundra in the west lies near the Arctic Circle, and as it moves east, it enters more southern latitudes, capturing the coast of Hudson Bay and the northern part of the Labrador Peninsula. Here, in conditions of short and cool summers and permafrost, peat bogs are widespread. Mosses and lichens grow in the northern part of the tundra, and marsh grasses, wild rosemary shrubs, blueberry and blueberry shrubs, undersized birches with twisted trunks, willows, and alders grow in the southern part. Arctic fox, polar wolf, caribou reindeer, ptarmigan, etc. live in the North American tundra. In summer, many migratory birds arrive here. There are many seals and walruses in the coastal waters of the zone. On the northern coast of the mainland there is a polar bear.

3. Taiga zone. To the south, the tundra gradually turns into forest-tundra, and then into coniferous forests or taiga. The taiga zone extends in a wide strip from west to east. In the taiga, mainly coniferous trees grow - black spruce, balsam fir, pine, American larch; there are also deciduous ones - paper birch with smooth white bark, aspen. There are predatory animals in the forests - bears, wolves, lynxes, foxes; there are deer, elk and valuable fur animals - sable, beaver, muskrat. There are a lot of salmon fish in the rivers, there are rookeries of fur seals on the islands.

4. Zone of mixed and deciduous forests starts south of the taiga. In the eastern part of the mainland, variable rainforests are located, which reach right up to the Gulf of Mexico zone. The mixed forests are dominated by yellow birch, sugar maple, beech, linden, white and red pine. Broad-leaved forests are characterized by various types of oaks, chestnut, plane tree and tulip tree.

5. Tropical evergreen forest zone located in the south of the Mississippi and Atlantic lowlands. The forests consist of oaks, magnolias, beeches and dwarf palms. The trees are entwined with vines.

6. Forest steppe zone begins to the west of the forest zone. Herbaceous vegetation prevails here. Steppes with tall grasses, mainly cereals, reaching a height of 1.5 m, are called prairies in North America. Woody vegetation is found in river valleys and in humid lowlands. Closer to the Cordillera, precipitation is even less and the vegetation becomes poorer; low grasses do not cover the entire ground and grow in separate bunches.

7. Desert and semi-desert zone occupies a significant part of the interior plateaus of the Cordillera, the Mexican Highlands and the Californian coast. Here, on gray and brown soils, thorny shrubs, cacti and wormwood, and on saline soils - saltwort.

8. Savannah and evergreen forest zones located in Central America and on the slopes of the Caribbean.

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The climate of the northern continents is very similar, but there are some differences. North America has less harsh conditions than similar areas in Russia. This is primarily due to the fact that the natural zones themselves are located to the south.

How zonation is traced in North America

Zoning in North America can be clearly seen in latitudes. Starting from the Great Lakes and south, the mixing of nature occurs in a vertical direction - from West to East up to the Rocky Mountains. This is due to uneven moistening under the action of oceanic air masses.

The natural zones of North America have characteristic features of both Eurasia (in northern latitudes) and South America (in southern latitudes).

Rice. 1. Map of the natural zones of North America

Let us consider a more detailed description of the natural zones of this continent using the table.

Table "Natural areas of North America"

Zone name	Geographic location		Vegetable world	Animal world
Arctic deserts	Canadian archipelago	Stony, permafrost zone	Moss, lichen	Lemming, arctic fox, musk ox
	Northern arctic climate zone	Podzolic, permafrost-taiga	Moss, lichen, shrub, grass	Black grizzly bear, elk, wood bison, lynx, skunk, muskrat
forest tundra	Very narrow band in northern latitudes	Gley, podzolic	Balsam fir, black and white spruce, pine	wolf, lemming
Mixed and broad-leaved forests	Corresponds to the temperate climate zone	Brown forest, sod-podzolic	Maple, beech, yellow birch, tulip tree, red pine	Bison, brown bear, lynx.
Forest-steppes and steppes	Prairies - the central part is closer to the mountains	Chernozems, chestnut	Cereals, bison grass, fescue	Coyote, rodents, rabbit, prairie dog
Variable rainforests	Subtropical climate zone	Yellow soils and red soils	Oak, magnolia, palm, cypress	Wild animals are exterminated
Semi-deserts and deserts	Interior of the Cordillera	Gray-brown, gray soils	Wormwood, saltwort, cactus, agave	Reptiles, rodents, armadillo
Tropical savannas and tropical rainforests	Central America	Krasnozems and red-brown	Plantations of tropical crops	Wild animals are exterminated

Characteristics of natural areas

The forest zone is about a third of the mainland. The most common are mixed and broad-leaved. In North America (in Canada), taiga tree species predominate. The forest zone is replaced by steppes.

What have we learned?

The natural areas of North America have some features compared to Eurasia. The change of belts here takes place in more southern latitudes, so the climate is milder here. Not only horizontal, but also vertical zonality is traced, which is a consequence of the influence of oceanic air masses.

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North America is located within all, with the exception of, geographical zones. Each of them includes several natural zones. The greatest natural diversity is moderate.

In the north of the mainland, latitudinal zonality is clearly manifested: natural zones are elongated along the parallel and replace each other in latitude. The main reason for the pronounced latitude is the flatness of the territory of this part of the mainland and, in connection with this, a gradual increase from north to south in the amount of solar heat entering the Earth's surface.

To the south, natural zones are elongated meridionally, and replace each other as they move away from the coasts. This is due to the fact that the mountain barriers, meridionally extended along the western and eastern coasts, do not allow the Pacific and Atlantic to freely penetrate deep into the continent. Therefore, the change (and hence the natural zones) occurs in two directions: from north to south and from the ocean margins to the interior of the mainland.

Natural zones of the arctic and geographical zone. Arctic deserts occupy the Northern Islands. Cold and abundance of precipitation contribute to the development of glaciation. In summer, mosses, lichens, cold-resistant grasses and shrubs appear in depressions and cracks. Arctic soils contain almost no organic matter. The life of representatives of the animal world is connected with the sea, which provides food. Bird colonies are typical on the islands. Seals, walruses, whales live in the waters of the seas. Polar bears, wolves, arctic foxes enter the coastal regions from the mainland. In Greenland and the Canadian Arctic Archipelago, the largest mammal lives - the musk ox, or musk ox.

Tundra and occupy the north of the mainland. Permafrost is widespread. In the north - in the Arctic - in the moss and lichen one can occasionally find grasses (sedge, cotton grass) and polar flowers - forget-me-nots, polar poppies, dandelions.

To the south, in the subarctic zone, the tundra becomes shrubby: low-growing dwarf birch and willow, wild rosemary, blueberries, blueberries appear. Due to waterlogging caused by summer thaw, tundra-gley soils form in the tundra. To the south, along the river valleys, trees appear - black and white spruce, and the forest-tundra begins.

Tundra vegetation provides food for a variety of animals: reindeer, polar hares, lemmings. Small animals are hunted by a polar bear, a polar wolf, a polar fox. There are a white partridge, a predatory polar owl, in the summer waterfowl arrive - geese and ducks.

The temperate geographical zone occupies more than 1/3 of the mainland area. The climate is distinguished by the presence of contrasting seasons - warm summers and frosty winters. The taiga is represented by dark coniferous forests of black and white spruce and balsam fir. In dry places, pines grow: white (Weymouth), Banksa (stone) and red. Podzolic and gray forest soils are characteristic of the taiga, and peat-bog soils in the lowlands. The coniferous forests of the Pacific coast grow in conditions of abundant moisture, which is why they are called "rain forests".

Whole thickets in these forests form shrubs, sometimes thorny, grasses and ferns; mosses cover trunks, soil, hang from branches with long "beards". Due to the dense layer of forest floor, seeds rarely fall into the ground, so young trees grow directly on the trunks of rotting predecessors.

In the dense forest stands out the world's giants. This is the Douglas fir, or Douglas, and the evergreen sequoia, or "redwood", which forms the densest forest in the world. The height of these giants reaches 115 m. Mountain brown forest soils form under the rainforests. Because of the valuable wood, the forests are heavily cut down.

The fauna of the taiga is diverse. There are many large ungulates here: wapiti deer, moose; in the mountains there are bighorn goats and bighorn sheep. There are brown and black American bears; - gray and red squirrel, chipmunk; predators - puma (or cougar), marten, wolf, Canadian lynx, ermine, wolverine, fox; on the banks of the rivers - beaver, otter and musky rat (muskrat). Numerous birds - crossbills, warblers. One of the largest animals of the continent - the inhabitant of the "rain forests" - the grizzly bear. The length of its body can exceed 2.5 m.

In the eastern part of the mainland, winters are warmer, so deciduous trees appear among coniferous trees: elm, beech, linden, oak, birch. The taiga is replaced by a zone of mixed and broad-leaved forests. They occupy the vicinity of the Great Lakes and the Appalachians. Especially diverse in these forests are maples - sugar, red, silver. Closer to the coast, broad-leaved forests become dominant. They are distinguished by their antiquity and richness of species composition: oaks, chestnuts, beeches, hickory tree, deciduous magnolia, yellow poplar, black walnut, tulip tree. The decomposition of falling leaves leads to the accumulation of organic matter in the soil. Therefore, sod-podzolic soils are formed under them, and fertile brown forest soils are formed under broad-leaved ones.

The fauna of the forests used to be distinguished by its unique richness. Its typical representatives are: virginian deer, gray fox, lynx, baribal black bear, tree porcupine, American mink, weasel, badger, raccoon. Among the endemics there are flying squirrels, skunks, the only marsupials in North America - possums. Diverse birds, many snakes, freshwater turtles and amphibians.

The natural zonality of North America is characterized by: the presence of several natural zones within each geographical zone; change of natural zones within the belts: to the north - in latitude: from north to south, south of the 45th parallel - meridional: from the coasts to the center of the mainland; a wide range of natural zones in the temperate geographical zone.