Natural areas of North America. "North America. Natural areas. Population Tropics and subtropics, mixed monsoon forests

The essay was completed by Gennady Osipik, 7th grade

Angarsk

Geographical position.

North America, like South America, lies in western hemisphere. The size of the territory is 24.2 million square km (including islands). It is inferior to Eurasia and Africa. North America lies in the subarctic, northern, temperate and subtropical zones.

The shores of the continent 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 twentieth century. North America is separated from Eurasia by the narrow Bering Strait. In the past, at the site of the strait there was an isthmus that connected North America with Eurasia, which determined the similarity of the flora and fauna of these continents.

From the history of the discovery of the continent.

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

Relief and minerals.

Plains. At the base of the plains of North America lies the ancient North American Plate. As a result of the subsidence and flooding of its northern part, the Canadian Arctic Archipelago and Greenland were formed. On northeast On the mainland there is a hill where the crystalline rocks of the platform (granites and gneisses) come to the surface. To the south of the hill extend Central Plains. Here's the foundation North American platform covered with thicknesses sedimentary rocks. The northern part of the continent, up to 40 degrees N, was subject to glaciation several times (the last glaciation ended 10-11 thousand years ago): here the glaciers, retreating, left sediments 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 sediments. Rivers flowing from the mountains cut the plains into deep valleys. To the south, the Central Plains merge into the Mississippian Lowland, composed of river sediments. The Mississippian lowland in the south merges with the coastal lowlands Gulf of Mexico And Atlantic Ocean. They were formed relatively recently as a result of the submergence of these land areas and the accumulation of sediment from rivers on the continental shallows.

Appalachia. In the east of the continent stretch the Appalachian Mountains.

Cordillera. Along the coast Pacific Ocean extends mountain system Cordillera. The Cordillera stretches in several parallel ridges. Some of them pass near the ocean, others retreat far to the east. The ridges diverge especially widely in the middle part. Here are located deep depressions, vast plateaus and highlands covered with solidified lava. The most significant of them are Big Pool and the Mexican Highlands.

Climate.

Reasons influencing the climate of North America.

Great length of the continent.

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

The influence of warm and cold currents

The influence of the Pacific Ocean.

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

The listed reasons determined the great diversity of the climate of North America.

Climatic zones and regions.

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

The subarctic zone is characterized by frosty winters and moderately cool summers. The amount of precipitation is low, snow cover in winter insignificant. Permafrost is widespread throughout summer months only a small amount thaws upper layer soil. Eastern, internal and western regions temperate zone The climate varies markedly. In the east of the region the climate is temperate continental, with frequent fogs on the coast.

In the subtropical zone, summers are hot and warm winter. However, intrusions of cold air masses from the north cause short-term frosts and snowfalls. The humid climate in the east of the belt gives way to continental in the middle and Mediterranean in the west.

In the east tropical zone The climate is tropical humid, while the interior parts of the Mexican Highlands and the California Peninsula have a tropical desert climate.

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

Natural areas.

In the north of the continent, natural zones stretch in stripes from west to east, while in the middle and southern parts they extend from north to south. Altitudinal zonation is evident in the Cordillera.

By species composition, plant and animal world The north of the continent 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 in the zone arctic deserts. Here, in places freed from snow and ice, mosses and lichens grow on poor rocky and marshy soils during the short and cool summer. In this zone since ice age there is a musk ox. The animal is covered with thick and long dark brown fur, which protects it well from the cold.

Tundra zone.

The northern coast of the mainland and the adjacent islands are occupied by a tundra zone. Southern border 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 residues decompose slowly. In addition, the frozen layer prevents the seepage of moisture, resulting in the formation of excess moisture. Therefore, peat bogs are widespread in the tundra. On the tundra-gley soils in the northern part of the tundra, mosses and lichens grow, and in the southern part - marsh grasses, wild rosemary shrubs, blueberry and blueberry bushes, low-growing birch, willow, and alder with curved trunks. The North American tundra is home to the arctic fox, polar wolf, reindeer caribou, white partridge etc. In summer a lot of people come here migratory birds. There are many seals and walruses in the coastal waters of the zone. Found on the northern coast of the mainland polar bear. In the west, in the Cordillera, mountain tundra extends far to the south. Increasingly appears to the south woody vegetation, 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 under humid and cool summer conditions, as a result of which minor plant litter slowly decomposes and produces a small amount of humus (up to 2%). Under a thin layer of humus lies a whitish layer with insoluble rock elements, the color of which resembles ash. Because of the color of this horizon, such soils are called podzolic. They grow mainly in the taiga coniferous trees– black spruce, balsam fir, pine, American larch; There are also deciduous ones - paper birch with smooth white bark, aspen. Found in the forests beasts of prey– 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 thick coniferous forests mainly from Sitka spruce, hemlock, and Douglas fir. Forests rise along the mountain slopes up to 1000-1500 m; higher they thin out and turn into mountain tundra. In the mountain forests there are bears - grizzlies, skunks, raccoons; there are a lot of rivers salmon fish, there are seal rookeries on the islands.

Mixed and deciduous forests.

South of the zone coniferous forests There are zones of mixed and broad-leaved, as well as variable humid 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 there are gray forest soils, under broad-leaved forests there are brown forest soils, and in the south under variable wet soils there are yellow soils and red soils. IN mixed forests yellow birch, sugar maple, beech, linden, white and red pine predominate. Broad-leaved forests are characterized by different kinds oaks, chestnut, plane and tulip trees.

Evergreen zone tropical forests.

The evergreen tropical forests in the southern 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 there is less precipitation, and herbaceous vegetation predominates 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, predominantly grasses, reaching a height of 1.5 m, are called prairies in North America. Woody vegetation is found in river valleys and in moist low areas. Closer to the Cordillera, there is even less rainfall and the vegetation becomes poorer; low grasses - Grama grass (grass) and buffalo 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 Cordillera, the Mexican Highlands and the Californian coast. Here, on gray and brown soils, there are thorny bushes, cacti and wormwood, and on saline soils, there are saltworts.

Zones of savannas and evergreen forests.

In Central America and on the slopes Caribbean Sea There are zones of savannas and evergreen forests.

Arctic deserts

Most of the Canadian Arctic Islands and Greenland.

Climate. Arctic. Negative or near-zero temperatures predominate.

Soils. Poor, rocky and swampy.

Vegetation. Mainly mosses and lichens.

Animal world. Muskox.

Tundra

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

Climate. Predominantly subarctic (partially arctic).

Soils. Tundra - gley, with excess moisture.

Vegetation. In the northern part there are mosses and lichens; in the southern part there are marsh grasses, blueberries and blueberries, wild rosemary bushes, low-growing willows, birches, and alders. Woody vegetation appears to the south.

Animal world. Polar wolf, caribou reindeer, arctic fox, ptarmigan and some others. A variety of migratory birds. In coastal waters there are seals and walruses. On the northern coast there is a polar bear.

Taiga

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

Climate. Moderate (with increased moisture).

Soils. Podzolics predominate.

Vegetation. Mainly coniferous trees - balsam fir, black spruce, pine, sequoias, American larch. Hardwoods - paper birch, aspen. On the slopes of the Cordillera there are Sitka spruce and Douglas fir.

Animal world. Wolves, bears, deer and elk, foxes, lynxes, sables, beavers, muskrats. In mountain forests there are skunks, grizzly bears, and raccoons. In the rivers there are salmon fish. There are seal rookeries on the islands.

Mixed and broad-leaved forests

South of the tundra zone. (In the eastern part of the North American continent, the predominance is variable rain forests).

Climate. Temperate, turning into subtropical.

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

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

Animal world. Wapiti deer, bears (grizzly), moose, lynx, wolves, wolverines, raccoons, hares, foxes.

Evergreen tropical forests

In the south of the Atlantic and Mississippian and lowlands.

Climate. Subtropical.

Soils. Gray - 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, forest gray.

Vegetation. Tall perennial grasses: wheatgrass, feather grass, etc. In river valleys there is woody vegetation. Near the Cordillera there are low cereal grasses (Gram grass and buffalo 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 (arid).

Soils. Brown and gray desert.

Vegetation. Black wormwood; on salt licks - quinoa solyanka; thorny bushes, cacti.

Animal world. Scarce.

Savannas and evergreen forests

On the slopes of the Caribbean and Central America.

Climate. There is a distinct change between dry and wet seasons.

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

Vegetation. Tropical types of hard-leaved grasses. 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 United States and Canada), natural zones replace each other in latitude, and to the south - meridionally. The following natural areas are represented in North America:

1. Arctic desert zone. This zone contains Greenland and most of the islands of the Canadian Arctic Archipelago. Here, in places freed from snow and ice, mosses and lichens grow on poor rocky and marshy soils during the short and cool summer.

2. Tundra zone. Occupies the northern coast of North America and the 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. In the northern part of the tundra mosses and lichens grow, and in the southern part there are marsh grasses, rosemary bushes, blueberry and blueberry bushes, low-growing birch, willow, and alder with curved trunks. The North American tundra is home to arctic fox, arctic wolf, caribou reindeer, ptarmigan, etc. In summer, many migratory birds fly here. There are many seals and walruses in the coastal waters of the zone. Polar bears are found on the northern coast of the mainland.

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. Mostly coniferous trees grow in the taiga - black spruce, balsam fir, pine, American larch; There are also deciduous ones - paper birch with smooth white bark, aspen. In the forests there are predatory animals - bears, wolves, lynxes, foxes; there are deer, elk and valuable fur-bearing animals - sable, beaver, muskrat. There are a lot of salmon fish in the rivers, and seal rookeries are located on the islands.

4. Zone of mixed and deciduous forests starts south from the taiga. In the eastern part of the continent there are variable humid forests that extend all the way to the Gulf of Mexico. 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, sycamore and tulip trees.

5. Evergreen tropical 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 starts west of the forest zone. Herbaceous vegetation predominates 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 moist low areas. Closer to the Cordillera, there is even less rainfall 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, there are thorny bushes, cacti and wormwood, and on saline soils, there are saltworts.

8. Savanna and evergreen forest areas located in Central America and on the slopes of the Caribbean Sea.

North America is located in the western hemisphere of our planet. The total area of ​​the mainland (including islands) is 24.2 million km 2. North America is smaller than Eurasia or Africa. It lies in the subtropical, temperate, northern and subarctic zones. The waters of three oceans wash the continent. All this, combined with the relief, formed the natural areas of North America. Character traits each of them will be discussed below.

It should also be noted that the formation of natural zones was influenced by the gradual movement of heat from north to south. And when moving from east to west, dryness increases in the southern part of the continent. Characteristics of the natural zones of North America comes down to an analysis of their climate, average summer and winter temperatures, and amount of precipitation. They also pay attention to the composition of the soil, the types of plants and animals that can be found in the described area.

North America: natural areas of arctic deserts and tundra

The first zone (Arctic deserts) occupies most Canadian Arctic Archipelago and Greenland. A huge area occupied by glaciers is located in the east of the zone. The western part is occupied by rocky Arctic deserts. Glaciers are practically lifeless space. Neither plants nor animals of the natural zones of North America live here. The exception may be some types of algae. In the rocky part you can find, in addition to algae, bacteria, mosses and crustose lichens. Also on land live lemmings - polar mice, which feed on wolves and arctic foxes.

The tundra zone of the mainland is located in the subarctic climatic zone. It is quite similar to the Asian or European tundra. Soils and soils are characterized by widespread waterlogging due to big amount precipitation and low temperatures. There are quite a lot of rivers, lakes and swamps in this area. On peat-gley soils you can find grasses such as cassiopeia, forget-me-nots, polar poppies, and cotton grass. Dwarf birches, wild rosemary and willows also grow here. Huge areas are covered with lichens and mosses. Among the animals you can find wolves, arctic foxes, lemmings, musk oxen and caribou.

Forest-tundra and taiga zones

Compared to Eurasia, the forest-tundra here is more colorful and diverse. The river valleys located closer to the south are covered with forests. The northern border is home to spruce (white and black), mosses and lichens. In the western part you can see larch, but in Labrador you can see balsam fir. The forest-tundra zone extends for 500 km.

North America, whose natural zones are largely located in the temperate climate zone, can boast of a zone of coniferous forests stretching from the Atlantic coast in the east to the Pacific coast in the west. There are a lot of swamps here. The vegetation cover consists primarily of balsam fir, white spruce, and black spruce, but paper birch, American larch, and several species of pine trees can also be found. The trees here are powerful, their height is often 70-100 meters. Animals in the taiga include wood bison, American elk, several species of bears (grizzly, baribal), as well as red fox, raccoon, muskrat, skunk, and beaver.

North America: natural areas of mixed and broadleaf forests

The first of these zones occupies the territory of the Great Lakes. Here, tracts of coniferous trees are wonderfully combined with small-leaved species (poplar, birch) and deciduous forests. The soils are brown forest and soddy-podzolic. Here you can find several types of maple (silver, red, sugar), beech, oak, linden, elm, ash. Coniferous species include pine, thuja, fir, larch, and spruce.

Broadleaf (Appalachian) forests are located on the south and southeast sides of mixed forests. The main forest-forming species of this natural zone are oak (large-fruited, red and white), chestnut, beech, and linden. Magnolias, black walnuts and hickories can be found here. The diversity of vegetation is complemented by vines, forbs and dense undergrowth. This wealth of broadleaf forests is associated with fertile brown forest soils. As for the animal world, it has been preserved only in protected areas, in nature reserves, in which North America is rich.

Natural areas of forest-steppe and prairie

The prairies are located on the territory of the Central and Great Plains, just south of the taiga. They occupy part of the Central Plains (western). They are treeless plains covered with tall grass and cereal vegetation. 80% of the entire plant world is made up of small and blue bearded vultures. The latter reaches 1.8 m in height. This is due to the chernozem-like soils of this subzone. This area has now become one of the main agricultural areas of the United States, where corn is grown. The forest-steppe subzone runs from west to east across the Great Plains. Vegetable world represented mainly by small aspen groves and meadows (fescue, wheatgrass, reed grass). The soils are meadow-chernozem and gray forest.

Zones of steppes, deserts and semi-deserts

The steppe is quite heterogeneous. This zone receives on average up to 600 mm of annual precipitation. The black soil plains are overgrown with fescue, wheatgrass and bearded grass. This area is almost completely plowed and cut up by ravines and gullies. The dry part of the steppes receives up to 400 mm of precipitation per year, which, together with soils with low humus content, does not produce high yields.

Deserts and semi-deserts occupy the driest areas of the Columbia Plateau, as well as the bulk of the Great Basin. No more than 250 mm of precipitation falls here per year. The main vegetation on gray-brown soils is wormwood; quinoa grows on saline soils.

Tropics and subtropics, mixed monsoon forests

The tropical zone has a lot of heat. Natural zones change from east to west, which is associated with different moisture levels in the areas. Monsoon forests grow in the southeast of the subtropical zone, on red and yellow earth soils. In addition to coniferous trees, you can see dwarf palms, evergreen oaks and shrubs, and magnolias intertwined with vines. Cypress trees grow in the swamps, and sabal palms and pine trees grow in drier areas. A huge number of birds, turtles and alligators live here.

Also in North America there is a narrow strip of hard-leaved forests and shrubs and zones altitudinal zone. For clarity, it is better to put all the information provided in a table, analyzing the natural zones of North America. The table will help organize the information and knowledge received. Generalized material will also be more convenient for memorization.

The essay was completed by Gennady Osipik, 7th grade

Angarsk

Geographical position.

North America, like South America, lies in the Western Hemisphere. The size of the territory is 24.2 million square km (including islands). It is inferior to Eurasia and Africa. North America lies in the subarctic, northern, temperate and subtropical zones.

The shores of the continent 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 shipping canal was dug at the beginning of the 20th century. North America is separated from Eurasia by the narrow Bering Strait. In the past, at the site of the strait there was an isthmus that connected North America with Eurasia, which determined the similarity of the flora and fauna of these continents.

From the history of the discovery of the continent.

Long before Columbus, at the end of the 10th century, the Norman Eirik Rowdy 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. The Normans lived in the south and southwest of Greenland for several centuries. Later they visited the northeastern shores of North America. In the late 15th century, Europeans rediscovered Newfoundland and Labrador and then the east coast of the mainland. At the beginning of the 16th century, detachments of 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 North American Plate. As a result of the subsidence and flooding of its northern part, the Canadian Arctic Archipelago and Greenland were formed. In the northeast of the continent there is a hill where the crystalline rocks of the platform (granites and gneisses) come to the surface. To the south of the highlands lie the Central Plains. Here the foundation of the North American platform is covered with sedimentary rocks. The northern part of the continent, up to 40 degrees N, was subject to glaciation several times (the last glaciation ended 10-11 thousand years ago): here the glaciers, retreating, left sediments 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 sediments. Rivers flowing from the mountains cut the plains into deep valleys. To the south, the Central Plains merge into the Mississippian Lowland, composed of river sediments. The Mississippian lowland in the south merges with the coastal lowlands of the Gulf of Mexico and the Atlantic Ocean. They were formed relatively recently as a result of the submergence of these land areas and the accumulation of sediment from rivers on the continental shallows.

Appalachia. In the east of the continent stretch the Appalachian Mountains.

Cordillera. The Cordillera mountain system stretches along the Pacific coast. The Cordillera stretches in several parallel ridges. 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.

Reasons influencing the climate of North America.

Great length of the continent.

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

The influence of warm and cold currents

The influence of the Pacific Ocean.

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

The listed reasons determined the great diversity of the climate of North America.

Climatic zones and regions.

Arctic air masses dominate in the Arctic belt throughout the year. Severe winters are accompanied by frequent snowstorms, and cold summers are accompanied by constant fog 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 and snow cover in winter is insignificant. Permafrost is widespread throughout, with only a small top layer of soil thawing in the summer months. The eastern, internal and western regions of the temperate zone differ markedly in climate. In the east of the region the climate is temperate continental, with frequent fogs on the coast.

The subtropical zone has hot summers and warm 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 gives way to continental in the middle and Mediterranean in the west.

In the east of the tropical zone the climate is tropical humid, while in the interior parts 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 continent, natural zones stretch in stripes from west to east, while in the middle and southern parts they stretch from north to south. Altitudinal zonation is evident in the Cordillera.

In terms of species composition, the flora and fauna of the north of the continent are 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 rocky and marshy soils during the short and cool summer. The musk ox has been found in this area since the Ice Age. The animal is covered with thick and long dark brown fur, which protects it well from the cold.

Tundra zone.

The northern coast of the mainland and the adjacent islands are occupied by a 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 residues decompose slowly. In addition, the frozen layer prevents the seepage of moisture, resulting in the formation of excess moisture. Therefore, peat bogs are widespread in the tundra. On the tundra-gley soils in the northern part of the tundra, mosses and lichens grow, and in the southern part - marsh grasses, wild rosemary shrubs, blueberry and blueberry bushes, low-growing birch, willow, and alder with curved trunks. The North American tundra is home to arctic fox, arctic wolf, caribou reindeer, ptarmigan, etc. In summer, many migratory birds fly here. There are many seals and walruses in the coastal waters of the zone. Polar bears are found on the northern coast of the mainland. In the west, in the Cordillera, 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 under humid and cool summer conditions, as a result of which minor plant litter slowly decomposes and produces a small amount of humus (up to 2%). Under a thin layer of humus lies a whitish layer with insoluble rock elements, the color of which resembles ash. Because of the color of this horizon, such soils are called podzolic. Mostly coniferous trees grow in the taiga - black spruce, balsam fir, pine, American larch; There are also deciduous ones - paper birch with smooth white bark, aspen. In the forests there are predatory animals - bears, wolves, lynxes, foxes; there are deer, elk and valuable fur-bearing animals - sable, beaver, muskrat. The slopes of the Cordillera, facing the ocean, are covered with dense coniferous forests, mainly of Sitka spruce, hemlock, and Douglas fir. Forests rise along the mountain slopes up to 1000-1500 m; higher they thin out and turn into mountain tundra. In the mountain forests there are bears - grizzlies, skunks, raccoons; There are a lot of salmon fish in the rivers, and seal rookeries are located on the islands.

Zones of mixed and deciduous forests.

To the south of the coniferous forest zone there are zones of mixed and broad-leaved, as well as variable humid 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 there are gray forest soils, under broad-leaved forests there are brown forest soils, and in the south under variable wet soils there are yellow soils and red soils. 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, sycamore and tulip trees.

Zone of evergreen tropical forests.

The evergreen tropical forests in the southern 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 there is less precipitation, and herbaceous vegetation predominates 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 moist low areas. Closer to the Cordillera, there is even less rainfall and the vegetation becomes poorer; low grasses - Grama grass (grass) and buffalo 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 Cordillera, the Mexican Highlands and the Californian coast. Here, on gray and brown soils, there are thorny bushes, cacti and wormwood, and on saline soils, there are saltworts.

Zones of savannas and evergreen forests.

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

Altitudinal zone best expressed in the Cordillera, its features are determined by the height of the mountains and their position individual parts in different climatic zones.