Mysterious gaps in the Yamal tundra. Vegetation of arctic deserts and tundra. Geographical position. Brief description of cracks and landslides in the tundra of Canada why

Polar bioclimatic belt characteristic of the Arctic and Antarctic regions. The main geographical indicator is that the sum of positive temperatures does not exceed 800С. The polar belt is represented by two zones: polar desert zone and tundra zone .

Polar Desert Zone

In the Northern Hemisphere, the Arctic desert zone includes the northern islands of the Arctic Ocean (Franz Josef Land, Severnaya Zemlya, de Long islands, north of the New Siberian Islands) and the northern tip of the Taimyr Peninsula. The Arctic zone of polar deserts also covers the northern coast of Greenland, some of the islands of the North American archipelago. Polar deserts are also widespread in the high-latitude regions of Antarctica, free from ice cover.

The zone of the polar arctic deserts is distinguished by the exceptional severity of nature and the dryness of the climate. Large areas are covered with glaciers. The Arctic desert actually spreads over glacier-free spaces. Here, with a sharp lack of atmospheric moisture (50-100 mm), processes of frost weathering vigorously proceed. The soil cover is practically absent. Fragments of soils: ferruginous films on a rocky surface, a few millimeters of an organo-mineral mixture under crusty lichens, sometimes salt efflorescence, carbonate content of surface sediments.

In phytocenoses, there is a weak participation of terrestrial vegetation, which in places forms a closed cover in depressions of the relief and in shelters protected from the wind. However, in most of the elevated relief elements, the vegetation cover is very sparse, the soil surface is often covered with a crushed stone shell, among which individual low-growing plants, mainly lichens, nestle. There is no need to talk about a stable animal world. There are no reindeer or lemmings in Franz Josef Land. But in the summer seabird colonies nest, forming “bird colonies”. They are formed by puffins, puffins, gulls, auk and other birds. The life of most animals is associated with the ocean: walruses, seals, polar bears, sea otters, etc. In addition, there are lemmings, arctic foxes and some other animals.

In Antarctica, landscapes not covered with ice are called oases ... Bioclimatic conditions are more intense than in the Arctic. The vegetation of the oases is very sparse: most of the surface of the rocks and fine-earth sediments is exposed. Various types of crustaceous and bushy lichens and lithophilic mosses settle in places on the rocks, mosses are much more common on a fine earthy substrate. In cracks in rocks and on a fine earthy substrate, the flora of green and blue-green algae is abundant.

Penguin settlements and seal rookeries in the coastal and insular parts of Antarctica are especially abundantly populated with lichens and mosses. Since penguins and seals feed in the sea, the places of their long-term settlements are enriched with organic matter and mineral chemical elements of marine origin.

There are no terrestrial mammals in Antarctica. On the coast, in addition to various species of seals, more than 10 species of birds live: penguins, petrels, skuas, etc.

Thus, in glacial (ice) deserts, all signs of desert weathering and soil formation are clearly and everywhere expressed: very weak clay formation, the formation of desert sunburn crusts, widespread calcification of weathering products and soils, salt accumulation with differentiation of geochemical by the elements of the mesorelief.

Tundra zone

The tundra zone is located south of the arctic zone. In Eurasia, it stretches from the northwest of the Kola Peninsula to the Berengov Strait. There are four provinces on the territory of the tundra: Kola, Kaninsko-Pechora, North Siberian and Chukotka-Anadyr.

The North American tundra covers the northern coasts of the continent and the southern part of the North American archipelago.

In the southern hemisphere of the Earth, the tundra zone is not observed.

Climate... The southern border of the tundra approximately coincides with the July air isotherm at 12С. When the average July temperature is below 10-12, trees can no longer grow. Summer, in our understanding, if we call summer days with an average daily air temperature above 12, in the tundra, as a rule, does not happen.

From west to east, the tundra climate becomes more continental - precipitation becomes less, and winters are colder. The Murmansk coast, under the influence of the Gulf Stream, has precipitation of 350-400 mm per year, average temperatures: February -6.2, July-August + 9.1, amplitude - 15.3, while precipitation in the Lena River delta only 100 mm per year, the average temperature in February is -42, and in July + 5, i.e. the amplitude is about 47. Beyond the Kolyma River, the influence of the Pacific Ocean begins to affect, and the climate again becomes more maritime: winters are not so frosty, but summers are cooler.

Frosts are in the tundra from 6 to 8 months, in the delta of the r. Lena even up to 8 1/2 months. However, in winter, Murman is warmer than on the northern coast of the Caspian: January is -6 here, while in Astrakhan -9. In the Siberian continental tundra, frosts reach -50 in January. Winters are colder inland than on the coast. But the summer on the coast is very cool. In summer in the tundra, the weather is unusually changeable: warm days with a positive temperature of 15-20 and warm nights, alternating with rainy and cold days, when at night the temperature drops to -4.

The maximum temperatures in the tundra can be high, but for a short time. For example, in the north of Taimyr, in July, the air temperature is often around 20. In the southern parts of the Subarctic, the air temperature can stay around 25 for several days.

But the level of maximum temperatures is not yet a decisive factor in the development of the organic world of the tundra. The main thing is the duration of the warm period. Certain species of animals, mainly birds and mammals, can be active in the Arctic throughout the year. These are: arctic fox, polar bear, tundra partridge, reindeer. Some can even breed in the winter on the tundra, like lemmings do. But the main part of the tundra community is active only in summer (vegetation, microorganisms, invertebrates). In summer, all the main abiotic processes in the landscape take place: weathering, erosion, thawing of permafrost, etc. Therefore, the duration of the frost-free period, which determines the main features of the tundra landscape, its organic world, is of paramount importance in the life of the tundra.

The total amount of precipitation in the tundra is insignificant, on average 150-250 mm with deviations to the smaller and larger sides. In terms of precipitation, the tundra approaches the desert regions of low latitudes. However, there is a lot of water in the tundra, high humidity of soil and air. Large areas are occupied by swamps. The tundra is more humid than other landscapes of the Earth. Only some areas of boggy taiga regions, for example, in Western Siberia, can compete with it in terms of the abundance of water. Nowhere is the landscape-forming role of water more pronounced than in the tundra. Underground ice, snow, melt water, fogs and prolonged drizzling rains are all powerful ecological and landscape-forming factors in the tundra.

Excess water is associated with low evaporation and transpiration by plants, which generally does not exceed 100 mm per year.

The role of snow in the tundra is diverse: participation in the formation of the thermal regime, in particular, the reflection of solar radiation as a result of high albedo and the absorption of heat for melting; reduction of weathering and denudation processes; protection of plants and animals from winter cold; snow corrosion; limiting the duration of active life, etc. The role of snow is widely known as a heat insulator that protects soil, vegetation and animals from low winter temperatures. In winter, under the snow, conditions are quite favorable not only for the preservation of animals and plants in a dormant state, but also for the active life of warm-blooded animals - lemmings, other voles, shrews, ermine, weasel.

Snow is the most important factor in the winter life of large herbivorous mammals and birds - reindeer, musk ox, white hare, white and tundra partridges. All of them must somehow get to the vegetation hidden under the snow. In the southern half of the tundra zone, the white hare in winter eats bush branches sticking out from under the snow. There are not many hares in the tundra, and this meager and coarse food is enough for them. But there is not enough food for deer and partridge. They cannot dig up a thick layer of very dense snow and migrate to the south in autumn, to the forest-tundra and taiga, where the snow is loose and where there is more food.

The Arctic is a nival landscape, a world of snow and ice. The duration of the snow cover is the main negative factor in the life of most animals and plants. At the same time, snow plays a huge positive role, determines the possibility of the existence of many species, protecting them from the winter cold. Protecting biotopes from the winter cold, snow contributes to the habitation of species of more southern origin in the tundra zone. In areas where there is little snow, life is poorer, but the process of the formation of cold-resistant forms, well adapted to Arctic conditions, is intensifying. All this increases the diversity of the flora and fauna of the North. And this is the guarantee of the prosperity and stability of the tundra communities.

Relief... Most of the tundra is dominated by flat relief, in places hilly, ridged or ridged, abounding in closed thermokarst depressions, occupied by lakes and swamps. In some provinces, the relief is typically mountainous (Khibiny, Polar Urals, Byrranga mountains, Chukotka mountain range, etc.).

Permafrost phenomena - cracking, swelling, solifluction (sliding of soil soils along a slope), thermokarst - form a spotty-small-polygonal and lumpy (mottled-lumpy) microrelief on tundra watersheds and their slopes, large-polygonal and coarse-bumpy slopes. From north to south of the tundra zone, abyssal and thermokarst microforms (hillocks, hillocks) are becoming increasingly important.

Rocks- glacial, marine and alluvial deposits of various texture, often highly stony. In the mountains, the parent rocks are represented mainly by coarse skeletal eluvium of bedrock.

Vegetation... The general landscape-forming features of phytocenoses in the tundra zone can be characterized as follows:

1. A long period of biological permafrost dormancy (about 8 months) and reduced biological activity in summer due to relatively low average daily temperatures and cooling of the soil profile by the cold of permafrost determines the dominance of mosses and lichens, shrubs and shrubs, stunted and sparse perennials. Annuals are practically absent.

2. The vegetation of the tundra develops in conditions of excessive moisture, however, moisture often remains inaccessible to plants, since it is present in the form of ice, therefore, many plants have adaptations to reduce evaporation (just like desert plants): small leaves, pubescence, waxy coating and etc.

3. Low, in comparison with other natural zones of the Earth, the amount of synthesized biomass (4-5 c / ha) and the slow rates of its humification and mineralization. In this regard, the prerequisites are created for the accumulation of semi-decomposed plant residues on the soil surface (peeling). Due to excessive moisture, peat formation and gleying processes are promoted by the dominance of anaerobic processes, both in the organic and in the mineral part of the soil mass.

4. In terms of chemical composition, plant residues are distinguished by extremely low ash content. When they decompose, organic acids are formed, causing strong acidification of the soil mass.

Animal world the tundra is characterized by a poor species composition with a high number of animals. Only a few species endure harsh winter conditions: lemmings, arctic fox, reindeer, ptarmigan, snowy owl, white hare, polar wolf, ermine, long-tailed ground squirrel, weasel, etc. In the tundra of North America, in addition, the musk ox (musk ox ) and caribou - analogue of reindeer. In summer, a lot of migratory birds appear in the tundra, arriving and nesting and attracted by the abundance of various foods (brants, geese, sandpipers, snipe, swans, etc.).

Permafrost... The most important condition for the formation of the nature of the tundra is permafrost. These are layers of soil or ground with negative temperatures throughout the year. The thickness is 1-400 m. Above the permafrost layer there is a layer of earth that freezes in winter and thaws in summer. It is called active layer... Its size ranges from 30-150 cm, depending on the particle size distribution, the presence of a peat layer and geographical latitude. In this limited layer, biological processes take place and soils develop. The wall of the gallery, carved into the permafrost, resembles gray marble with veins and specks in appearance. Sometimes it looks more like a puff cake or a wall made of cast iron. The frozen ground is cemented by ice lenses. This rock ice is tens of thousands of years old. The entire tundra of Russia, Canada and Alaska, except for the Kola Peninsula, is covered by permafrost. Its origin and maintenance is associated with centuries-old subzero temperatures of the surface atmosphere.

Permafrost is one of the factors supporting the swampiness and water content of the tundra landscapes, since it is an aquiclude that prevents vertical filtration of water and drainage of the territory. And, of course, permafrost is a permanent "refrigerator" that reduces the biological activity of soils and weathering crust.

Soil cover... The prevailing tundra soils are of the peat-gley type. The main soil-forming processes are peat formation of organic matter in the upper layers, above the mineral mass, and gleying of the mineral part of the soil profile. Genetic horizons: А т - organogenic peaty, 10-50 cm thick; A - humus, less than 5 cm and G - gley, up to permafrost.

All life in the tundra depends practically on the upper peat horizon.

The gley horizon is abiotic for plants and animals: there is no free oxygen, excess water, acidic reaction of the environment, poisonous compounds of reduced iron and manganese.

The gley horizon, due to oversaturation with moisture, often has thixotropic properties associated with the characteristics of mineral colloids. Thixotropy- the phenomenon of transformation of solid soil mass into liquid (gel into sol). This occurs with mechanical stress on the soil.

Associated with thixotropy solifluction- sliding of the thixotropic soil layer down the slope under the influence of gravity. The gley soil layer liquefies and turns into a quicksand state.

The thixotropy of the gley horizon is associated with the formation spotted tundra... The patches of bare soil (usually 40-50 cm in diameter) are surrounded by a slightly raised ridge of solid moss sod. The ridges of adjacent spots are separated by depressions - hollows filled with peat and loose moss sod. Usually spotted tundras are confined to high terraces. Their formation is associated with the processes of soil cracking, rupture of moss sod, squeezing out of waterlogged soil onto the surface.

Bare soils in spotted tundra are gradually overgrown. In one area, you can find spots that are completely bare and almost completely overgrown with mosses and flowering plants. All this creates a great variety of ecological conditions, due to which the flora and fauna are diverse in the spotted tundra.

With the onset of autumn, hypothermia and freezing of the active soil mass begins from permafrost. The upper horizons are insulated with a moss cover. The increase in pressure during freezing leads to spreading of the thixotropic soil mass of the gley horizon.

In the northern regions of the tundra, it is often found polygonal tundra, which is formed on homogeneous sandy-loamy sediments. Typically polygons are made up of four, five, and hexagons. Convex areas of fine-earth material of the polygonal tundra are often bordered by stony fragments displaced from fine-earth material as a result of cryogenic phenomena. This freezing of stones to the surface of the soil is also associated with the formation of ice under the stone when there is no ice above it. Expanding ice, as a result of long-term cycles, pushes stones to the surface. Freezing of stones on the surface is also due to the fact that the freezing of soils starts from permafrost.

A specific element of tundra landscapes - hillocks-hydrolacoliths... Their height varies from 1 m (2-5 m in diameter) to 70 m (150-200 m in diameter). The appearance of the bumps is explained by the heaving of the soil as a result of the formation of an underground ice lens. Outside, the hillocks are covered with a peat layer about 1 m thick. Beneath it there is a frozen mineral soil consisting of fine-earth deposits, with a thickness of one to several meters. The mineral soil is underlain by a domed mass of ice. Ice lenses are characteristic of permafrost everywhere. Their volume can reach many cubic meters.

Thawing of hydrolacolytes for various reasons, mainly of anthropogenic origin, leads to subsidence of soils and grounds, which are called thermokarst... In this case, failures, shifts, pits are formed, which destroy all ground structures and, first of all, the road network.

In the tundra, there is another type of peculiar landscapes - hilly swamps... On swampy lowlands, flat-topped peat mounds with a diameter of 1 to 10 m and a height of 0.5 to 1.5 m are developed in rows or in groups. They consist of peat formed by mosses growing on their surface. The ridges of hillocks are separated from each other by hollows - swampy waterlogged areas. These bogs are most typical for the subzones of the southern and typical tundras of the western sector of the Subarctic Eurasia. To the north, and especially in the arctic tundra, there are fewer and fewer of them.

Solifluction, formation of spotted and polygonal tundras, hydrolacoliths, thermokarst and some other phenomena are combined under the general name - cryogenesis... This is a set of processes of physical, chemical and biological transformations occurring in soils due to the influence of negative temperatures, i.e. when they freeze, stay in a frozen state and thaw. There are three stages of cryogenesis: 1) the stage of cooling-freezing, which begins when the temperature reaches zero and ends when the entire soil profile or its part capable of freezing is completely frozen in the current year; 2) the frozen stage and 3) the heating-thawing stage, which begins with the penetration of positive temperatures into the soil and ends after the complete thawing of the seasonally freezing layer.

Cryogenesis occurs in all freezing soils. The longer, the deeper the freezing and the lower the temperature, the more tangible the specific effect of cryogenesis, which is most clearly manifested in the tundra.

Tundra zoning... The following four subzones are distinguished in the tundra zone: arctic tundra, typical, or shrub, tundra, southern tundra, and the forest-tundra subzone.

Subzone of the arctic tundra. In the extreme north is the subzone of the Arctic tundra, in which not only trees are absent, but also shrubs, or the latter appear only along the course of rivers. There are absolutely no sphagnum peat bogs in this subzone, the vegetation is sparse and scattered, and there are very few plant species. Areas of spotted and polygonal tundra are widespread. Typical examples of this type are the tundras of northern Yamal, northern Taimyr and southern Novosibirsk islands, Vaigach, Novaya Zemlya, and Wrangel islands. This subzone is located in the area of ​​the present arctic climate. At its southern border, the average July temperatures are 4-5С, at the northern border - about 1.5С. Throughout the summer, temperatures below 0C and snowfalls are possible here. The thickness of the snow cover is insignificant, so the winter conditions for animals and plants are especially harsh.

The main feature of the arctic tundra landscape is the widespread distribution of bare ground. On the watersheds, various variants of communities are developed, in which patches of bare soil are surrounded by plant sod. They are called spotted, medallion, polygonal spotted, etc. Bare soils occupy about 50% of the area. A moss cushion interspersed with twigs of dwarf willows, saxifrage, and cereals is located along a frost crack around the bare ground. Arctic tundras are very diverse: stony, gravelly, clayey with a regular medallion structure, with vegetation in the form of clumps, stripes, nets, etc. Permafrost phenomena in the Arctic tundra subzone are very diverse and noticeable everywhere.

Weakened weathering and intense cryogenic (permafrost) processes create a very diverse, sharply intersected micro- and nanorelief in the Arctic tundra. There are a lot of rock debris and rubble everywhere. The surface of the soil is covered with cracks, depressions, and bumps. At first glance, the bare soils of the Arctic tundra seem lifeless, but a rich world of organisms is developing on them. The upper soil layer is inhabited by a mass of unicellular algae and feeding on them nematodes, enchitreids, collembolans and larger animals - earthworms, larvae of long-legged mosquitoes. On the surface there are many scale lichens that look like mold. Flowering plants are scattered among the rubble - cereals, poppies, siversia, dryad, mytniks, saxifrage, crumbs, forget-me-nots, etc. Neither taiga, nor forest-tundra, nor southern tundra species penetrate into the Arctic tundra. For example, there are absolutely no such species as dwarf birch, crowberry, alpine arctous, lingonberry, blueberry, cloudberry, sedge, ptarmigan, sandpipers - dandy and small bodew, Middendorf vole. Many characteristic mass inhabitants of typical tundra, such as sandpiper-sparrow, dunlin, are few or absent here. All this emphasizes the extreme specificity and originality of the climatic regime of this subzone. To live here, special adaptations are needed to allow them to exist in these harsh conditions.

Subzone of typical tundra. To the south of the arctic tundra, there is a wide subzone of typical, or shrub, tundra, where there are also no trees, but shrubs and, in particular, dwarf shrubs are found not only along river flows, but also on inter-river watersheds. Its boundaries roughly correspond to the July isotherms: 8-11 - in the south and 4-5 - in the north. The area of ​​this subzone is larger than the area of ​​other subzones. In Eurasia, it is well represented in Taimyr, Yamal, Gydan and Yugorsky peninsulas. Between Yana and Kolyma and the rest of it there are only small, mainly southern, fragments. It is completely absent on the mainland west of the Yugorsky Peninsula.

This subzone is the embodiment of the type of landscape that is called tundra. There are no, not only trees, but also quite tall shrubs on the watersheds. The height of the vegetation is completely determined by the thickness of the snow cover. Due to snow corrosion, only those plants that are hidden under the snow can survive the winter. Meanwhile, its thickness is small, most often 20-40 cm. Shrub thickets up to 1 m high are developed in lowlands, in stream valleys and along the shores of lakes, where a lot of snow accumulates.

Typical tundras are the kingdom of mosses. A powerful moss cushion covering the soil with a continuous layer, usually 5-7 cm thick, in places up to 12 cm thick. The moss cover plays a huge and controversial role in the life of the tundra. It is mosses that provide complete closeness of vegetation in watersheds. They have a great influence on soil temperature and the dynamics of seasonal soil thawing. On the one hand, the moss cover delays the thawing of permafrost, prevents the heating of the soil and, thus, has a negative effect on the development of organisms. The thicker and denser it is, the colder the soil and the higher the permafrost level. On the other hand, the moss cover prevents the formation of thermokarst and thus has a stabilizing effect on the vegetation. The detrimental effects of peeling off moss turf as a result of, for example, tracked vehicles, are well known.

Moss turf is home to a rich complex of invertebrates called hemiedaphon (semi-soil). It includes a large number of species of springtails, ticks, spiders, insects. At the same time, typical soil forms also live in the moss layer, for example, earthworms, enchitreids, larvae of long-legged mosquitoes, ground beetles, etc. The life of lemmings depends on mosses. They lay complex labyrinths of passages in the sod, in winter they feed on the fleshy parts of flowering plants hidden in its thickness.

The herbaceous layer is mainly composed of various sedges. There are arctic bluegrass, polar poppy, etc. There are many creeping shrubs (polar willows, dwarf birch, partridge grass, cassiopeia, lingonberry, crowberry, etc.). Sometimes cotton grass and dicotyledonous herbaceous plants (saxifrage, wintergreens, asteraceae, etc.) are abundant. In some places in the moss sod there are many lichens (leafy, tubular, bushy, scale, etc.).

In addition to the main communities with a continuous moss cover, spotted tundras are also very common in the subzone.

Southern tundra subzone... To the south of the typical tundra in the form of a narrow strip, the subzone of the southern tundra stretches. There are already trees in this subzone, but the forest areas formed by them are located only along the rivers. On the watersheds, there are only shrub thickets, at most single trees. Sphagnum peat bogs are well developed and already abundant.

The shrub layer is developed in the main areas of the watersheds. It is formed by birches, willows, alder trees. Herbaceous plants (sedges, cotton grass, cereals) and shrubs (blueberries, lingonberries, wild rosemary) are abundant under the canopy of shrubs. Below there is a continuous moss cover.

In the southern tundra, single woody plants are found, most often larch. They are short, have curved thin trunks or a special, elfin-like shape.

The vegetation cover is very diverse in the southern tundra. The watersheds are interspersed with thickets of willows, birches (dwarfs), alder and tundra without shrubs with a continuous moss cover or with spots of bare ground. In the depressions, various bogs are developed - hypnum, sphagnum, flat and peat mounds. On the southern slopes there is a vegetation cover of cereals, legumes, and various forbs. On the raised edges, there are thickets of berry bushes and semi-shrubs: lingonberries, blueberries, crowberries, arctous, etc. Near water, near lakes and along the banks of streams, various near-water plant groups of sedges, horsetails, and grasses are developed.

The main manifestation of the severity of the polar climate in this subzone is the absence of arboreal vegetation here. Otherwise, the southern tundra is a relatively wealthy community. The flora and fauna are very diverse here. In addition to typical tundra species, there are many inhabitants of middle latitudes. For example, in the European and Siberian southern tundra plants everywhere you can find the common ones in the middle lane - marsh cinquefoil, common spleen, marsh marigold and even heat-loving common thyme; from birds - warbler, thrush, common snipe and short-eared owl. Pintail nests here on the lakes, and the widespread root vole lives along with typical tundra rodents.

Subzone of the forest-tundra. On the southern edge of the tundra zone, on the border of it with the area of ​​continuous forests, there is a transitional subzone of the forest-tundra, where forests and woody vegetation are distributed not only along river flows, but, in the form of islands, also rise to the interfluvial watersheds. Sphagnum peat bogs reach enormous development here and form a special type of hilly tundra.

Forest-tundra - a zone of small forest of dwarf birch, small willow, juniper with individual undersized spruce and larch trees. The harsh conditions of the tundra, the lack of nutrients, and the presence of permafrost at a shallow depth impede the growth and development of woody plants. Trees 200-300 years old are undersized, clumsy, knotty, have a diameter of 5-8 cm.

In the southern tundra, you can find larch, which looks like a highly branched bush pressed to the ground, rising only 30-50 cm. This is the so-called elfin form, which is formed by many tree species in the Subarctic. Sometimes they form dense, difficult-to-pass thickets. Dumplings are especially characteristic of mountainous regions and the Far Eastern North, where the tundra landscape descends to very low latitudes and covers the areas of many tree species. So everywhere the cedar elfin is widespread, which is considered either a kind of cedar pine or a special species. In the thickets of dwarf trees, favorable conditions are created for wintering animals: under the snow lying on top of thick bushes, there are many voids, in some places the surface of the litter or soil is open. This makes it easier to move around and get food.

Some features of the animal world. Among the animals found on the territory of the Subarctic there are a lot of predatory animals: wolf, fox, wolverine, brown bear, weasel, ermine, several species of shrews. This is a characteristic feature of the tundra mammalian fauna. However, all of these species are aliens from other zones. Among carnivorous mammals, there are only two representatives of the truly arctic fauna - the arctic fox and the polar bear. Arctic fox is the only primordially tundra species of predatory animals of significant importance in the biocenoses of the Arctic. But among herbivorous rodents and ungulates, the largest number of characteristic tundra endemics is found. These are hoofed and Ob lemmings, musk ox and reindeer, narrow-headed vole and Middendorf's vole.

The most impressive are wild deer. Wild deer have survived mainly in the form of three herds: on the Kola Peninsula in a protected regime, in Taimyr and in the north of Yakutia. The territory occupied by these herds is small in relation to the total area of ​​the reindeer husbandry zone.

The largest herd is Taimyr. The places of its main summer migrations and calving are where grazing by domesticated ones is clearly unprofitable. Only the wild form is able to successfully use the vast unproductive pastures of these harsh high-latitude landscapes without causing significant disturbances to the vegetation cover. The mountainous areas of Putorana, where wild deer concentrate for wintering, are also not very suitable for use by reindeer herding farms. Contact between wild and domestic deer in these areas is possible only for relatively short periods. The Taimyr herd, numbering 400 thousand heads, is our national pride. The world's only nesting of white geese on Wrangel Island is also a national pride.

In the tundra, there are huge flocks of migratory birds that fly to nest in the summer: tundra and American swans, partridges, red-breasted goose, snowy owl, loons, sandpipers, etc.

Agricultural use of the tundra... Farming on a large scale in the tundra zone is impossible. Only small consumer gardening is widespread in it, they sow turnips, radishes, onions and plant potatoes.

The main occupation in the tundra is reindeer husbandry, based on scarce forage reserves. The main winter pasture for reindeer is lichens - moss, which in the form of lichen tundras, although occupying a fairly large area, grow extremely slowly, and, in particular, poorly renew after grazing and trampling. The increment for different subzones is: in the forest-tundra - 4-6 mm over the summer, in a typical tundra - 2-3 mm, and in the arctic - 1-2 mm.

It goes without saying that after their destruction by grazing, lichens on pastures are renewed extremely slowly. In different regions, the renewal period, almost equal to the pasture turnover, is determined on average 15-30 years. A heavily grazed reindeer pasture should not be revisited until after 15 years.

Yagel and other lichens make up the dominant, almost 9 months of the year, but not the exclusive food for deer. In the summer, when the snow melts in the tundra, the reindeer need other food and other types of so-called summer pastures. At this time, they need shrub tundra and river valleys with their trees and shrubs. Since the deer is predominantly a tree-eating animal, and not a herbivore, in the presence of shrubs and grasses, it always prefers the former. It feeds at this time, mainly, branches, leaves and young shoots of dwarf birch or polar birch and willow trees, to a lesser extent herbaceous plants: sedges, cotton grass and cereals.

The protein regime of reindeer food is also peculiar. Since lichens are poor in nitrogenous substances, feeding the animal with them for 8-9 months causes all the signs of protein and mineral starvation in it. To cover the lack of protein during the summer, deer are extremely willing to eat various mushrooms, often appearing in many in drier areas of the tundra. Throughout autumn, and sometimes the beginning of winter, digging up dried mushrooms from under the snow, the deer are busy looking for mushrooms and the failure of such crops causes a lot of trouble for the reindeer breeders.

Thus, reindeer husbandry is naturally a nomadic economy, for in winter it needs lichen pastures, in spring wet low-lying swamps and river valleys, and in autumn dry moss-lichen or moss tundras.

This ecoregion covers the north of the mainland of North America. Of course, it has much in common with the Eurasian tundra: many species of fauna inhabiting the North American territories are either relatives of the Eurasian species, or are distributed in general on both continents. The problems facing the defenders of the tundra are also very similar: the development of oil and gas fields leads to catastrophic pollution of the unique natural world.

The Arctic tundra is an area of ​​low, flat and swampy coastal plains covered with lakes filled with melted ice.

LINK IN A TUNDRA CHAIN

The tundra of North America is part of the natural tundra zone of the Northern Hemisphere.

The American tundra zone occupies the northern part of the North American mainland and runs from northern Alaska along the coast of Good Zone to the north of Labrador and Newfoundland. In the east, where the influence of the Labrador Current affects, the tundra extends to 55-54 ° N. sh.

To the north of the distribution border of broad-leaved and coniferous trees, there are shrub tundras, where unpretentious plants such as creeping heather, dwarf and polar birch, willow, alder and low shrubs prevail.

Since the tundra of North America is located in areas where the waters of the Arctic Ocean go deep into the land, there is a very confusing picture of the wind regime, with frequent changes in direction and different strengths. Therefore, the geography of distribution of tundra plants is extremely complex. Since this area is in many ways similar to the forest-tundra and taiga, it is not surprising that, all of a sudden, for a traveler, low and bent in all directions vegetation in open places is suddenly replaced by tall trees in river valleys and at the foot of the mountains.

However, when moving northward, the predominance of real tundra with mosses, lichen, sedge and cotton grass becomes more and more noticeable, and tree tracts disappear completely.

The peculiarity of the North American tundra is the wide distribution of the arctic landscape - low, flat and swampy coastal plains. The vegetation here is sparse, with a short vegetative period and is represented mainly by mosses and lichens. It does not form an even cover and often sows cracks in the soil formed due to severe frosts. Where ice and earth are mixed, ice wedges and mounds of frost are formed, nicknamed pingo in Sulfur America.

The climate of the North American tundra is very harsh. The wind here is gaining extreme strength, it blows snow into the lowlands, where snow drifts are formed, which persist even in summer. It is because of the lack of snow on the plains that the soil freezes over and does not have time to warm up in a short summer. Over a large area, the climate of the Arctic tundra is more humid and damp than within the boundaries of the circumpolar tundra, which extends from American Alaska eastward to Canadian Quebec.

Separately, the tundra of the northwest of North America is distinguished - the Alaska Range and the St. Elijah Mountains. This ecoregion includes the mountains of the interior of Alaska, permanently covered with ice and snow. Those rare areas that remain ice-free are rocky, rocky and alpine tundra.

The occupations of the local population in the tundra of both North America and Eurasia are similar. These are reindeer husbandry (the arctic tundra becomes extensive reindeer pastures in the summer), hunting for sea animals (according to the quotas of the Ministry of Natural Resources) and fishing. Among the crafts - bone carving and sewing clothes and shoes from reindeer skins. There are no large cities in the tundra of North America.

The tundra zone occupies the northern coast of North America. The southern border of the tundra in the west runs at the Arctic Circle, and in the east it deepens into more southern latitudes, capturing the coast
Hudson Bay and the northern part of the Labrador Peninsula.

TUNDRA UNDER THE THREAT

The biggest threat to the North American tundra comes from oil and gas pipelines, hydrocarbon exploitation and global warming.

The fauna of the North American tundra is much richer in species composition than vegetation. Of large mammals, the prevailing caribou deer, brown bear, polar wolf, polar weasel, polar bear and musk ox (musk ox), small mammals - fox, arctic fox, lemming and ermine, birds - white goose, black goose, white and tundra partridge , Alaskan plantain (a bird of the bunting family) and the white owl, from marine mammals - seal, walrus, narwhal, beluga whale, bowhead whale. There are a lot of fish in the rivers: lake trout, whitefish, grayling.

However, only a very small part of the flora and fauna of the North American tundra is characteristic only of these places. It took the specialists a long time to find out. For example, at the dawn of the study of animals in North America, the caribou deer and the Eurasian reindeer were considered different species (today in America there are two subspecies of caribou - tundra and forest), and together with them - the American and Eurasian elk. Later studies of the movement of species along the Bering Isthmus, which once connected North America and Eurasia, showed that all these species are related or even identical.

There are many examples of this. The gray-haired marmot is a typical inhabitant of the mountain American tundra - the brother of the mountain-tundra Siberian black-capped marmot. The long-tailed gopher, an inhabitant of the American tundra, also lives in Siberia. The musk ox could be called a "Native American" if you do not know that it disappeared from the tundra of Eurasia during the time of primitive people who mercilessly destroyed the animal population.

In general, most of the American tundra endemics are represented by relatively young species that have recently separated from their closest relatives of the same genus.

A completely unique phenomenon for the tundra of North America is the distribution of certain species of birds that arrive here only in the summer months: among such species arriving on the Labrador Peninsula, even several species of tropical hummingbirds, junco (a genus of passerine birds from the bunting family, characteristic only for North America ), bush bunting (only rarely found in the tundra of Chukotka), Canadian goose (the most widespread species of game here).

The farther north, the poorer the fauna and the more its life is connected with the sea: these are auks and gulls nesting on the rocks, and pinnipeds with polar bears. A rare visitor from the depths of the southern tundra is the Arctic fox and snow bunting.

The problems associated with the pollution of the tundra are largely similar for different parts of it due to the nature of the minerals being developed here, their storage and transportation. Despite the strictest control and multimillion-dollar fines for leaks from oil pipelines, environmental pollution continues, deer refuse to use special passages, and road trains rip off the upper protective layer of tundra soils with caterpillars, which takes almost a hundred years to restore.

FUN FACTS

■ The Mackenzie River was discovered and first crossed by the Scottish explorer Alexander Mackenzie in 1789. Its original name is Disappointment, which literally means “disappointment” in English. By assigning such a strange name to the river, Mackenzie expressed his own frustration at the fact that she had taken him not to the Pacific Ocean, but to the Arctic.

■ The term "pingo" as a typical North American designation for a mound of heaving first appeared in 1938. It was borrowed from the Eskimos by the Danish-Canadian botanist Alf Porslig.

■ The easiest way to get into the interior of the North American tundra is to take the highway along the Trans-Alaska Pipeline, which runs from Barlowdo to the Pacific port of Valdez and poses the greatest threat to the ecology of the North American tundra.

■ Tundra plant Labrador tea has red leaves to use chlorophyll and heat from the sun to keep warm. None of the tundra animals eat it.

■ The North American tundra receives less rainfall annually than the Mojave Desert.

ATTRACTION

■ Natural: Gates of the Arctic National Park and Preserve (Alaska, USA), Kobuk Valley National Park (Alaska, USA), Wapusk and Yukkusaiksalik National Parks (Hudson Bay Coast, Canada), Gross National Park Morne (Newfoundland Island, Canada), Thorngat Mountains National Park (Labrador Peninsula, Canada).

Atlas. The whole world is in your hands №255

Spotted tundras are widespread in the Arctic and are found in the alpine belt of some mountain uplifts. There is no doubt that they are not the same in nature and have different origins. Several hypotheses are known that explain in one way or another the genesis of bare spots in these tundras.

According to V.N.Sukachev, the formation of spots in the Arctic tundra is a consequence of the freezing of the soil in the presence of permanent (permafrost) permafrost. Excessively moistened loam before freezing is a semi-liquid mass - "quicksand". This semi-liquid layer expands upon freezing and breaks through the frozen surface crust in weak places (along cracks, etc.), pouring out like a small mud volcano. So, as a result of the outpouring of quicksand on the surface, compressed from below by constant and from above by seasonal permafrost, naked exposed spots devoid of vegetation are formed. Then, undergoing erosion, they expand and deepen.

L. N. Tyulina develops V. N. Sukachev's hypothesis in relation to the mountain tundra of the Southern Urals (Mount Iremel). In her opinion, spots in the mountain tundra appear as a result of the outpouring of a mud volcano on the surface, tearing the plant sod. Then the spots, undergoing erosion, increase in size. The erosion of the plant sod is also favored by the bulging out of the soil of stone blocks during freezing. LN Tyulina attaches great importance to permafrost in the formation of characteristic elements of the relief and microrelief on Mount Iremel, although she did not manage to get to the frozen horizon and no evidence was given in favor of its existence.

In the highlands of the extrapolar part of the Urals, no one has yet observed permafrost in mineral soils. Nevertheless, this fact does not bother some researchers, who assume its presence in the high-mountainous region of the Ural ridge. Not to mention the articles by L.N. Tyulina, the later published work of N.A. ... From the work of N.A. Preobrazhensky, it can be concluded that its author actually did not have any data on this issue and refers only to rare cases of the presence of small snow patches on some loaches of the Southern Urals, which in some years do not have time to completely melt over the summer. Even the findings of sporadic permafrost in the foothills of the Northern Urals do not yet prove its presence in the highlands of the Southern Urals.

According to BN Gorodkov, “dry spotty tundra arises under the influence of winter winds blowing snow from open places and blowing frozen vegetation into fine earth, which is also subject to snow corrosion. From frost and drying, the soil surface cracks into polygonal detachments, the vegetation cover is preserved only along cracks and grooves between weakly convex ones, due to the crumbling of the edges, with bare spots. In spring and during rain, the spots are saturated with water, puddles sometimes stagnate on them, loam swells and becomes semi-liquid, which is why on weak slopes the surface of the spots takes a horizontal position. " In addition to "dry", BN Gorodkov distinguish "wet" spotty tundra, in which spots appear as a result of the removal of fine earth to the surface by oozing subsoil streams. In this case, the loam often slips, tearing the turf and exposing the soil. The formation of bare spots, according to BN Gorodkov, may be a consequence of other reasons: erosion by rains and spring waters, soaking, damage by deer hooves.

LN Tyulina and BN Gorodkov proceed from the fact that spots in mountain tundra are formed as a result of destruction or rupture of the sod of the vegetation cover that binds the soil surface. In contrast, V.S.Govorukhin believes that spots appear before vegetation. In the upper reaches of the Khulga and Synya rivers, high in the mountains, he discovered areas of "anorganic spotted tundra" with characteristic stepped areas of fine earth, but completely devoid, in the opinion of this researcher, of any vegetation. Having traced in nature a number of links in the chain of gradual overgrowing of such areas, V.S.Govorukhin came to the conclusion that a stepped microrelief, characteristic of spotted tundra, is initially formed in the highlands. In winter, under the influence of severe frosts, the surface is divided into polygons. The viscous semi-liquid masses of the formed detachments gradually slide down the slopes. In this case, the heaviest particles slide lower, while the finer ones settle higher. Then vegetation appears on the margins of the bare spots and in the hollows between them. According to this researcher, the spotted tundras observed in the high mountains of the Urals characterize different stages of the advance of vegetation on the lifeless territories that were freed from the ice cover in the past. The term “anorganic tundra” proposed by V. S. Govorukhin cannot be considered a success. The concept of "tundra", along with special environmental conditions, includes a certain complex of plants, and a tundra without plants is as difficult to imagine as a forest without trees. Therefore, if such completely lifeless ("anorganic") territories in the high mountains of the Urals really existed, they could not be called tundra. However, even relatively recently (in the geological sense), the exposed rocky substrate seems lifeless only at first glance. In fact, it is inhabited by microorganisms, scale lichens, and often also by mosses, that is, it is not "anorganic".

VB Sochava, who studied the spotted tundras of the Anadyr region, believes that the formation of spots is the result of partial degradation of the peat layer in those areas where further peat growth has ceased. This causes uneven freezing of the active soil layer (in degraded areas the soil freezes earlier), the appearance of vertical stresses in the degrading peat layer, the protrusion of the mineral soil upward and the formation of bare spots. Subsequently, the process of peat formation begins again on bare spots.

Comparing the available literature data, it is easy to see that spotted tundras are very diverse in their structure and origin. The spotted tundras of the high-mountainous region of the Urals differ sharply from the Anadyr spotted tundras described by VB Sochava. But even within the limits of the Ural ridge, the mountainous spotted tundras are not the same, they fall into several types, which have different origins.

As for the spotted mountain tundras described by us, the formation of clay-gravelly spots in them is associated mainly with the rupture of plant sod by semi-liquid quicksand, which lies on a stony substrate. At the moment of freezing of the upper soil horizon, quicksand, experiencing pressure from both sides, breaks through the plant sod. The resulting bare areas are subsequently washed away by rain and melt waters. Then they expand and are connected by tubules, through which the excess of liquefied clay flows down. Further erosion of bare spots leads to the fact that small clay particles are gradually carried away by water into the depths, and the clay surface of the spot decreases more and more, and the outer edge of the sod is washed out in width. Thus, in the mountain tundra, rounded pits (cauldrons) with a rocky bottom are formed. The cracks under the stones serve as the initial ways of washing the fine earth from the surface of the spots into the depth of the placer. The washed-in fine-earth material is carried out by spring waters into streams flowing out from under the placers.

Thus, sunspot formation in the mountain tundra of the Urals is most correctly explained by the hypothesis of V.N.Sukachev, originally proposed for the flat arctic tundra, and then developed and supplemented in relation to the natural conditions of the mountain peaks of the Urals. Taking a number of the provisions of L.N. Tyulina, we do not consider it necessary to use the hypothetical factor of permafrost to explain the causes of spot formation in the mountain tundra of the Urals, especially in its southern part. The fine-earth soil layer on the Urals charr is underlain by boulders and gravel, therefore, when the surface layer of the soil freezes, it is quite possible that quicksand will pour out onto the surface.

The most distinctly late stages of spot formation (the emergence of cauldrons with a rocky bottom) are traced in the Southern Urals (especially on Mount Iremel). The process of spot formation in the mountain tundra went further here, which is probably due to the fact that the loaches of the Southern Urals were freed from glaciation earlier.

Spot formation in the mountain tundra of the Subpolar and Northern Urals is significantly enhanced as a result of excessive grazing by deer, which damage the plant sod with their hooves.

Consequently, spotted tundras do not represent an independent stage in the development of mountain tundra vegetation. The formation of bare spots occurs in moss-dwarf shrubs, moss-shrubs, and grass-moss tundra, i.e., in those types of tundra where the fine earth layer is more developed.

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Arctic deserts (polar desert, ice desert), a type of desert with extremely sparse sparse vegetation among the snows and glaciers of the Arctic and Antarctic belts of the Earth. Distributed in most of Greenland and the Canadian Arctic Archipelago, as well as on other islands of the Arctic Ocean, on the northern coast of Eurasia and on islands near Antarctica.

The Arctic desert is home to small isolated areas with mainly crustaceans and lichens and herbaceous vegetation. They look like a kind of oases among polar snows and glaciers. In the conditions of the Arctic desert, there are some types of flowering plants: polar poppy, foxtail, buttercup, saxifrage, etc.

The Arctic Desert Zone occupies the northernmost edge of Asia and North America and the Arctic Basin Islands within the polar geographic zone. The climate of the zone is arctic, cold, with long severe winters and short cold summers. The seasons are conditional - winter is associated with the polar night, summer is associated with the polar day. Average temperatures in the winter months range from -10 to -35 °, and in northern Greenland to -50 °. In summer, they rise to 0 °, + 5 °. Little precipitation falls (200-300 mm per year). This zone is also called the kingdom of eternal snows and glaciers. In a short summer, only small areas of land with stony and swampy soils are freed from snow. They grow mosses and lichens, occasionally flower plants.

The ice zone (zone of arctic deserts) - the northernmost in our country - is located in the high latitudes of the Arctic. Its extreme south lies at about 71 ° N. sh. (Wrangel Island), and north - at 81 ° 45 "N (Franz Josef Land Islands). The zone includes Franz Josef Land, the northern island of Novaya Zemlya, Severnaya Zemlya, Novosibirsk Islands, Wrangel Island, the northern outskirts Of the Taimyr Peninsula and the Arctic seas located between these land areas.

The high latitude determines the exceptional severity of the nature of the ice zone. Its landscape feature is ice and snow cover, which lies almost throughout the year. Positive average monthly air temperatures, close to zero, are observed only in the lowlands, and, moreover, no more than two to three months a year. In August, the warmest month, the average air temperature does not rise above 4–5 ° in the south of the zone. The annual amount of precipitation is 200-400 mm. The overwhelming majority of them fall in the form of snow, frost and frost. Snow cover even in the south of the zone is about nine months a year. Its thickness is relatively low - on average no more than 40-50 cm. Large clouds, frequent fogs and strong winds aggravate the unfavorable features of the ice zone climate.

The relief of most of the islands is complex. Flat, low-lying plains, where the zonal landscape is best expressed, are characteristic of coastal areas. The interior regions of the islands are usually occupied by high mountains and mesas. The maximum absolute marks on Franz Josef Land reach 620-670 m, on the northern island of Novaya Zemlya and on Severnaya Zemlya they are close to 1000 m. The exception is the New Siberian Islands, which have a flat relief everywhere. Due to the low position of the snow boundary, significant areas on Franz Josef Land, Novaya Zemlya, Severnaya Zemlya and the De Long Islands are occupied by glaciers. They cover 85.1% of Franz Josef Land, 47.6% of Severnaya Zemlya, 29.6% of Novaya Zemlya.

The total area of ​​glaciation on the islands of the Soviet Arctic is 55 865 km 2 - more than 3/4 of the area of ​​the entire modern glaciation of the territory of the USSR. The firn feeding zone in the southeast of Franz Josef Land begins at an altitude of 370-390 m; somewhat lower - from 300-320 to 370-390 m - lies the feeding zone of "superimposed" ice on Novaya Zemlya - above 650 - 680 m, on Severnaya Zemlya - at an altitude of 450 m. The average thickness of the ice sheet on Novaya Zemlya is 280-300 m, on Severnaya Zemlya - 200 m, on Franz Josef Land - 100 m. In places, continental ice descends to the coast and, breaking off, form icebergs. The entire land area, free from ice, is bound by permafrost. Its maximum thickness in the north of the Taimyr Peninsula is more than 500 m. There are fossil ices of veined and partly glacial (on Novaya Zemlya) origin.

The seas of the Arctic Ocean, washing islands and archipelagos, represent a special, but integral part of the landscape of the ice zone. For most of the year, they are completely covered with ice - a long-term Arctic pack, passing into the coastal fast ice in the south. At the junction of the pack and fast ice, in areas with a predominant ice removal, stationary openings are formed tens and even hundreds of kilometers wide. Distinguish between the Canadian and Atlantic Ocean ice massifs with a division zone in the area of ​​the Lomonosov ridge. The younger and less powerful ice of the Canadian massif is characterized by an anticyclonic circulation system (clockwise), the ice of the Atlantic massif - an open cyclonic system (counterclockwise), in which they are partially carried out into the Atlantic Ocean with the help of the East Greenland Current. VN Kupetsky (1961) suggests distinguishing here the landscapes of drifting ice in the Central Arctic and the low-latitude Arctic, fast ice, ice on the continental slope, and stationary ice-floes. The last two types of landscapes are characterized by the presence of open water among the ice and a relatively rich organic life - an abundance of phytoplankton, birds, the presence of polar bears, seals, and walrus.

Low air temperatures promote vigorous development in the ice zone of frosty weathering, sharply slowing down the intensity of the processes of chemical and biological weathering. In this regard, the grounds and soils here consist of rather large fragments of rocks and are almost devoid of clay material. The frequent transition of air temperature through 0 ° in summer with the close occurrence of permafrost causes an active manifestation of solifluction and heaving of soils. These processes, combined with the formation of frost cracks, entail the formation of so-called polygonal soils, the surface of which is dissected by cracks or rolls of stones into regular polygons.

Water erosion processes in the zone are greatly weakened due to the shortness of the warm period. Nevertheless, here, too, under favorable conditions for these processes (steep slopes) and the presence of loose rocks, a dense ravine network can develop. Gully landscapes are described, for example, for the north of Novaya Zemlya, the Novosibirsk Islands, the Vize and Isachenko Islands, and the Taimyr Peninsula. The development of ravines on the New Siberian Islands is facilitated by thick layers of buried ice. Buried ice, opened by frost cracks or erosional erosion, begins to vigorously melt and the melt water intensifies the erosion process.

The thawing of permafrost and the horizons of buried, injection and polygonal-veined ice enclosed in it is accompanied by the formation of gaps, depressions and lakes. This is how a kind of thermokarst landscapes, characteristic of the southern regions of the zone, and especially for the New Siberian Islands, arise. In the rest of the greater part of the ice zone, thermokarst landscapes are rare, which is explained by the weak development of fossil ice here. Thermokarst depressions are common here only on ancient moraines, under which ice of retreating glaciers is buried. Thermokarst and erosional erosion of loose sediments is associated with the formation of cone-shaped earthen hillocks-baidzharakhs with a height of 2-3 to 10-12 m. Small-hilly baidzharakh landscapes are characteristic of the sea and lake coasts of Taimyr and the New Siberian Islands.

By the nature of the vegetation, the ice zone is an Arctic desert, characterized by torn vegetation cover with a total coverage of about 65%. On the inner plateaus, snowless in winter, mountain peaks and moraine slopes, the total cover does not exceed 1-3%. Mosses, lichens (mainly scale), algae and a few species of typical arctic flowering plants prevail - alpine foxtail (Alopecurus alpinus), arctic pike (Deschampsia arctica), buttercup (Ranunculus sulphureus), snow saxifrage (Saxaverraga nivalare ). The entire island flora of higher plants here numbers about 350 species.

Despite the poverty and monotony of the vegetation of the Arctic deserts, its character changes as it moves from north to south. In the north of Franz Josef Land, Severnaya Zemlya, north of Taimyr, grass-moss arctic deserts are developed. To the south (south of Franz Josef Land, northern island of Novaya Zemlya, Novosibirsk Islands), they are replaced by depleted shrub-moss arctic deserts, in the vegetation cover of which shrubs, pressed to the ground, are occasionally found: polar willow (Salix polaris) and saxifraga (Saxifraga oppo-sitifotia) ... The south of the ice zone is characterized by shrub-moss arctic deserts with a relatively well-developed shrub layer of polar willow, arctic willow (S. arctica) and dryad (Dryas punctata).

Low temperatures in summer, sparse vegetation and widespread permafrost create unfavorable conditions for the development of the soil-forming process. The thickness of the seasonally thawed layer averages about 40 cm. Soils begin to thaw only at the end of June, and at the beginning of September they freeze again. Waterlogged at the time of thawing, in summer they dry out well and crack. In vast areas, instead of formed soils, placers of coarse detrital material are observed. On lowlands with fine-earth soils, arctic soils are formed, very thin, without signs of gleying. Arctic soils have a brown profile color, a slightly acidic, almost neutral reaction, an absorbing complex saturated with bases. Their characteristic feature is their iron content, caused by the accumulation of low-mobile iron-organic compounds in the upper horizons of the soil. Arctic soils are characterized by complexity associated with microrelief, soil and vegetation composition. According to IS Mikhailov, “the main specific feature of the Arctic soils is that they are like a“ complex ”of soils with a normally developed profile under plant sod and with a reduced profile under algal soil films.

The productivity of the vegetation cover of the Arctic deserts is negligible. The total stock of phytomass is less than 5 t / ha. Characterized by a sharp predominance of the living aboveground mass over the underground, which distinguishes the arctic deserts from the tundra and deserts of the temperate and subtropical zones, where the ratio of aboveground phytomass to underground is the opposite. Low productivity of vegetation is the most important reason for the poverty of the fauna of the ice zone.

The natural tundra zone is located in the northern hemisphere on the northern coast of Eurasia, North America and some islands of the subpolar geographic belt, occupying about 5% of the land. The climate of the zone is subarctic, characterized by the absence of climatic summer. Summer, which lasts only a few weeks, is cool, with average monthly temperatures not exceeding + 10 - + 15 ° С. Precipitation occurs often, but their total amount is small - 200 - 300 mm per year, most of which falls on the summer period. Due to low temperatures, the amount of accumulated moisture exceeds evaporation, which leads to the formation of vast wetlands.

The winter is long and cold. During this period, the thermometer can drop to -50 ° C. Cold winds blow throughout the year: in summer from the Arctic Ocean, in summer from the mainland. Permafrost is a characteristic feature of the tundra. The poor flora and fauna are adapted to the harsh conditions of existence. The tundra gley soils of the zone contain a small amount of humus and are oversaturated with moisture.

The Arctic tundra is a vegetation-poor area located between the North Pole and the coniferous forests of the taiga. In winter, all the water here freezes, and the area turns into a snow-covered desert. Under the snow is a layer of frozen soil about 1.5 km thick, which warms up by 40-60 cm in summer. The polar night lasts for months. Strong winds are blowing, the ground is cracking from frost. In the tundra of Greenland, wind speeds can reach 100 km / h. Even in summer, the local landscape does not please the eye with its variety. Placers of rubble and bare loam are everywhere. Only here and there are spots and stripes of greenery visible. Therefore, these places are called spotted tundra.

Where the summer is longer, where the ground warms up deeper, and in winter there is more snow, the moss-lichen (typical) tundra stretches in a wide strip. The flora is richer and more diverse here. In summer, rivers and lakes sparkle in the sun, playing with the waters, surrounded by bright blooming vegetation. In the middle of summer, the Polar Day begins, which lasts for several months. Typical tundra is dominated by herbaceous plants, represented by sedge, marsh mytnik, cotton grass. In river valleys and on slopes sheltered from the wind, dwarf birch, alder, polar willow, and juniper grow. They are very low and do not rise above 30 - 50 cm. Low growth contributes to the maximum use of the heat of the upper layers of the soil in summer and better protection of the snow cover from wind and frost in winter. The thickness of the snow is measured by the height of the shrub in the tundra.

Most of the tundra is used as a summer pasture for deer. The yagel, which deer feed on, grows very slowly, only 3 - 5 mm per year, so the same pasture cannot be used for several years in a row. It takes 10-15 years to restore the lichen cover.

Difficult climatic conditions, constant struggle for survival are not the only problems of the modern tundra. The construction of oil pipelines that pollute the soil and water bodies, the use of heavy equipment that destroys the already poor vegetation cover leads to a reduction in pasture areas, the death of animals and puts this region on the brink of an ecological catastrophe.

Tundra zones, natural zones of continents, mainly of the Northern Hemisphere (in the Southern Hemisphere they are found in small areas on islands near Antarctica), in the Arctic and subarctic belts. In the Northern Hemisphere, the tundra zone is located between the arctic desert zones in the North, and the forest-tundra in the South. It stretches in a strip 300-500 km wide along the northern coasts of Eurasia and North America.

Distinctive features of the Tundra zone are treelessness, the predominance of a sparse moss-lichen cover, strong swampiness, widespread permafrost and a short growing season. The harsh climatic conditions of the Tundra zone determine the impoverishment of the organic world. The vegetation includes only 200-300 species of flowering plants, about 800 species of mosses and lichens.

Plants of the tundra.

1. Blueberries.

2. Lingonberry.

3. Black crow.

4. Cloudberry.

5. Loydia is late.

6. Skoroda onion.

7. The prince.

8. Vaginal fluff.

9. Mechelistnaya sedge

10. Dwarf birch.

Most of the tundra zone of the Northern Hemisphere is occupied by Subarctic Tundras (northern and southern), on its northern outskirts giving way to Arctic Tundras, where there are no thickets of bushes, along with mosses, lichens and grasses, arctoalpine shrubs play an important role.

In the East European part of Russia and in Western Siberia, the southern Tundras are characterized by large-birch Tundras, with a well-defined layer of dwarf birch with an admixture of willows. Towards the North, the layer of shrubs is thinning, they become more squat and a large role in the vegetation cover, along with mosses, dwarf shrubs and semi-creeping shrubs, sedge, there is an admixture of dryads. In Eastern Siberia, with the increasing continentality of the climate, large-birch tundras are replaced by small-birch tundras with another species of birch. In Chukotka and Alaska, tussock Tundras dominate with cotton grass and sedge, with the participation of hypnum and sphagnum mosses and an admixture of low-growing shrubs, which are decreasing towards the North. The subarctic Tundras of Canada and Greenland are dominated by Tundras dominated by ericoid shrubs. Tundras serve as pastures for deer, hunting grounds, and places for picking berries (cloudberries, blueberries, shiksha).

The tundra of North America is part of the natural tundra zone of the Northern Hemisphere.

The Arctic tundra is an area of ​​low, flat and swampy coastal plains covered with lakes filled with melted ice.
The American tundra zone occupies the northern part of the North American mainland and runs from Northern Alaska along the coast of Hudson Bay to the north. In the east, where the influence of the Labrador Current affects, the tundra extends to 55-54 ° N. sh.
To the north of the distribution border of broad-leaved and coniferous trees, there are shrub tundras, where unpretentious plants such as creeping heather, dwarf and polar birch, willow, alder and low shrubs prevail.
Since the tundra of North America is located in areas where the waters of the Arctic Ocean go deep into the land, there is a very confusing picture of the wind regime, with frequent changes in direction and different strengths. Therefore, the geography of distribution of tundra plants is extremely complex. Since this area is in many ways similar to the forest-tundra and taiga, it is not surprising that, all of a sudden, for a traveler, low and bent in all directions vegetation in open places is suddenly replaced by tall trees in river valleys and at the foot of the mountains.
However, when moving northward, the predominance of real tundra with mosses, lichen, sedge and cotton grass becomes more and more noticeable, and tree tracts disappear completely.
The peculiarity of the North American tundra is the wide distribution of the arctic landscape - low, flat and swampy coastal plains. The vegetation here is sparse, with a short vegetative period and is represented mainly by mosses and lichens. It does not form an even cover and often sows cracks in the soil formed due to severe frosts. Where ice and earth are mixed, ice wedges and mounds of frost are formed, nicknamed pingo in Sulfur America.
The climate of the North American tundra is very harsh. The wind here is gaining extreme strength, it blows snow into the lowlands, where snow drifts are formed, which persist even in summer. It is because of the lack of snow on the plains that the soil freezes over and does not have time to warm up in a short summer. Over a large area, the climate of the Arctic tundra is more humid and damp than within the boundaries of the circumpolar tundra, which extends from American Alaska eastward to Canadian Quebec.
Separately, the tundra of the northwest of North America is distinguished - the Alaska Range and the St. Elijah Mountains. This ecoregion includes the mountains of the interior of Alaska, permanently covered with ice and snow. Those rare areas that remain ice-free are rocky, rocky and alpine tundra.
The occupations of the local population in the tundra of both North America and Eurasia are similar. These are reindeer husbandry (the arctic tundra becomes extensive reindeer pastures in the summer), hunting for sea animals (according to the quotas of the Ministry of Natural Resources) and fishing. Among the crafts - bone carving and sewing clothes and shoes from reindeer skins. There are no large cities in the tundra of North America.
The biggest threat to the North American tundra comes from oil and gas pipelines, hydrocarbon exploitation and global warming.
The fauna of the North American tundra is much richer in species composition than vegetation. Of large mammals, the prevailing caribou deer, brown bear, polar wolf, polar weasel, polar bear and musk ox (musk ox), small mammals - fox, arctic fox, lemming and ermine, birds - white goose, black goose, white and tundra partridge , Alaskan plantain (a bird of the bunting family) and the white owl, from marine mammals - seal, walrus, narwhal, beluga whale, bowhead whale. There are a lot of fish in the rivers: lake trout, whitefish, grayling.
However, only a very small part of the flora and fauna of the North American tundra is characteristic only of these places. It took the specialists a long time to find out. For example, at the dawn of the study of animals in North America, the caribou deer and the Eurasian reindeer were considered different species (today in America there are two subspecies of caribou - tundra and forest), and together with them - the American and Eurasian elk. Later studies of the movement of species along the Bering Isthmus, which once connected North America and Eurasia, showed that all these species are related or even identical.
There are many examples of this. The gray-haired marmot is a typical inhabitant of the mountain American tundra - the brother of the mountain-tundra Siberian black-capped marmot. The long-tailed gopher, an inhabitant of the American tundra, also lives in Siberia. The musk ox could be called a "Native American" if you do not know that it disappeared from the tundra of Eurasia during the time of primitive people who mercilessly destroyed the animal population.
In general, most of the American tundra endemics are represented by relatively young species that have recently separated from their closest relatives of the same genus.
A completely unique phenomenon for the tundra of North America is the distribution of certain species of birds that arrive here only in the summer months: among such species arriving on the Labrador Peninsula, even several species of tropical hummingbirds, junco (a genus of passerine birds from the bunting family, characteristic only for North America ), savanna bunting (only rarely found in the tundra of Chukotka), Canadian goose (the most widespread species of feathered game here).
The farther north, the poorer the fauna and the more its life is connected with the sea: these are auks and gulls nesting on the rocks, and pinnipeds with polar bears. A rare visitor from the depths of the southern tundra is the Arctic fox and snow bunting.
The problems associated with the pollution of the tundra are largely similar for different parts of it due to the nature of the minerals being developed here, their storage and transportation. Despite the strictest control and multimillion-dollar fines for leaks from oil pipelines, environmental pollution continues, deer refuse to use special passages, and road trains rip off the upper protective layer of tundra soils with caterpillars, which takes almost a hundred years to restore.

general information

Administrative affiliation: USA, Canada.

Languages: English, Eskimo.
Ethnic composition: Whites, African Americans, Indigenous peoples (Eskimos, Athabascans, Haida, Tlingits and Tsimshians).
Religions: Christianity (Protestantism), traditional religions.
Monetary units: Canadian dollar, US dollar.

Major rivers: Anderson, Horton (Canada).

Numbers

Climate and weather

Average January temperature: up to -30 ° С.

Average temperature in July: from +5 to + 10 ° С.

Average annual rainfall: 200-400 mm.

Relative humidity: 70%.

Economy

Industry: oil refining, petrochemical, food (meat-processing, flour-grinding).

Sea ports.

Agriculture: animal husbandry (reindeer husbandry).

Hunting and fishing.

Traditional Crafts: bone carving, making clothes from deer and arctic fox skins.
Service sector: travel, transport, trade.

sights

■ Natural: Gates of the Arctic National Park and Preserve (Alaska, USA), Kobuk Valley National Park (Alaska, USA), Wapusk and Yukkusayksalik National Parks (Hudson Bay Coast, Canada), Gros Morne National Park ( Newfoundland Island, Canada), Thorngat Mountains National Park (Labrador Peninsula, Canada).

Curious facts

■ Tundra plant Labrador tea has red leaves to use chlorophyll and heat from the sun to keep warm. None of the tundra animals eat it.

■ The North American tundra receives less rainfall annually than the desert.

■ The Mackenzie River was discovered and first crossed by the Scottish explorer Alexander Mackenzie in 1789. Its original name is Disappointment, which literally means “disappointment” in English. By assigning such a strange name to the river, Mackenzie expressed his own frustration at the fact that she had taken him not to the Pacific Ocean, but to the Arctic.

■ The term "pingo" as a typical North American designation for a mound of heaving first appeared in 1938. It was borrowed from the Eskimos by the Danish-Canadian botanist Alf Porslig.

■ The easiest way to get into the interior of the North American tundra is to drive along the highway along the Trans-Alaska Pipeline, which runs from Barlow to the Pacific port of Valdez and poses the greatest threat to the ecology of the North American tundra.