1. Geographical location.
2. Geological structure and relief.
3. Climate and water.
4. Soils, flora and fauna.
Geographical position
Altai-Sayan mountainous country is located in the center of Asia and occupies the western part of the mountains Southern Siberia... The borders of the country are defined by faults and displacement of block structures during tectonic movements. The border with the West Siberian Plain runs along fault benches with a height of 300-500 m. In the northeast, there is a border with the Central Siberian Plateau. In the southeast, the country borders on the Baikal mountainous country along the rift zone - the Tuva graben. In the southwest, the border runs with Kazakhstan and Mongolia. The country includes: mountain systems and intermontane basins - Altai, Salair Ridge, Kuznetsk Alatau, Western and Eastern Sayan Mountains, Tuva Upland, as well as Tuvinskaya, Minusinskaya, Kuznetskaya and others.
Geological structure and relief
Altai-Sayan folded-block geostructures frame the Siberian platform from the southwest. The most ancient mountain building movements took place at the end of the Proterozoic. As a result, the Sayan-Baikal fold belt was created in the east. At the beginning of the Paleozoic, the structures of the Caledonian folding (Sayan and most of Altai). The last folding - Hercynian - manifested itself in the west of the country. By the beginning of the Cenozoic, the structures were severely destroyed and experienced new tectonic movements in the Cenozoic: faults and volcanoes formed, high uplifts (up to 3000 m) and intermontane basins were created. These processes led to the formation of folded-block mountains, highlands and intermontane basins. The country experienced ancient glaciations, therefore, glacial forms (kars, troughs, moraine hills, etc.) have been preserved in the relief. Erosional landforms are also widespread. External (exogenous) processes determined the morphological zonation: the first belt - high mountains with nival-glacial forms (the summits of Altai, Sayan, etc.); the second belt is the ancient peneplain, these are high mountain ranges with a leveled surface; the third belt - erosion-denudation low mountains. The direction of the country's mountain ranges is different. Altai has the shape of a fan, deployed to the northwest. Highest peak- Belukha Mountain (4500 m). Kuznetskiy Alatau and Salairskiy ridge are stretched from southeast to northwest, parallel to each other. The Western Sayan has a northeastern direction and runs almost perpendicular to the Eastern Sayan. Average heights are 1000-3000 m. The Western Sayan drops abruptly to the Minusinsk and Tuva basins. Eastern Sayan is a watershed between the basins of the Angara and Yenisei rivers.
Climate and water
The climate of the country is sharply continental, with a very cold winter and warm (in the hollows) summer. The climate is influenced by continental air temperate latitudes, mountainous terrain and western transfer air masses, which is most pronounced on the windward slopes. The Tuva depression is characterized by the greatest continental climate. In winter, the climate of the country is influenced by the Asian High. Average January temperatures vary from -18˚C in the Altai foothills to -30˚C in the Tuva basin. Are characteristic temperature inversions... On the windward slopes of Altai and Sayan, up to 2 meters of snow falls. Average July temperatures range from + 12˚C + 14˚C in the mountains and up to + 20˚C in the foothills and hollows. Annual precipitation ranges from 250 mm in depressions to 2000 mm in the mountains on the windward slopes.
The river network is well developed. V Altai-Sayan country the sources of the Ob and Yenisei rivers and many of their tributaries are located. All rivers are mountainous. Food is mixed snow, rain, and for some rivers also glacial. High water from May to July. The warm period accounts for up to 80-90% of the annual runoff. Most large rivers: Biya, Katun, Chulyshman, Bolshoi Yenisei, Maly Yenisei, etc. There are many lakes in Altai, most of which are located in ancient glacial crusts. But most large lake- Teletskoe - has a tectonic origin. It is mountainous and lies at an altitude of 436 m above sea level. The lake is 78 km long, the average width is 3.2 km. Maximum depth 325 m (the second deepest in Russia), many rivers flow into it (Chulyshman and others), and the Biya river flows out. This mountainous country has developed modern glaciation... Nai large quantity glaciers in Altai - about 1500 (area 910 km2). In the Sayan Mountains, glaciation is less common, only in the east. The height of the snow line rises from 2300 m in the west to 3000 m in the east.
Soils, flora and fauna
In the distribution of soil vegetation the altitudinal zonation is distinctly traced. At the foothills of Altai, the Salair Ridge, the latitudinal strike of the Russian steppes ends and the steppes enter the slopes of the ridges, up to 500 m and into intermontane basins. There are steppes at the foothills of Altai and the Salair Ridge, but they are especially widespread in the Tuva Basin. The soils are dominated by chernozem, in the east, in areas of dry steppes, chestnut. Foothill steppes - herb-turf-grass; from forbs (geranium, iris, anemone, etc.) and from cereals (feather grass, fescue, fine-legged); there are shrubs (honeysuckle, wild rose, caragana, bean, meadowsweet, etc.). In the mountain steppes, edelweiss, astragalus, shark fish, etc. appear. Tuvinian steppes are drier - small sod-cereal with the presence of tansy, serpentine, couch grass, wormwood, and shark fish. Forests cover the slopes of the mountains, they replace the steppes and rise to an altitude of 1800-2400 m.On the most humid slopes they grow spruce-fir forests with an admixture of aspen on mountain sulfur forest soils, as well as on mountain podzolic soils. Sometimes cedar is found in them. On the inner slopes of mountains with a more continental climate, larch forests with an admixture of pine and cedar grow on podzolic soils, and in permafrost regions - on permafrost taiga podburs. These forests rise most high on the slopes of the mountains up to 2000-2500 m. Above the forests there is a high-mountain belt of shrubs (dwarf birches) - dwarf birch, juniper and cedar dwarfs, willows, red currants, honeysuckle. Even higher are subalpine meadows on mountain meadow soils. Here grow grasses (hedgehog, bluegrass, oats), umbrella, highlander, etc. Subalpine meadows are gradually turning into low-grass alpine, consisting of brightly colored flowers: Siberian catchment, lights, pansies, anemones, poppies, buttercups, gentians, etc. cover mountain tundra (from mosses and lichens on tundra-mountain soils) and stony placers, in some places there are glaciers.
The fauna is characterized by great diversity. This is due to the variegation of modern landscapes from mountains to plains, the history of their formation and the border position of two zoogeographic regions: European-Siberian and Central Asian. Therefore, the animal world consists of taiga, steppe and mountain-tundra species. The taiga fauna predominates in the north and west of the country. it Brown bear, wolverine, lynx, wolf, fox, Siberian weasel, sable, chipmunk, squirrel, flying squirrel, ermine, otter, white hare, elk, red deer, musk deer. From birds - wood grouse, hazel grouse, nutcracker, deaf cuckoo, shchur, woodpeckers, owls, falconies, etc. Steppe fauna gravitates to the south, intermontane basins, especially Tuva. There are numerous gophers, Mongolian marmot, pikas, jerboa, tolai hare, corsac fox, manul cat, dzeren antelope. From birds - red duck, demoiselle crane, Mongolian bustard, saja, Mongolian horseback and others. Argali ( Mountain sheep), Mountain goat, reindeer (mountain subspecies), snow leopard (leopard), Altai vole, pika; from birds - snowcock, mountain turkey, ptarmigan, mountain horse, Altai finch, red-billed jackdaw, etc.
Nine reserves have been created within the country: "Stolby", Altai, Katunsky, Sayano-Shushensky and others.
The climate of the foothills of the Southern Altai and the valley of the Bukhtarma River is the warmest of all Altai regions. Along the southern border on the slope of the Zaisan depression, the sum of temperatures above 10 0 is 2400 0, and the duration of the period with these temperatures reaches 150 days. Average July temperatures are 20 - 22 0, January - 17, - 20 0, absolute maximums and minimums 40 - 42 0, - 45 - 54 0. In the mountains, the average July temperatures drop to 7-10 0. The distribution of precipitation throughout the province is uneven, from 200 mm per year in the southern foothills to 700 mm in the mountains. The maximum precipitation occurs during the warm season. The thickness of the snow cover in the foothills is insignificant (20-30 cm), in the mountains it increases. On the crests of ridges above 2000 - 2500 m widespread permafrost... Due to the high altitude of the mountains, modern glaciation is developed in the province. There are glaciers on the Katunsky ridge at the head of the river. Bereli, on the ridges of the Southern Altai, Sarymsakty, etc.
In the arid steppes of the foothills, mountain chestnut soils dominate, giving way to mountain chernozems on the northern slopes of the mountains, and above by mountain-forest acidic crypto-podzolic, mountain-forest chernozem-like, non-podzolized soils and dark mountain soddy soils of forest meadows. On the southern slopes, a forest zone falls out, being replaced by a forest-meadow belt with a forest-steppe zone, and mountain-forest soils are less widespread, and the chernozems of the steppe zone give way to mountain-steppe xeromorphic leached soils. In the highlands of the eastern part of the province, mountain-tundra peaty gley and non-gleyed soils are widespread, as well as mountain meadow soils, usually also peaty or coarse-humus. Significant acidity of alpine soils is characteristic.
Due to the great dryness of the climate, the mountain steppes in the Southern Altai rise higher than in the previous province, especially on the southern slopes of the ridges (up to 1200 - 1500 m). In the middle mountains (from 1300 to 1800 m, in the east - higher), coniferous forests are widespread, alternating with cereal-forb meadows. Forests grow mainly on the northern slopes, while the southern ones are dominated by meadows and shrubs. The forests are dominated by larch, sometimes found Siberian fir, in the form of an admixture to larch or forms pure plantings. The high-altitude zone is characterized by barren sedge meadows, cuff and cobresia wastelands, moss-shrub and moss-lichen stony tundras, as well as bare rocks and stony taluses. On the highest ridges (with heights of 2300-3000m on the northern slopes and 2500-3200m on the southern), the glacial-nival zone is developed. In the landscapes of the province, the influence of the deserts of Central Asia and the semi-deserts of Central Kazakhstan is felt: there are many Central Asian species in the flora and fauna.
The climatic conditions of the province are not the same in different altitude zones and zones. In the middle and high mountains, the climate is rather humid. Average January temperatures are -17, -20 0 С, at the bottom of river valleys on some days frosts reach -50, -55 0. Summer in the lower altitude zone is relatively long and warm. The sum of temperatures above 10 0 is here 2100 - 2300 0, the duration of the period with these temperatures is 130 - 140 days. Average temperature in July 20, 21 0, maximum temperatures exceed 40 0. Annual quantity precipitation in low foothills in the west of the province up to 450mm. In the mountains, the average July temperature drops to 10 - 12 0, and the amount of precipitation increases greatly, in the upper reaches of the Uba and Ulba it reaches 1500 - 2000 mm per year. The maximum precipitation occurs during the warm period. In comparison with other parts of Altai, the West Altai province is distinguished by a significant snowiness of winter and a thick snow cover. Nevertheless, permafrost is widespread on the ridge of mountains that rise above 2200 - 2300m. There are modern glaciers on the Kholzun and Ivanovsky ridges.
The main rivers flowing through the province are the Irtysh and its right tributaries Bukhtarma, Ulba, Uba. The Irtysh runoff is regulated by dams located on the territory of the province of large hydroelectric power plants - Ust-Kamenogorsk, Bukhtarma. The rest of the rivers, starting in the mountains within the Altai region, are of the Altai type according to the regime. The rivers are fed by mixed conditions due to the melting of seasonal snow and summer rains, and only at Bukhtarma is the role of glacial nutrition significant. The wood is rafted along the rivers. Can be used for hydropower purposes. There are many picturesque freshwater lakes in the province.
In the soil cover of the western, Irtysh, part of the province, dark chestnut soils, chernozems and mountain chernozems are widespread, and chernozem soils are not very humus-rich (medium- and low-humus), but very thick. Through leached chernozems, they move higher into gray forest soils (under small-leaved forests), which are characterized by high thickness and deep leaching. Mountain forests are characterized by mountain forest acidic non-podzolized and weakly podzolized soils. Acidic mountain meadow subalpine, partly alpine soils and mountain tundra gleyed and non-gleyed soils are widespread in the highlands.
There are three high-altitude landscape zones in the province: mountain-steppe (up to about 900m abs. Height), mountain-forest (up to 1800-1900m) and alpine, mainly mountain-meadow, partly mountain-tundra with cryophilic-shrub vegetation. Shrub steppes - rose gardens are widespread in the mountain-steppe zone. The mountain-forest zone is characterized by black (cedar-spruce-fir) forests, which are replaced by larch forests in the east. The high-mountain tundra is dominated by moss-birch lichen-dryad associations.
Altitudinal zonation is a natural change in natural conditions, natural zones, landscapes in the mountains.
Mountains are the main reason for the disruption of the horizontal arrangement of natural zones on the globe. From the foothills of the mountains to their tops, the temperature decreases, the amount of precipitation increases, soils, vegetation and fauna change - there is a change in natural complexes with height. The set of altitudinal belts - the structure of zonation - depends on the latitudinal position of the mountains, their distance from the ocean and height. Changing natural zones in the mountains is often compared to moving across a plain from south to north. For example, when moving up the slopes of the Caucasus, we seem to move along the plain further and further to the north, crossing the natural zones of the East European Plain in its western part. However, above the border of the forest in the mountains there are not tundras, as in the plain, but subalpine meadows and shrubs. They are replaced by low-grass alpine meadows. The peaks of the mountains are crowned with rocks devoid of vegetation, eternal snow and glaciers.
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Rice. 2. Altitudinal zonation of the mountains of Southern Siberia |
In the mountains of Siberia, located in internal parts mainland, all high-altitude belts bear the imprint of the severity of the climate. There are no oak forests in the forest-steppe zone. They are replaced by birch and light coniferous forests that are not demanding for heat. Larch forests dominate in the mountain forest zone. Higher on the slopes, they are replaced by mountain tundra.
The mountains of the eastern outskirts of the mainland - Kamchatka, Kuriles, Sakhalin, Sikhote-Alin - are characterized by peculiar forest belts of stone birch and dwarf cedar thickets. These belts are absent in the mountains of other regions of the country.
The lower altitude zone in the mountains depends on the natural zone in which the foot of the mountains lies. The upper belt is determined by the height of the mountains. The more to the south the mountains are located and the higher they are, the more complete is the set of altitudinal zones on their slopes.
ALTITUDE LIGHTNESS (high-altitude zoning, vertical zoning), the main geographical regularity of the change in natural conditions and landscapes with height in the mountains. It is mainly due to the change in the conditions of heat supply and humidification with an increase in the absolute height. The reasons, intensity and direction of these changes differ significantly from the corresponding changes in geographic latitude.
When decreasing atmospheric pressure with height, due to a decrease in the density of air, a decrease in the content of water vapor and dust in it, the intensity of the direct solar radiation, however, the intrinsic radiation earth surface increases faster, as a result of which there is a sharp decrease in air temperature with height (on average, 0.5-0.65 ° C for every 100 m of rise).
Precipitation due to the barrier effect of the mountains increases to a certain height (usually located higher in dry areas) and then decreases. A rapid change in climatic conditions with altitude corresponds to the change of soils, vegetation, runoff conditions, the set and intensity of modern exogenous processes, landforms and the entire natural complex as a whole.
This leads to the formation of high-altitude zones, distinguished by the prevailing type of landscape (mountain-forest, mountain-steppe). Within them, according to the dominance of a certain subtype of the landscape, high-altitude belts, or high-altitude subzones (for example, belts of mixed, broad-leaved or dark coniferous forests mountain forest zone). Altitude zones and belts are named according to the type of prevailing vegetation - the most obvious component of landscapes and an indicator of other natural conditions.
Altitudinal zones and belts differ from latitudinal landscape zones and subzones in shorter length, manifestation of specific exogenous processes under conditions of strong dissection and steep slope of the relief that are not characteristic of plain landscapes (landslides, mudflows, avalanches, etc.); rubble and thin soils, etc.
Some high-altitude zones and belts have no flatland analogues (for example, a mountain-meadow zone with subnival, alpine and subalpine belts).
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MV Lomonosov was the first to write about the difference in climate and nature of mountains, depending on the proximity of the earth's surface to the "frosty layer of the atmosphere". Generalizations of the patterns of altitudinal zonality belong to A.
Humboldt, who identified the relationship between climate change and vegetation in the mountains. V.
V. Dokuchaev, who pointed to the identity of vertical zoning in the mountains and latitudinal zoning on the plains. Subsequently, in order to emphasize the identified differences in the genesis of high-altitude (vertical) zoning from latitudinal zonality, it was proposed to use the term “high-altitude zonality” in Russian landscape science (A. G. Isachenko, V.
I. Prokaev and others), widely used in geobotany and soil science. In order to avoid confusion in terminology, some Russian physicogeographers (N. A. Gvozdetsky, A. M. Ryabchikov, etc.) believe that it is better to call the pattern of distribution of vegetation with height as altitudinal zonality, and in relation to changes in natural complexes, use the term “high-altitude landscape zoning” , or "high-altitude zoning". The term "vertical zoning" is sometimes used in modern geography to characterize the deep zoning of the nature of the oceans.
The structure of altitudinal zonation is characterized by a spectrum (set) of altitudinal zones and belts, their number, sequence of location and fallout, vertical width, and altitude position of boundaries.
The type of altitudinal zonation of landscapes is determined by a natural combination of vertically alternating altitudinal zones and belts, characteristic of territories with a certain zonal-sectorial confinement (see Zonality). Influence of orographic features mountain systems(strike, absolute and relative altitude of mountains, exposure of slopes, etc.) is manifested in a variety of spectra reflecting various subtypes and variants of structures within a specific type of altitudinal zonality.
The lower altitude zone in a mountain system, as a rule, corresponds to the latitudinal zone in which this system is located. In the southern mountains, the structure of the altitudinal zonation becomes more complicated, and the boundaries of the zones shift upward. In the longitudinal sectors of one geographic zone structures of altitudinal zonation often differ not in the number of altitudinal zones, but in their internal features: the mountains of the oceanic sectors are characterized by large width high-altitude zones along the vertical, the fuzzy nature of their boundaries, the formation of transition zones, etc.; in the mountains of the continental sectors, zone changes occur faster, the boundaries are usually more pronounced.
In the mountains of meridional and submeridional striking, latitudinal zoning is more clearly manifested in the spectra of altitudinal zonality. In latitudinal and sublatitudinal mountain systems, the influence of longitudinal differentiation on the spectra of altitudinal zonality is more pronounced.
Such mountain systems also emphasize and enhance zonal contrasts due to exposure effects, often serve as climatic divisions, and their ridges form the boundaries between latitudinal landscape zones and geographical zones.
For example, for Greater Caucasus allocate Various types structures of altitudinal zonality, characteristic of the northern and southern slopes in its western and eastern parts (Figure 1).
Depending on the features of the relief, full and shortened spectra of altitudinal zonality are distinguished.
Simplification of the structure of altitudinal zonation occurs both due to the insignificant height of the ridges (loss of upper zones in low and medium-altitude mountains), and with an increase in the absolute height of the foothills of slopes and bottoms of valleys (loss of lower zones). The greatest variety high-altitude zones and belts are characterized by low and middle mountains.
In the upper tiers, the structure of altitudinal zonation is rather uniform due to the uniformity of the climate of the peaks. For example, in the Urals, at the intersection of various latitudinal zones in the lower parts of the slopes, landscapes corresponding to these zones are formed, and in upper parts dominated by mountain tundra and char, found both in the north and in the south (Figure 2). At the same time, the width of the alpine zone narrows to the south, and its border rises.
With the great length of the Urals from north to south (over 2000 km), fluctuations in the border of the alpine zone are insignificant - from 750 m in the north to 1050 m in the south.
The asymmetry of the altitudinal zonality is associated with the exposure of the slopes, that is, the difference in the spectra on the slopes of different insolation (in relation to the Sun) and circulation (in relation to the direction of movement of moist air masses) exposures.
The asymmetry of altitudinal zonality is manifested in an increase in the boundaries of altitudinal zones on the southern slopes and a decrease in the width separate zones- up to their complete wedging out.
For example, on the northern slope of the Western Sayan, the upper boundary of the taiga is located at an altitude of 1300-1350 m, on the southern slope - 1450-1550 m.Exposition differences are more clearly manifested in mountain systems with a continental climate, especially if they are located at the junction of latitudinal landscape zones.
The circulating exposure enhances the effect of insolation, which is typical for the ridges of latitudinal and sublatitudinal strike. On the other hand, the different orientation of the slopes in relation to the main transport routes of moisture-bearing air masses leads to the formation of unequal spectra of altitudinal zonality. In the area of the western transfer of moist air masses, precipitation falls mainly on the western slopes, in the area monsoon climate- in the east.
The windward slopes of the ridges are characterized by humid landscapes, while the leeward slopes are characterized by arid landscapes. In a dry climate, exposure contrasts appear brighter, especially in the middle mountains - at heights where there is maximum amount precipitation.
The inversion of altitude zones, that is, the reverse sequence of their change with altitude, is noted on the slopes framing intermontane basins and large valleys.
In areas of heat deficiency and increased moisture, the mountain slopes are usually occupied by more southern types of landscapes compared to the bottoms of the basins (for example, in the Polar Urals, tundra basin bottoms are replaced by forest tundra on the slopes). In areas of sufficient heat and a lack of moisture, valleys and basins are characterized by more southern types of landscapes (for example, in the mountains of Transbaikalia, among the forest lowlands, there are steppe basins).
The structure of the altitudinal zonation of landscapes is one of the criteria for the physical and geographical zoning of mountainous countries.
Lit .: Dokuchaev V.
C. To the doctrine of zones of nature. Horizontal and vertical soil zones... SPb., 1899; Shchukin I. S., Shchukina O. E. Life of the mountains. M., 1959; Ryabchikov A.M. The structure of altitudinal zoning of land landscapes // Vestnik MGU. Ser. Geography. 1968. No. 6; Stanyukovich K.V. Vegetation of the mountains of the USSR.
Shower., 1973; Grebenshchikov O.S.On the zonality of the vegetation cover in the Mediterranean mountains in the latitudinal zone 35-40 degrees latitude // Problems of Botany.
L., 1974. T. 12; Gorchakovsky P. L. Vegetable world high-mountainous Urals. M., 1975; Gvozdetskikh N. A., Golubchikov Yu. N. Mountains. M., 1987; Isachenko A.G. Landscape science and physical-geographical zoning. M., 1991; Avessalamova I.
A., Petrushina M.N., Horoshev A.V. Mountain landscapes: structure and dynamics. M., 2002.
M.N. Petrushina.
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Altitudinal zonality / altitudinal zoning- a regular change in natural conditions, natural zones and landscapes in the mountains as the absolute height (altitude above sea level) increases.
"Altitudinal belt", "high-altitude landscape zone" - a unit of altitudinal-zonal division of landscapes in the mountains. The high-altitude belt forms a strip, relatively homogeneous in natural conditions, often discontinuous.
Altitudinal zonation is explained by climate change with height: per 1 km of rise, the air temperature decreases by an average of 6 ° C, air pressure decreases, its dustiness decreases, the intensity of solar radiation increases, cloudiness and precipitation increase to an altitude of 2-3 km.
As the height increases, the landscape belts change, to some extent similar to latitudinal zoning. The amount of solar radiation increases with the radiation balance of the surface. As a result, the air temperature decreases with increasing altitude.
In addition, there is a decrease in precipitation due to the barrier effect.
There are partial similarities between latitudinal zones and high-altitude zones in climatic features, distribution of vegetation and soils.
But many belts cannot find complete latitudinal analogs.
For example, the belt of mountain tundra is not characterized by polar night, in contrast to the similar biome on the plain.
This determines the difference in the rhythms of hydroclimatic and soil-biological processes.
Each landscape zone is characterized by its own type of altitudinal zonation, its own belt row, characterized by the number of belts, their sequence and altitude boundaries. The full range of altitudinal zonation can be observed in large mountain ranges of equatorial and tropical latitudes(Andes, Himalayas).
The scheme of the altitudinal zonation of vegetation the globe(according to K. Troll, with additions)
Two groups of altitudinal zonation types are most distinctly distinguished: coastal and continental.
For seaside the group is characterized by the predominance of mountain-forest types of landscape in low and medium mountains and the presence of a treeless belt (alpine in broad sense words) in the highlands. For continental groups of high-altitude zones are characterized by treeless landscapes, usually with a successive change from desert in the foothills and foothills to mountain-steppe and mountain-meadow in the middle and upper levels of the mountains.
With a more detailed subdivision within these groups, several types of altitudinal zonation spectra are distinguished, maintained in vast meridional bands.
In each of these bands, not only climatic conditions are common, but also the history of nature, first of all, the commonality or connection of the foci of the formation of flora and fauna.
Coastal-atlantic the type is represented by the mountains of the Western Caucasus. The lowest is the mountain-forest belt with sub-belts of deciduous and coniferous forests. Above there is an alpine (in a broad sense) belt with sub-belts of subalpine crooked forests and meadows, actually alpine low-grass meadows and nival.
An example uralo—Tianshan The type of altitudinal zonation is the mountains of Central Asia, with a change in belts from deserts at the foothills to mountain steppes on the slopes, in places with transitions to mountain forests, meadows and alpine deserts, above which the nival belt also extends.
The name comes from the Latin nivalis - snowy, cold. A belt of eternal snows and glaciers, the highest of the high-altitude zones in the mountains. The nival belt is located above the snow line, which in tropical zone and desert regions reaches 6500 m (Andes, central Asia) and naturally decreases to the north and south, reaching the level of the World Ocean in Antarctica and the Arctic. The bottom is bordered by the alpine (in the narrow sense) belt.
Small spaces free from snow experience increased frost weathering, which leads to the presence of a coarse-detrital weathering crust (stones, crushed stone). Algae, crustose lichens, single flowering grasses settle on it. Some insects, birds, single species of rodents and predators enter the nival belts.
Located between the nival (above) and mountain-forest or alpine (below) belts.
Climatic conditions are characterized by a long harsh winter and short cold summers. Average monthly temperatures are below + 5 °. [ source not specified 480 days] Strong winds are common, blowing over the snow cover and drying up the soil surface in summer.
Often deep freezing of soils. The vegetation is moss-lichen and arctic-alpine dwarf shrubs.
In relatively warm regions replaced by alpine and subalpine belts.
In a broad sense, a high-mountainous area above the border of the forest and crooked forests.
In the understanding of botanists, it is typical of the temperate and subtropical zones of the belt and and creeping shrubs, interspersed with scree. From below it borders on the subalpine belt, on top - on the nival or mountain-tundra belt.
A zone in which they are interspersed with light forests. It combines both open landscapes and park forests and crooked forests.
Above it borders on the alpine belt, below - on the mountain-forest (in humid regions) or steppe part of the desert-steppe (in arid regions).
The subalpine belt is often considered as part of the alpine or mountain-forest. The term is used synonymously with the subalpine or alpine belt, or to combine them.
In the latter case, at the bottom it borders on the forest belt, at the top - on the nival belt.
It is a combination of different forest communities. The wettest of all mountain belts. From below it borders on the desert-steppe belt, on top - on the subalpine or mountain-tundra.
A belt with a dry climate and dominance of desert and steppe vegetation formations. Distributed in desert, semi-desert and steppe zones tropics, subtropics and temperate zone, partly in the zones of savannas and woodlands of the subequatorial belts.
In the temperate and subtropical zones, mountain steppes develop with 350-500 mm of precipitation per year, mountain semi-deserts - with 250-350 mm, mountain deserts - with precipitation amounts of less than 250 mm per year.
In tropical or subequatorial climates, these values will be 100-200 mm higher. These values are 50-100 mm higher than those for the flat regions of the corresponding biomes and climatic zones.
Within the desert-steppe belts, the change of landscapes with increasing altitude occurs as follows:
In arid regions, it borders on the top of the subalpine belt, in more humid regions - on the mountain-forest belt.
However, if the mountains rise above the belt of maximum precipitation, to which the belt of mountain forests is confined, the desert-steppe belt will be located above it.
The influence of altitudinal zonation significantly affects the economy of mountainous areas. The growing season shortens with height and other agro-climatic indicators deteriorate, it becomes difficult or impossible to cultivate heat-loving crops, and it becomes possible to cultivate cold-resistant plants.
Mountain meadows are important as seasonal pastures. In the highlands, farming conditions are complicated by a decrease in pressure, a lack of oxygen, a lower boiling point of water, etc., which creates specific difficulties in the operation of transport, in high-mountain mines, meteorological stations and other economic facilities.
In humans, a complex of high-altitude conditions causes unfavorable physiological reactions (mountain sickness).
Altitudinal zonality
Altitudinal zonation is a natural change in natural conditions and landscapes in the mountains as the absolute height (altitude above sea level) increases.
Altitudinal belt is a unit of altitudinal-zonal division of landscapes in the mountains. The high-altitude belt forms a strip, relatively homogeneous in natural conditions, often discontinuous.
The attention of naturalists and geographers has long been attracted by the change of soil and vegetation as we climb the mountains.
The first to draw attention to this as a general rule was the German natural scientist A. Humboldt (19th century).
In contrast to the plains in the mountains, both flora and fauna are 2-5 times richer in species. The number of altitudinal zones in the mountains depends on the height of the mountains and on their geographic location.
Changing natural zones in the mountains is often compared to moving across a plain from south to north.
But in the mountains, the change in natural zones occurs more sharply and contrastingly and is felt at relatively short distances. The largest number altitude zones can be observed in the mountains located in the tropics, the smallest - in the mountains of the same height as in the Arctic Circle.
The nature of the altitudinal zonation changes depending on the exposure of the slope, as well as with the distance of the mountains from the ocean. The mountains located near the sea coasts are dominated by mountain-forest landscapes. For mountains in central regions the mainland is characterized by treeless landscapes.
Each high-altitude landscape belt surrounds the mountains on all sides, but the tier system on opposite slopes of the ridges can be dramatically different.
Only at the mountain foothills are the conditions close to those typical for the neighboring plains.
Above them are "floors" with a harsher nature. Above all is the layer of eternal snow and ice. The higher the colder.
But there are exceptions. There are regions in Siberia where the climate at the foothills is more severe than on the overlying slopes.
This is due to the stagnation of cold air at the bottom of the intermontane basins.
The set of altitude zones is the greater, the further south the mountains are.
This can be seen very well in the Urals. In the south of the Urals, where the heights are lower than in the Northern and Polar Urals, there are many altitudinal belts, and in the north there is only one mountain-tundra belt.
In a very contrasting way, the altitudinal belts are replaced by Black sea coast Caucasus.
In less than an hour, a car can lift hikers from the subtropics on the coast to the subalpine meadows.
The formation of types of altitudinal zonation of mountain systems is determined by the following factors:
The geographical position of the mountain system. The number of mountain high-altitude belts in each mountain system and their altitude position are basically determined by the latitude of the place and the position of the territory in relation to the seas and oceans.
As we move from north to south, the altitude position of natural belts in the mountains and their set gradually increase. For example, in the Northern Urals, forests rise along the slopes to an altitude of 700-800 m, in the South - up to 1000-1100 m, and in the Caucasus - up to 1800-2000 m. The lowest belt in the mountain system is a continuation of the latitudinal zone located near foot.
The absolute height of the mountain system. The higher the mountains rise and the closer they are to the equator, the more altitudinal zones they have.
Therefore, each mountain system develops its own set of altitudinal belts.
Relief. The relief of mountain systems (orographic pattern, degree of dissection and evenness) determines the distribution of snow cover, moisture conditions, preservation or removal of weathering products, affects the development of soil and vegetation cover and thereby determines the diversity of natural complexes in the mountains.
For example, the development of leveling surfaces contributes to an increase in the areas of high-altitude zones and the formation of more homogeneous natural complexes.
This is one of the most important factors shaping the altitudinal zonation. With the rise in the mountains, temperature, humidity, solar radiation, wind direction and strength, types of weather change. The climate determines the nature and distribution of soils, vegetation, fauna, etc., and, consequently, the variety of natural complexes.
Exposition of slopes.
It plays an essential role in the distribution of heat, moisture, wind activity, and, consequently, the processes of weathering and distribution of soil and vegetation cover. On the northern slopes of each mountain system, the altitudinal belts are usually located lower than on the southern slopes.
The position, changes in boundaries and the natural appearance of high-altitude belts are also influenced by human economic activity.
Already in the Neogene, latitudinal zones existed on the plains of Russia, almost analogous to modern ones, but due to the warmer climate, there were no zones of arctic deserts and tundras. In the Neogene-Quaternary time, significant changes in natural zones took place. This was caused by active and differentiated neotectonic movements, cooling of the climate and the emergence of glaciers in the plains and mountains.
Therefore, natural zones shifted to the south, the composition of their flora changed (strengthening of deciduous boreal and cold-resistant flora of modern coniferous forests) and fauna, the youngest zones were formed - tundra and arctic desert, and in the mountains - alpine, mountain-tundra and nival-glacial belts.
During the warmer Mikulin interglacial (between the Moscow and Valdai glaciations), natural zones shifted to the north, while altitudinal belts occupied higher levels.
At this time, the structure of modern natural zones and high-altitude belts is being formed. But due to climate change in the Late Pleistocene and Holocene, the boundaries of zones and belts shifted several times. This is confirmed by numerous relict botanical and soil finds, as well as spore-pollen analyzes of Quaternary deposits.
A set of altitudinal zones of a macroslope (slope) mountainous country or a particular slope of a particular ridge is usually referred to as a set or range of belts.
In each spectrum, the base is the landscape of the foothills of the mountains, close to the conditions of the horizontal natural zone in which this mountainous country is located. The combination of numerous factors affecting the structure of altitudinal zonality causes a complex differentiation of the types of altitude spectra.
Even within one zone, the spectra of altitudinal zonality are often inhomogeneous; for example, they become richer as the height of the mountains increases.
The structure of the altitudinal zonation of landscapes can be complete and cut off. The cut structure is observed in two cases: at a low altitude of the mountains, as a result of which the upper landscape belts characteristic of this type of altitudinal zonation fall out (Mountain Crimea, Middle Ural and others), and in high elevations, in which even river valleys lie at a high altitude, as a result of which the lower landscape belts that are part of this type of altitudinal zonation fall out (Eastern Pamir, Central Tien Shan and some other regions).
The history of the formation of the altitudinal zonation of Russia
Formation of altitudinal zonation in the modern territory Russian Federation originates in the early Pleistocene, during the interglacial period (Valdai and Moscow icing).
Due to repeated climatic transformations, the boundaries of the altitudinal zonation have shifted several times. Scientists have proven that all modern mountain systems in Russia were originally located approximately 6 ° above their current position.
The altitudinal zonation of Russia led to the formation of mountain complexes - the Urals and the mountains of the south and east of the state (Caucasus, Altai, Baikal mountain ranges, Sayan).
The Ural Mountains have the status of the most ancient mountain system in the world, their formation presumably began in the Archean period. The mountain systems of the south are much younger, but due to the fact that they are closer to the equator, they significantly predominate in terms of altitude.
Mountain Klyuchevskaya Sopka in Kamchatka
Altitudinal zonality
Altitudinal zonation or altitudinal zoning is a natural change in natural conditions and landscapes in the mountains as the absolute height increases. It is accompanied by changes in geomorphological, hydrological, soil-forming processes, the composition of vegetation and fauna. Many features of altitudinal zonality are determined by the location of the slopes in relation to the cardinal points, the prevailing air masses and the distance from the oceans.
The number of belts usually increases in high mountains and closer to the equator.
Altitudinal zonality is due to changes in density, pressure, temperature, moisture and dust content of the air with height.
Atmospheric pressure decreases in the troposphere by 1 mm Hg. st. for every 11-15 m of height. Half of all water vapor is concentrated below 1500 - 2000 m, rapidly decreasing with increasing altitude and dust content.
For these reasons, the intensity of solar radiation in the mountains increases with height, and the return of long-wave (or thermal) radiation from the surface of mountain slopes into the atmosphere and the influx of counter thermal radiation from the atmosphere decrease. This leads to a decrease in air temperature within the troposphere, on average, by 5-6 ° С for each kilometer of altitude. The conditions for condensation of water vapor are such that the number of clouds concentrated mainly in lower layers troposphere, increases to a certain height.
This leads to the existence of the belt maximum precipitation and to their decrease at a higher altitude.
The set of altitudinal belts of a mountain system or a particular slope is usually called a belt spectrum.
In each spectrum, the base is the landscape of the foot of the mountains, close to the conditions of the horizontal natural zone in which the given mountain system is located.
There is an analogy in the change of altitude zones within the spectrum of any mountainous country, on the one hand, and horizontal geographic areas from low to high latitudes - on the other hand. However, there is no complete identity between them. For example, the tundra of the Arctic latitudes is characterized by a polar day and a polar night, and with them a special rhythm of hydroclimatic and soil-biological processes.
Alpine analogs of tundra in lower latitudes and alpine meadows are devoid of such features. Alpine regions equatorial latitudes characteristic of special landscapes - paramos (Andes of Ecuador, Kilimanjaro), which have little in common with the belt of alpine meadows.
The most complete spectra of altitudinal zonality can be observed in the high mountains of equatorial and tropical latitudes (Andes, Himalayas). Towards the poles, the levels of high-altitude zones decrease, and the lower zones wedge out at certain latitudes.
This is especially well expressed on the slopes of meridionally elongated mountain systems (Andes, Cordillera, Ural). At the same time, the spectra of the altitudinal zonality of the outer and intramontane slopes are often different.
The composition of the spectra of altitudinal zonality varies greatly with distance from the seas inland. For the oceanic regions, the predominance of mountain-forest landscapes is usually characteristic, and for the continental ones, treeless ones.
The composition of the spectra of altitudinal zonality also depends on many local conditions - features geological structure, the exposure of the slopes in relation to the sides of the horizon and the prevailing winds. For example, in the Tien Shan mountains, high-altitude zones of mountain forests and forest-steppe are characteristic mainly of the northern ones, i.e.
That is, the shady and more humid slopes of the ridges. Mountain steppes are characteristic of the southern slopes of the Tien Shan at the same levels.
Altitude zoning creates a variety of impressions and, as a consequence of the contrast of the belts, their special acuity when traveling and climbing in the mountains. Within one day, the traveler manages to visit different belts- from the belt of deciduous forests, to alpine meadows and eternal snow.
In Russia, a particularly full range of altitudinal zonality is observed in the Western Caucasus in the area of Fisht or Krasnaya Polyana.
Here, on the southern slope of the Main Caucasian ridge, rising, for example, from the Mzymta valley (500 m above sea level) to the Pseashkho summit (3256 m), one can observe the change of numerous altitudinal zones.
Oak forests, alder forests and subtropical Colchis forests of the foothills are replaced higher by beech forests with the participation of hornbeam and chestnut forests. Upper belts The vegetation is formed by dark coniferous fir and spruce forests, light pine forests, park maple forests. This is followed by crooked forests, subalpine and alpine meadows. The subnival and nival-glacial belts close the summit of the pyramid at heights of more than 3000 m.
The huge length of the Urals from north to south creates significant differences in the nature of mountains, depending on latitude, complicated by altitudinal zonality. In the structure of the altitudinal zonation of the Urals largest areas occupies a mountain-forest belt, which is represented coniferous forests on mountain-podzolic and sod-podzolic soils... These forests are separated from the mountain tundra, covering the tops of the mountains, by a strip of larch and birch woodlands and individual spots of subalpine meadows.
The climate of the Cis-Urals is significantly different from the climate of the Trans-Urals.
In the Cis-Urals falls more rainfall since air masses come here from the Atlantic; it's a warmer summer here. In the Trans-Urals, the continental climate is increasing: it is drier, and the annual temperature range increases more. The climate of the Cis-Urals is much milder than the Trans-Urals due to the influence of air masses from the Atlantic.
The difference in the set of altitude zones in the Polar and South Urals is explained by the following reasons: altitude and geographical location in a particular natural zone and in the climatic zone.
Despite the high altitude, in the Polar Urals, due to the harsh climate, there are much less altitudinal belts than in the South. Rainfall is especially high on the western slope. Subpolar Urals because of its height.
In which part of the Urals is the altitudinal zonation most pronounced?
The Subpolar Urals are the most high part Ural - has a clearly defined altitudinal zonation: from coniferous forests - at the foot, then mountain forest-tundra, tundra and loaches - mountain deserts. In the Southern Urals, the altitudinal zonation at the foot begins with deciduous forests and forest-steppes, then - mountain taiga, meadows and at the top - mountain tundra.
Here is the most complete set of altitudinal zones due to its southern position.
In the Northern Urals, due to the low altitude of the mountains, the altitudinal zonation is practically not expressed.
Within the Urals, the following natural regions can be distinguished: Polar, Subpolar, Northern, Sredny and Southern Urals, which differ from each other in the features of the structure of the relief, climate and altitudinal zoning. The Polar and South Urals differ from each other not only in the northern and southern positions, but also climatic conditions, a set of high-altitude belts, inland waters and minerals.
A - the southern part of the Polar Urals; B - northern and central part of the South Urals.
1 - a belt of cold alpine deserts; 2 - mountain tundra belt; 3 - subalpine belt: a - birch forest stands in a complex with park fir-spruce forests and meadow glades; b - subalpine larch woodlands; c - sub-mountain park fir-spruce forests in a complex with meadow glades; d - subalpine oak woodlands in a complex with meadow glades; 4 - mountain-forest belt: a - mountain larch forests of the pre-tundra type; b - mountain spruce forests of the pre-tundra type; c - mountain fir-spruce southern taiga forests; d - mountain pine and birch steppe forests derived from them; e - mountain broad-leaved (oak, lilac, maple) forests; 5 - belt of mountain forest-steppe.
The phenomenon of altitudinal zonality
The presence of mountains is one of the main reasons for breaking the law geographic zoning and the formation of azonal natural complexes. With an increase in absolute altitude, average daily and, accordingly, average annual temperatures decrease, and atmospheric pressure indicators decrease. Climatic indicators affect the formation of soils. The combination of these factors affects the development of natural complexes. Differences are also formed depending on the direction of the slope (insolation).
Definition 1
The change in natural complexes with height is called altitudinal zonality .
On the territory of Russia there are Ural mountains, North Caucasus, mountain structures of the South of Siberia .
## Altitude zonality Ural mountains
Ural mountains stretched into submeridional direction almost $ 2000 $ km and serve as a conditional border between Europe and Asia. The highest point of the Urals - mountain Narodnaya ($ 1894 $ m). The average heights of the Ural Mountains do not exceed $ 1000 m. Therefore, the Ural belongs to low mountains.
Due to the peculiarities of the geographical position, the natural complexes of the western and eastern slopes differ from each other. Due to the western transport of air masses, the western slopes of the mountains are more humid and warmer, and the eastern ones are drier and colder. In general, the natural zones of the Urals correspond to latitudinal ones, but are somewhat "shifted" to the south. The territory of the Ural Mountains is crossed by natural zones of the temperate zone from tundra to semi-deserts.
Altitudinal zonation of the North Caucasus
Greater Caucasian the ridge stretches from northwest to southeast, rising to a height of $ 5000 m in large folds. The highest points of the Main Caucasian ridge - Elbrus ($ 5642 m) and Kazbek ($ 5033 m).
Remark 1
Elbrus is the highest point in Russia.
The Caucasus as a mountain structure is located on the border of the temperate and subtropical climatic zones and serves as a barrier to the cold northern air. In the southwestern part of the mountains falls from $ 2600 to $ 4000 $ mm of precipitation per year. Here formed humid subtropics ... And on the southeastern slopes formed dry subtropics .
The mountain tops are covered perennial snows and glaciers ... Below, up to a height of $ 2000 $ m, there is a belt alpine and subalpine meadows ... Even lower, to a height of $ 1300 $ m, grow spruce and fir forests, changing to the bottom oak forests ... There are thickets at the foot evergreen shrubs and vines , and in arid places - thorny shrubs (shiblyak) .
Altitudinal zonation of the mountains of the South of Siberia
The mountain belt of southern Siberia stretches from Altai in the west to the mountain systems of Transbaikalia in the east of the country. Altai is the highest mountains of this system ( Mount Belukha ($ 4506 m) - the most high point Siberia). Along the slopes of Altai up to an altitude of $ 500 m in the north and $ 1500 m in the south steppe ... Above the steppes on the damp western slopes of Altai there are spruce-fir forests ... On the territory of the Eastern and Western Sayans, the Baikal Mountains and in the Transbaikal mountains, prevail light coniferous pine-larch forests on mountain-taiga permafrost soils. The mountain tops are covered shrub thickets of cedar dwarf ... Above the forests in Altai there are subalpine and alpine meadows , and in dry conditions of the Sayan Mountains, on the Baikal and Aldan highlands, mountain areas are covered mountain tundra with dwarf birch ... Complexes are formed on the southern slopes dry Mongolian steppes .
Since there are no higher mountain systems on the territory of Russia, the areas of altitudinal zonation do not play very much big role in nature. And the mountain steppes are undergoing significant changes due to human economic activities. Most of them are plowed up, and the rest of the territory is used as hayfields and mountain pastures. Logging is carried out on the forest slopes.
Remark 2
Mountain structures of North-East Siberia are of insignificant height. Moreover, they are located in the tundra zone. Therefore, the altitudinal zonality in northeastern Russia is not clearly expressed.
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