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THEORETICAL PART 2
Option 1. Tundra soils 2
1. Conceptual characteristic of type 2
2. Features of Genesis 2
3. Subtypes and their characteristics 3
4. Soil formation conditions 5
5. Composition and main properties 6
6. Agricultural use 12
PRACTICAL PART 13
1. Technique for field soil research 13
2. Field soil diagnostics. Soil structure 15
3. Diary describing the soil section 21
4. Soil section description form 23
REFERENCES 27
THEORETICAL PART
Option 1. Tundra soils
1. Conceptual characteristics of the type
Tundra soils- these are soils formed on permafrost, predominantly loamy deposits under conditions of a very short and cold growing season (north of the July isotherm + 10°, average annual temperatures are negative: - 4-14°C with a predominance of precipitation over evaporation) under shrubs (shrubs) -lichen-moss vegetation, characterized by a gleyed profile of type 0(T)-(A)-(Bg)-G. An important role in the genesis of tundra gley soils is played by cryogenic processes such as spot formation, heaving, and cracking.
2. Features of genesis
Major soil scientists, botanists, and geographers have repeatedly paid attention to the study of soils in the northern outskirts of our homeland. V.V. Dokuchaev (1899) identified a special “boreal-tundra” zone among the main soil zones, believing that there should be a special “polar” type of soil formation. N. M. Sibirtsev (1901) also classified tundra soils as one of the classes of zonal soils.
The type of tundra gley soils was introduced into soil taxonomy by E.N. Ivanova (1956).
Tundra gley soils are typical for the tundra landscape-geographical zone. They stretch in a strip of varying widths along the entire northern edge of Eurasia and North America. IN southern hemisphere Due to the lack of land in the corresponding latitudes, tundra gley soils are not common. In Eurasia, these soils make up 2.7% of the continent's area. In North America, their share in the soil cover is even higher - up to 4.6%. Their total area on the globe is about 2600 thousand km 2.
The tundra is divided into three subzones: the southern shrub-(moss-shrub) tundra subzone, the typical moss (cotton grass-moss) tundra subzone, and the arctic tundra subzone. Unlike the southern and typical tundras, the Arctic tundras are characterized by open vegetation cover; The dominant type of vegetation distribution, as in the Arctic zone, is polygonal-mesh.
A significant supply of dead plant residues in the tundra is due to the slow mineralization of litter, the poverty of bacterial flora, and unfavorable soil temperatures. A significant amount of energy of tundra biogeocenoses accumulates in dead organic matter. The biological cycle in the tundra can be characterized as inhibited, stagnant, with low capacity due to the low productivity and low ash content of tundra plants.
3. Subtypes and their characteristics
Tundra gley soils described in various bioclimatic provinces of the tundra zone, depending on soil formation conditions, can have quite significant differences in the structure of the profile. In the most general view The profile of a tundra gley soil on loamy deposits consists of a litter horizon (O or OA), a humus or humus horizon (A or OA/A), a gleyed transition horizon Bg, and a gley horizon G. In various subtypes of tundra gley soils, the structure of the profile can significantly change: tundra gley humus soils have a well-defined humus-accumulative horizon several centimeters thick, Tundra gley humus soils characterized by a brownish-brown smeared organic horizon with a large amount of semi-decomposed plant material, tundra gley typical soils have only a layer of litter (tundra felt) of mosses and shrubs, in tundra gley peat soils the organic horizon can reach a thickness of 10-20 cm.
Tundra gley soils can also differ in the nature of gleyization in the profile. In European tundras, gleying most often begins from the surface (surface-gley soils), in the Western Siberian tundras it is confined to horizons of rock change in granulometric composition (contact gley soils), in the East Siberian tundras gleying is often supra-permafrost in nature ( supra-permafrost-gley soils). If the gley horizon is developed well enough, then the soil is classified as gleyed; if there are only spots of gley in the profile, it is classified as gleyed. Gleyic soils are typical for the northern subzone of tundras - arctic tundras.
Micromorphological studies of tundra gley soils show that organic horizons are characterized by strong sandiness and an almost imperceptible content of the silty fraction in thin sections; The binding cement between mineral grains is an organic substance consisting of plant residues of varying degrees of humification. The surface of the mineral grains has been washed away from silty particles and films. Due to the fact that illuviation of silt into the underlying horizons is not observed, it can be assumed that the removal of silt particles is carried out by lateral runoff along loose organic horizons (horizontal supra-permafrost eluviation).
4. Soil formation conditions
Cryogenic processes in tundra gley soils affect the microstructure of the clayey substance of mineral horizons, which is characterized by a pronounced scaly structure. The formation of oriented clays of scaly form is most likely associated with prolonged freezing of the soil mass, during which the entire soil is penetrated by ice crystals and clay particles are oriented along these crystals. When slowly thawed, they maintain their orientation.
In thin sections of gley horizons, gray color dominates. In rare pores there are zones of rusty-brown oxidation. The horizons are poorly aggregated, contain little coarse plant residues, and the walls of pores and mineral grains are not washed away from clay matter. Characteristic is the accumulation of large amounts of amorphous iron compounds that permeate the oxidized areas of gley horizons. They also contain rounded concretions of iron hydroxides up to 1 mm in diameter.
The type of tundra gley soils is characterized by a weakly differentiated profile in the distribution of silt and mineral components. There are several factors that limit profile differentiation. The most important of them are: permafrost mass and moisture exchange in the profile (mixing and constant renewal), the presence of difficult-to-permeate gley thixotropic horizons, the difficulty of lateral outflow of elements due to uneven thawing of permafrost on various elements of the nano- and microrelief.
However, in tundra gley soils there are a number of processes that, although to a weak extent, contribute to their differentiation. These are the processes of gleyization, downward migration, cryogenic pull-up of substances from mineral horizons to organogenic ones and vice versa, and, finally, lateral runoff, which intensively flows along organogenic horizons during the period of maximum thawing of the profile.
5. Composition and main properties
Differences in the gross composition of the genetic horizons of tundra gley soils are, as a rule, small. In the Arctic tundras, the profile is almost undifferentiated in terms of the content of silt and sesquioxides. In the subzones of the typical and southern tundra, under favorable conditions, weak differentiation of the profile is observed (Fig. 1).
Most researchers of tundra gley soils note the predominance of coarse silt and fine sand fractions in their granulometric composition. This is a consequence of the fact that when cryolithogenesis(transformation of various rocks under the influence of permafrost processes) fine-grained products are formed mainly due to physical weathering, chemical weathering is of subordinate importance. Aggregation of clay particles may also occur, leading to the formation of dust-sized particles.
Due to weakly expressed processes of clay neosynthesis in cryogenic soils, the mineralogical composition of tundra gley soils is largely inherited from the soil-forming rocks. As a rule, hydromicas predominate among the finely dispersed minerals of the silt fraction (during soil formation on moraine and cover loams and some other soil-forming rocks). But on the Taimyr Peninsula and northwestern Alaska, for example, where soil formation occurs on marine dark-colored loams, mixed-layer minerals and montmorillonite predominate in the silty fraction of tundra gley soils.
The humus of tundra gley soils is characterized by the predominance of colorless mobile humic substances such as fulvic acids.
Rice. 1. Composition and properties of typical tundra gley soil (Taimyr)
The ratio of humic acid carbon to fulvic acid carbon ranges from 0.1-0.6. The humus composition is dominated by fractions associated with sesquioxides; a large proportion is made up of nonspecific substances (30-40%).
The mobility of humus leads to the impregnation of the profile of tundra gley soils with colorless organic matter. In the presence of a permafrost aquifer, humus compounds are mechanically retained above the permafrost and accumulate in the supra-permafrost horizon of the profile.
The reaction of tundra gley soils in different subzones ranges from acidic to slightly acidic, almost neutral. Tundra gley soils are the most acidic. southern tundra and forest-tundra. The nature of soil-forming rocks has a very significant effect on the reaction of soils. Thus, soils on marine loamy sediments (Taimyr Peninsula, for example) have a slightly acidic, almost neutral reaction. In close proximity to sea coasts The reaction of soils is influenced by the supply of salts from the sea. For example, the pH of the organic horizon of the Arctic tundras of the Yugorsk Peninsula is higher than in the mineral ones, due to the brought salts. Typically, in tundra soils, organic horizons are much more acidic than mineral ones.
The absorption capacity of tundra gley soils is small, but the degree of unsaturation with bases is high, with the exception of organic horizons. Due to the constant gleying of the profile and the absence of removal in tundra gley soils, a high content of mobile Fe (II) is observed (up to 100 mg - FeO per 100 g of soil in an extract of 0.1 N H3SO4 ) and low ORP from 200 to 500 mV.
Tundra gley soils are characterized by high density, low porosity (especially in gley horizons), and weak aeration. The low filtration capacity of gley horizons causes intense lateral flow through organic horizons.
In the Soil Map program prepared by the Soil Institute named after. V.V. Dokuchaev, tundra gley soils are called tundra permafrost gleyzems. In the Canadian soil classification and in the FAO/UNESCO system, these soils are classified as cryogenic gleysols. In the modern classification of soils in the United States, tundra gley soils can be classified into various large soil groups of the orders Inseptisols, Mollisols, and Entisols.
The main features of tundra gley soil formation, determined by the entire complex of bioclimatic conditions, are the following: low rate of destruction and change of soil-forming rocks; slow removal of weathering and soil formation products from the soil mass; weak differentiation of the profile according to the distribution of silt and mineral components; gleyization of the profile; the relative slowness of the decomposition and synthesis of organic substances and, as a consequence of this, the formation of coarse humus horizons with a significant amount of easily soluble humus compounds of fulvate nature; the significant role of cryogenic processes in the formation of the morphology and chemical properties of soils.
Studies of tundra soils were carried out by B. N. Gorodkova, Yu. A. Liverovsky, E. N. Ivanova, O. A. Polyntseva, N. A. Karavaeva, V. O. Targulyan, I. V. Ignatenko, I. B. Archegova, V.D. Vasilyevskaya and others. V.V. Dokuchaev identified tundra soils as a genetic type.
In the tundra, the nature of soil formation is determined by the widespread distribution of permafrost, which serves as an aquifer, low heat content, the short period of positive average monthly temperatures, atmospheric surface and supra-permafrost intrasoil waterlogging. For about 9 months, the soils are in a frozen state, and the “active” (seasonally thawing) layer (from 40...60 cm on loamy and clayey soils to 1.5...2.5 m on cartilaginous-gravelly and sandy soils ) - in conditions of lack of heat and waterlogging. Water and salt regimes are closed due to permafrost. Physical weathering dominates. Periodic thawing of soils, their freezing and drying of the surface contribute to the development of swelling processes, leading to ruptures of the turf and outpouring of liquefied swollen mineral mass through cracks in the crust, as well as hummock and spot formation, thermokarst and other processes. Therefore, soil horizons are unclear, mixed, bent, torn, with violations of the integrity of the soil profile or with cryopedoturbations. Permafrost processes are complicated by solifluction due to the oversaturation of the upper soil horizon during their thawing and sliding on permafrost or due to thixotropy (mobility or fluidity of the soil mass under mechanical influences, followed by spontaneous hardening). Thixotropy is associated with the development of colloidal films of silicic acid, sesquioxide hydrates (R203), and colloidal organomineral formations on soil particles. The thixotropic layer in the thawed state moves like a dough-like mass along the slope, changing the soil profile and relief.
Transformation of organic residues due to their low intake with litter, low temperatures, waterlogging, weak biochemical activity occurs weakly. Organic matter decomposes slowly, resulting in the formation of coarse organic-accumulative horizons, often peaty. Humic substances have a simple structure and are weakly condensed. Their composition is dominated by non-aggressive fulvic acids associated with sesquioxides, with an acidic reaction due to the low ash content of the litter and the low content of cations in it, especially calcium. The accumulation of humus is also observed in the supra-permafrost cold and gleyed horizon, rich in colloids and supersaturated with moisture.
Surface and supra-permafrost gleying plays an important role in soil development. Surface gleying is associated with precipitation, high air humidity, low evaporation from the soil surface. It is typical for tundra Eastern European soils with relatively high permafrost. In such soils, gleyization usually decreases with depth. In the Siberian tundra, due to stagnation of water above the permafrost horizon, supra-permafrost gleying occurs. Oversaturation with moisture and gleying cause high soil dispersion.
The type of soil in watersheds with loamy and clayey soil-forming rocks is tundra gley. Soil subtypes: arctic-tundra gley, typical tundra gley, proper tundra gley, podzolized tundra gley.
Arcto-tundra gleyic soils occupy flat plain areas. These soils are common on loamy-clayey soil-forming rocks. Arcto-tundra gleyic soils are found in the northern part of the Yamal, Taimyr, Gydansky peninsulas and east of the mouth of the Anabar River, on the islands New Earth, Bely, Sergei Kirov, Bolshoy Begichev, Lyakhovskie, off the Asian coast of the Arctic Ocean. They are represented mainly by alas, swampy, with lakes.
The vegetation on the flats is grass-sedge-forb-moss. In depressions, moss-sedge vegetation predominates, and in elevations of the polygons, bare destructive spots are observed.
The profile of arctic-tundra soils consists of the following horizons: Ao - litter of mosses, roots of sedges and other plants up to 5 cm thick, with weak peaty underneath; AoA 1 - coarse humus horizon 3...7 cm thick, brown-brown or dark brown in color with a gray tint, with a large number of roots, loamy, wet, with a sharp transition; B g - dark brown or brownish-brown horizon with reddish and bluish spots, passing from a depth of 20...30 cm into the brown horizon BC without traces of gleying. In the latter, only rare glandular veins are noted. Often the B g horizon is mistakenly noted as the G horizon, which is usually viscous and wet; C m - brown, frozen, icy soil-forming rock, rarely with crushed stone and blocks, from a depth of 40...50 cm.
According to the granulometric composition of the soil, it is loamy and clayey, sometimes sandy loam, sandy and gravelly, rocky. Due to the intense crushing of rocks during frost weathering, coarse dust predominates in them as the smallest limit of large fractions in the Arctic tundra. The humus horizon is significantly depleted in silt and physical clay.
Soils contain 3...7% humus in the AoA 1 horizon with a gradual decrease down to 2...3% in the supra-permafrost layer. In the most moist soils, a second maximum of humus (up to 12%) is observed - supra-permafrost, or retinized. In general, the soil profile is saturated humus, with fulvic humus (C tk: Sfk - 0.3...0.7). Ratio C: N - 10...20. The reaction of soils is from acidic - slightly acidic (pH aq 5...6) in the upper horizons to slightly acidic - neutral in the lower ones due to the neutralization of humus compounds. The absorption capacity is low - 15...20 mg eq/100 g of soil, and the degree of soil saturation with cations is 60...95%, depending on the soil-forming rocks. In the soils throughout the entire profile, significant amounts of mobile compounds SiO 2 and R 2 O 3 and organo-iron nodules are noted.
In the Arctic tundra, swamp and waterlogged soils are found in undrained areas, residually solodized illuvial-humus soils are found on sea sandy terraces, marsh saline and non-saline soils are found on coastal shallows, and silt-humus soils are found in floodplains.
Typical tundra gley soils (Fig., a) are formed in automorphic conditions on loamy-clayey deposits under grass-moss, moss-lichen groups. Distributed on the swampy plains of the northern part of the West Siberian Lowland, in the North Siberian, Yana-Indigirsk, Kolyma and Abysk lowlands, in the northeastern part of the Chukotka Peninsula. The plains are heavily swamped, with many swamps and lakes. The relief is complex: on the ridges it is fissured and polygonal with heaving mounds, and is significantly complicated by landslides and solifluction.
Rice. Soils of the tundra zone: a - typical tundra gley; b - tundra illuvial-humus
The profile of tundra gley soils has the following structure: Ao - living plant cushion or slightly peat litter with a thickness of 3 to 6 cm; A1 (AoA1) - coarse humus (less often peaty) horizon up to 20 cm thick, dark gray with brownish or brownish-brown, loamy, moist, contains a mass of intertwined plant roots; in spotted tundras this horizon is rudimentary or absent; the transition is uneven and noticeable; B g (G) - illuvial gleyed or gley horizon 40...50 cm thick, unevenly colored (there are many rusty and bluish spots on a brown background), loamy or clayey, wet, thixotropic; transition along the thawing boundary; G M - gley dark gray, frozen horizon with icy streaks; the soil-forming rock is located in the permafrost layer.
Thixotropy is absent only in carbonate rocks.
In the oceanic provinces, peculiar tundra soils are formed, in which peaty and peaty-humus horizons up to 20 cm thick develop. The humus content in the A1 horizon is 5... 10%, in the A0 A1 horizon 30...60%. These soils are deeply saturated with fulvic humus throughout the entire profile up to the supra-permafrost layer due to the migration of humic substances down to the permafrost. The C:N ratio is wide (30...40) due to incomplete humification of plant litter. The soil reaction ranges from acidic to slightly acidic, less often neutral. The absorption capacity is 20...35 mg equiv/100 soil. The degree of saturation with bases is 60...90%.
Actually, tundra gley soils are formed on loamy and clayey soil-forming rocks and have the following horizons: Hell - litter of mosses, lichens, stems of shrubs and cereals up to 5 cm thick; G - gley brown-gray, wet, thixotropic; transition along the thawing boundary; G M - gley, frozen horizon; the soil-forming rock is frozen, gleyed, loamy or clayey, with ice veins and lenses.
The soil reaction is acidic (pH 4.4...5.5). The degree of soil saturation with bases is low (less than 50%).
Tundra gley podzolized soils are characteristic of shrub tundras and forest tundras. They have the following morphology: Ao - slightly peaty litter up to 5 cm thick; A 1 (Ar) - coarse humus, less often peaty horizon up to 30 cm thick, brownish-brown in color, loamy, with a large number of plant roots, with a clear transition to the underlying horizon; A 2 (A 2 B) - brownish, with whitish spots, passing as an uneven border into the next horizon; B g (G) - brownish-gray color, loamy horizon, rarely thixotropic, frozen in the lower part. The soil-forming rock is frozen, gray, loamy-clayey, with icy lenses and veins.
Unlike typical tundra gley soils, they have a more acidic reaction (pH 4.5...5.5), increased hydrolytic acidity of the A 1 horizon (AT), differentiation of silt and chemical elements by profile. Mobile humus contains from 1 to 5%. The absorption capacity does not exceed 30 mg eq/100 g of soil. The degree of saturation with cations ranges from 20 to 65%.
On flats or in dry elevated areas, on sandy, sandy loamy soil-forming rocks, tundra illuvial-humus soils (podburs) are developed (Fig., b), the profile of which has a brown color, without gleying. The soils are strongly acidic and sour with humate-fulvate mobile humus, its content reaches 4...7% in the illuvial-humus-iron horizon B h f. The degree of saturation with bases, depending on the soil-forming rocks, is 40...80%. Soils have a low absorption capacity - 5... 10 mg eq/100 g of soil. They are enriched with oxides of iron, aluminum and silica.
In the oceanic provinces, tundra illuvial-humus podzolized soils develop on sandy, sandy loam and light loamy rocks under a lichen-moss cover with dwarf birch and wild rosemary.
The Ao horizon is a weakly peat pillow, under which lies the A 1 A 2h horizon (to a depth of 15 cm), and below - B h (to a depth of 20...30 cm) and B f. In the illuvial horizon B h there is a relative accumulation of fulvic humus (2...3%), and in other horizons its content is lower: from 0.2% to 1.5%. The soils are strongly acidic (pH 3.8...5.0), since the mineral part contains predominantly hydrogen in exchangeable form.
Tundra soils have unfavorable water-physical and thermal properties and low biological activity.
Frozen rocks thaw in the summer by only a few tens of centimeters. The frozen soil located below does not allow water to pass through, so tundra gley soils are waterlogged. In them, under the upper peaty horizon At there is a gley horizon B, or gley. This horizon has a bluish-gray (gray) color, sometimes with rusty spots. Gley formation occurs when the soil is waterlogged and lacks oxygen. Under the gley horizon there is permafrost.
Podzolic soils
Podzolic soils are formed under coniferous forests on and West Siberian Plains. Here the quantity exceeds evaporation. This leads to strong soil leaching and the formation of a brightened leaching horizon A2. From this horizon they are carried into groundwater organic and mineral compounds. Some of these compounds are retained in the underlying washout B. The B horizon is dense and has a rusty tint. The thickness of the soil and the amount of humus in the humus horizon A1 gradually increases from north to south.
Soddy-podzolic soils
Soddy-podzolic soils are formed under mixed coniferous-broad-leaved forests. Here, summer temperatures are higher and more plant residues enter the soil. The grass cover is well developed. Numerous grass roots in the upper part of the humus horizon A1 form turf. Hence the name of the soil - soddy-podzolic. Leaching in these soils is not as intense as in podzolic soils. They contain more humus and mineral compounds.
Permafrost-taiga soils
Permafrost-taiga soils are formed under forests in conditions of a sharp continental climate and permafrost. They replace podzolic soils east of. These have a small thickness (up to 1 m) and a special structure. They have a humus horizon A1, but no leaching horizon A2. Permafrost prevents leaching. The soils are colored brown by iron compounds. Humus is found not only in the A1 horizon, but also in the lower parts of the profile. At a depth of 50 cm its content is 5%, at a depth of 1 m - 2-3%.
Gray forest soils
Gray forest soils are formed under deciduous forests with rich grass cover. These soils do not form a continuous zone. But their intermittent strip stretches from the borders with Belarus in the west to in the east. In deciduous forests, more plant residues fall into the soil than in coniferous and mixed forests. The A1 horizon contains from 3 to 8% humus. The washout horizon A2 is not clearly defined. This is due to the fact that through soil leaching occurs only in the spring. The soil thickness is 120-140 cm. Gray forest soils are much more fertile than podzolic and soddy-podzolic soils.
Chernozems
Formed under grassy forest-steppes and steppes. The evaporation from the surface here is equal to annual quantity precipitation. However, from north to south, moisture decreases. In conditions of insufficient moisture, the soils are not washed. In the structure of chernozems, a black humus horizon of great thickness (40-80 cm) stands out. In the upper part of this horizon there is steppe felt, consisting of the remains of herbaceous vegetation. Under the humus horizon there is a transition horizon B. It has a blackish-brown uneven color. Horizon B gradually turns into soil-forming rock (C). Chernozems are the richest soils in humus.
Chestnut soils
Chestnut soils are formed under the grassy vegetation of dry steppes. Significantly less precipitation falls here than can evaporate from the surface. Due to the dry climate, the vegetation cover is sparse. Therefore, less plant residues enter the soil and less humus accumulates than in chernozems. The upper horizon A, grayish-chestnut in color, 15-25 cm thick, contains 3-4% humus. Transitional horizon B is brown-brown in color, compacted, 20-30 cm thick. Due to strong evaporation, soil solutions are pulled to the surface. With them salts are carried away, which precipitate when moisture evaporates. Thus, the chestnut soils become salinized.
Brown semi-desert soils
Brown soils are formed under conditions of a sharp lack of atmospheric moisture under very sparse vegetation. The humus horizon is brown in color and 10-15 cm thick. The humus content is only 2%. Horizon B is brown with a brown tint, dense. Soils are characterized by salinity.
The tundra is a vast area with a harsh climate. What plants are able to survive in these conditions, what soil covers permafrost, how is it used in agriculture, read this article.
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This zone of nature occupies a vast territory from the Kola to their coastline, washed by the Arctic Ocean. The tundra climate is characterized by low air temperatures, short summers and harsh winters, which last up to nine months a year.
The characteristics of the tundra-cold period are associated with the prevailing southern winds blowing from the mainland. In summer there is unstable weather with frequent and strong north winds. They bring cold temperatures and heavy rainfall, average annual quantity which reaches four hundred millimeters. Snow covers almost the soil surface all year round, up to two hundred and seventy days.
What is the soil like in the tundra? This zone is distinguished by peat-boggy and slightly podzolic soils. A characteristic feature is the presence of swamps. Their education is related to permafrost with waterproof properties.
The Russian tundra is an area with low population density. Indigenous peoples live here: Nenets, Chukchi, Yakuts, Sami and others. Their main occupation is reindeer herding. It is impossible to describe the tundra without mentioning places where minerals are mined, such as gold, apatites, nephelines, ores and much more. The railways do not meet the ever-growing needs of the population. This is due to permafrost, which prevents road construction.
What types of tundras are there?
Tundra is the forest vegetation lying above the northern limits. This is a territory with permafrost, which is never flooded by the waters of seas and rivers. It is characterized by a large extent from the north to the very south, this is reflected in climatic conditions within her zone. Therefore, the following types of tundra are distinguished:
- Arctic. They are occupied by islands with the same name, covered with mosses, lichens and rarely flowering plants. The latter are perennial herbs and small shrubs. Willow and dryad grass, often called partridge grass, are common here. Perennial grasses are represented by polar poppy, small sedge, some grasses and saxifrage.
- The distribution area of the northern tundra is the mainland coast. They differ from the Arctic ones in that the vegetation cover of this zone is closed. Ninety percent of the tundra soil is covered with green mosses and bushy lichens. Moss grows here. Flower plants are becoming more diverse. You can find green grass, saxifrage or viviparous knotweed. Shrub plants include lingonberry, blueberry, wild rosemary, willow, and dwarf birch.
- The southern tundra of Russia, like the northern one, is distinguished by a continuous vegetation cover that covers the soil in tiers. The top row is dominated by willow and the middle row by shrubs and herbs, while the bottom row is dominated by lichens and mosses.
How do plants survive in harsh conditions?
The climate of the tundra forced many plants to acquire so-called adaptations. For example, plants whose shoots trail or creep along the surface of the soil, and whose leaves are collected in a rosette, use ground layers of air. Low-growing representatives of the flora are helped by snow cover to survive.
In summer, plants struggle to retain moisture, reducing their leaves in size. Thus, the evaporating surface is reduced, which helps retain liquid. For example, the dryad and the polar willow have their own adaptations, thanks to which they survive. The undersides of the plants have thick hairs that prevent air movement. This helps reduce evaporation. The tundra is mostly inhabited by perennial plants. Some of them are viviparous, that is, fruits and seeds are replaced by bulbs and tubers. Such plants take root faster. This allows you to gain valuable time.
When is the tundra beautiful?
This occurs twice a year. The tundra is beautiful for the first time in August. As cloudberries ripen, the tundra changes color from green to red, and then, when the berries are ripe, to bright yellow. Cloudberry is a close relative of raspberries and is a perennial herbaceous plant. Its stems are not covered with thorns, and its flowers are much larger. An interesting fact is that unripe fruits are red, while mature ones are orange. Residents of the tundra value cloudberries. They make jam from its berries. The fruits are consumed soaked and steamed.
The second time the beauty of the tundra is clearly expressed in September, because this month is called golden autumn. The leaves of the trees turn yellow, making everything around sparkle. This time is loved by mushroom pickers. The soil of the tundra at this time is so favorable that mushrooms grow here that reach the height of local trees. It is noteworthy that they are not wormy at all.
Gley soils
According to their mechanical composition, they belong to heavy soils: loamy and clayey. The location is ridged glacial plains. thaws to a depth of fifty to one hundred and fifty centimeters. Tundra-gley soils are completely leached, that is, they do not contain readily soluble salts and carbonates.
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But they are rich in weathering products and humus, the content of which in the upper horizon is ten percent. The peaty and humus soil of the tundra contains forty percent humus. Different subzones have different soil reactions. In one area it is acidic, in another it is slightly acidic, and in a third it is neutral.
Morphological structure of the soil
- The top layer is a kind of litter of semi-decomposed mosses and lichens. Its thickness is three to five centimeters.
- A horizon consisting of coarse humus or humus up to twelve centimeters thick. It is a moist loam of dark brown or dark gray color with densely intertwined roots. Such soil has an uneven border and a clear transition.
- A horizon whose thickness is eight to twelve centimeters. It is called illuvial. Unevenly colored, the background is brown with rusty and pale bluish spots. This is a loamy horizon with numerous roots.
- The horizon is gley. Its thickness is twenty to twenty-five centimeters. What is the soil like in the tundra? It has vague spots of bluish color. Sometimes rusty spots are visible against the general background. This is a loamy horizon, in rare cases – thixotropic. It is characterized by moisture and a small number of roots.
- The horizon is illuvial. Its thickness is twelve to fifteen centimeters. Unevenly colored, brown background. There are dark gray and rusty spots. The horizon is loamy, fairly moist, with a small content of roots. The permafrost is visible below. Often thixotropic.
- Gley loamy horizon of dark gray color. It contains many veins of ice.
What is the phenomenon of thixotropy?
This is a state when highly moistened soils, under mechanical influence on them, are able to change their state from viscous-plastic to quicksand. After some time, the soil returns to its original state. Moreover, the humidity does not decrease. Continental tundras are rarely subject to the phenomenon of thixotropy, which decreases across subzones from north to south. This also applies to soil gleying.
Use of tundra soils in agriculture
The main industry in Arctic zone tundra is reindeer herding. Agriculture is also progressing very slowly. In some areas, they began to grow potatoes, cabbage, radishes, carrots, rutabaga and other vegetables. Some grain crops are also grown at experimental stations and state farms.
Mastering new ones land, take into account the unfavorable factors that are characteristic of tundra soils. Therefore, the main tasks of soil cultivation are their drainage, activation of biological processes, improvement of aeration, elimination of the harmful effects of permafrost, and much more. To make the soil suitable for use for agricultural purposes, it is fertilized with manure, peat, organic and mineral fertilizers. The soil of the tundra, experiencing the influence of cultivation, changes. The best indicator is a decrease in permafrost levels. Its influence on plant growth is significantly reduced.
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TUNDRA SOILS
The soil cover of the tundra reflects a unique interaction between living and inanimate nature. Either thawing or freezing again, the layers mix with each other. Plant remains (peat, humus, humus) can end up at a depth of more than a meter. As a result, clay and loamy soils in the tundra often have a curious property. Until you stay in one place, nothing special is noticeable. But as soon as you stand for a while, the ground begins to sag and can even suck you up to your ankles or knees. You have to jump out of your boots so as not to completely plunge into the quagmire.
The most common soils in the tundra are gley (structureless) soils with a bluish and rusty color. On flat plains Peat bog soils are common. However, the layer of peat in them is small, only 10-50 cm, because in the conditions of a short, cold summer, the “harvest” of bog mosses and sedges from which peat is formed is insignificant. In drier sandy areas, less fertile soils are formed - podzols and podburs.
In the tundra you can rarely see real rocks: temperature changes and freezing water crush rocks that are not protected by soil and vegetation. Usually the slopes and peaks are covered with boulders or sheb-nem. Sometimes they have no soil at all and are decorated only with a crust of lichens. But next to the stone placers, where fine earth accumulates (soil particles less than 1 mm) and there is protection from the cold wind, a tundra oasis appears. Grass grows in it, turf is formed - the top layer of soil with a dense interweaving of living and dead plant roots, and dark accumulations of humus (from the Latin humus - “earth”, “soil”), or humus, appear - the soil nutrient that is formed during the decomposition of organic residues. Birds often use such nooks for nesting.
