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Mixed forests of Russia. Plants and animals of the mixed forest

You will learn from this article which soils predominate in mixed forests.

What are the soils like in the mixed forest zone?

* Sod-podzolic soils

In mixed forests, soddy-podzolic soil is widely formed. Thanks to weather conditions A powerful humus-accumulative horizon has formed here, in which a small proportion belongs to the turf layer. The following elements participate in the formation of sod-podzolic soils:

1. Ash particles

3. Calcium

7. Hydrogen

8. Aluminum

Since the environment of this type of soil is oxidized, its fertility is not too high. It contains 3-7% humus. Sod-podzolic soil is enriched with silica, but at the same time practically does not contain nitrogen and phosphorus. Contains a large number of moisture.

* Forest gray soils

Gray soil is considered a transitional soil from podzolic soil to chernozem. This type was formed due to the warm climate and plant diversity. The basis for the formation of gray soils is particles of plants, animal excrement, and the remains of microorganisms. When mixed, they create a large layer of humus.

* Brown soils

Brown soils are also formed under the influence of a warm climate, or rather moderately hot and constant soil moisture. They have a rich brown tint. Due to the fact that a large amount of grass grows on such soils, they are sufficiently enriched with humus. But its fertility level is slightly lower than that of chernozem due to the fact that high humidity leads to the leaching of some elements.

What is a mixed forest?

Mixed forests are a natural area where different kinds deciduous and coniferous trees.

Found in mixed forests different types trees. The main species are maple, oak, linden, birch, hornbeam, pine, larch, fir, spruce. Due to the high level of humidity and frequent changes in weather seasons, different types of soils have formed in these zones, namely brown, sod-podzolic and forest gray soils. They are characterized by a high level of humus capacity.

Natural area of mixed and deciduous forests occupies a smaller area than coniferous forests. However, this complex, formed in a fairly warm and humid climate, is distinguished by a wide variety of flora and fauna.

Characteristics of the natural zone Mixed forests

Mixed forests are a transitional link between the taiga zone and deciduous forests. Name natural area speaks for itself: they grow here as conifers trees and deciduous. Mixed forests are found in Russia and the European region, South and North America, New Zealand.

The climate of this natural complex quite soft. In winter, the temperature drops to -15 degrees Celsius, and in summer it ranges from +17-24.

Compared to the taiga, summers are warmer and longer. Number per annum atmospheric precipitation exceeds evaporation, which gave rise to the appearance of deciduous trees.

A distinctive feature of mixed forests is a well-developed grass cover growing on soddy-podzolic soils.

Rice. 1. In the mixed forest zone, grass cover is very developed.

This natural zone is characterized by a clearly defined layering - a change in the type of vegetation depending on the height:

the highest tier of coniferous-deciduous trees forest areas make up mighty oaks, pine and spruce;
below are linden, birch, wild apple and pear trees;
then the shortest trees grow: viburnum, rowan;
Below are raspberry, hawthorn, and rose hip bushes;
The layering of mixed forests is completed by a variety of grasses, mosses and lichens.

The fauna of mixed forests is also diverse. Large herbivores (elk, wild boar, deer and roe deer), rodents (beavers, mice, ferrets, squirrels), and predators (foxes, wolves, lynxes) live here.

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Rice. 2. Lynx - typical representative forest predators.

Description of the broad-leaved forest zone

As you move south of the continent, they change climatic conditions, which leads to the change of mixed forests to broad-leaved ones. As a result, there are significantly fewer coniferous trees, and dominance is completely transferred to deciduous species.

Broad-leaved forests are characterized by a fairly warm climate with mild winters and long, warm summers. The amount of annual precipitation slightly exceeds evaporation, making wetlands a rarity for these areas.

Typical tree species for this zone are maple, linden, oak, beech, and ash.

In dense thickets of deciduous forests, dense tree crowns do not allow the grass cover to fully develop. The ground in such areas is covered with a layer of fallen leaves. As it decomposes, it contributes to the formation of humus and the enrichment of gray and brown forest soils.

Rice. 3. In the zone of deciduous forests coniferous trees- rarity.

The fauna of deciduous forests is no different from the mixed forest zone. However, as a result of active human activity, the number of wild animals has decreased significantly, and currently they live only in nature reserves or in remote areas.

Soils of mixed and deciduous forests

Soils of mixed and deciduous forests
In mixed forests temperate zone podzolic soils (see Taiga soils) acquire humus soil horizons. First of all, this is explained by the fact that a lot of plants grow here herbaceous plants, the remains of which are mixed by soil-dwelling animals (worms, moles, etc.) with soil minerals. Such soils with a humus horizon, a horizon of leaching of iron and clay particles, as well as a brown leaching horizon are called sod-podzolic. In the subzone of mixed forests there are also waterlogged soils of swampy meadows with humus and gley soil horizons - they are called sod-gley soils. These soil types are very widespread, especially in the European part of Russia.
In the deciduous forests of the temperate zone, gray forest soils and brown forest soils, or brown soils, are formed. Gray forest soils represent a transition between soddy-podzolic soils of mixed forests and chernozems of forest-steppes and steppes. They form in warmer and drier climates and under more abundant vegetation than soddy-podzolic soils. There are more plant residues and soil animals mixing them, so the humus horizon in them is deeper and darker. However, due to the stable snow cover, every spring when the snow melts, the soil experiences a kind of shock - it is actively washed out, so leaching and washing-out horizons are formed in it. Brown forest soils– these are soils of a warmer, but no less humid climate than the one in which soddy-podzolic soils are formed. Distributed in the West. and Center. Europe, to the northeast. coast of the USA, in the very south of the Russian Far East and in Japan. Because these regions do not experience hot, dry summers and persistent snow cover in winter, brown forest soils are moistened almost evenly throughout the year. Under such conditions, organic residues decompose gradually, forming humus acquires a browner (brown) color, and without the annual influence of snowmelt, an iron leaching horizon may not form.

Geography. Modern illustrated encyclopedia. - M.: Rosman. Edited by prof. A. P. Gorkina. 2006 .

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Soddy-podzolic soils of the zone of mixed coniferous-deciduous forests are widespread in northern regions Ryazan region. Here conditions are created for the turf process to occur, leading to the formation of a humus-accumulative horizon and a weakening of the podzolic process. This circumstance is explained by the fact that in mixed forests there are broad-leaved and small-leaved tree species, and there are many grasses in the ground layer.

Nitrogen is the leader in the biological cycle; ash elements—Ca, Mg, K, P, S, Fe, Si—are less active. Therefore, with good drainage under leaching water conditions, soddy-podzolic soils are formed. The natural fertility of these soils is low due to the acidic reaction of the environment, low degree of base saturation, low humus content, small range of active moisture, and low supply of nutrients. The predominant part of soddy-podzolic soils is located in the forest fund, their involvement in Agriculture carried out during chemical reclamation (liming, application of organic and mineral fertilizers, green manure). Deprived of vegetation, sandy varieties of these soils are subject to deflation. In burnt areas and clearings, soddy-podzolic soils often become swampy.

In the subzone of the southern taiga, with difficult natural drainage, usually in depressions, soddy-podzolic soils undergo gley formation, which leads to their transformation under conditions of stagnant-leaching water regime into bog-podzolic soils. Increased moisture is accompanied by the accumulation of coarse humus and increased eluviation processes. The increase in diagnostic signs of podzolization and gleyization is well expressed in catenas on the alluvial-outwash plains of Meshchera and in other woodlands. The composition of the catena from top to bottom along the slope as moisture increases includes the following soils: weakly podzolic > podzolic > strongly podzolic deep gleyic > podzolic gleyic > podzolic gleyic > sod-gleyic > peaty-gleyic.

Polesia was characterized by widespread in the second half of the 20th century. carrying out drainage and chemical reclamation, which significantly increased the fertility of bog-podzolic soils and increased the area of agricultural land.

Swamp soils in the region are formed mainly in the subtaiga zone on leveled areas composed of water-resistant rocks. This situation has developed mainly in the Moksha lowlands, where on ancient alluvial plains vast sandy massifs are underlain by waterproof Jurassic clays.

Swamps and marsh soils are formed under conditions of stagnant water regime with excess surface, ground or mixed moisture. The nature water nutrition and the provision of mineral nutrients, swamps are divided into upland (oligotrophic), transitional (mesotrophic) and lowland (sutrophic).

The formation of raised bogs occurs on watersheds and is associated with surface swamping, when atmospheric ultra-fresh water accumulates in various depressions. In addition, raised bogs can form when driftwood builds up on lakes with relatively steep shores. As the peat layer grows, swampy peat soil gradually forms. Oligotrophic peat is formed mainly by sphagnum mosses. Under conditions of swamping by atmospheric waters, bog high peat soil acquires low ash content (0.5 - 3.5%) and a very acidic reaction of the environment (pH = 2.8 -3.6). Under the comb of living sphagnum mosses there is a peat horizon with low permeability, above which water stagnates. All these unfavorable properties determine the low fertility of bog high peat soil.

Sometimes the formation of raised bogs is associated with swamping of land with fresh (soft) groundwater, which is explained by the rise of their level in the soil horizons. In this case precipitation, seeping through non-carbonate rocks, stagnate on moraine, cover, and lacustrine deposits with low water permeability. High groundwater levels cause excessive soil moisture and lead to the formation of peat-gley and peat soil in raised bogs.

Transitional swamps are formed by mixed swamping and have an atmospheric-soil type of nutrition. Transitional swamps may appear when water bodies become overgrown. Mesotrophic peats of transitional bogs are close in their properties and nature of use to oligotrophic peats, although the conditions for mineral nutrition of plants are more favorable due to some influence of groundwater.

Lowland swamps arise when soil moisture and overgrowth of lakes. These swamps are eutrophic and have a significant content minerals brought by groundwater. Therefore, the composition of peat-forming plants lowland swamps more diverse: sedge, reed, cattail, alder, birch, spruce, pine. Peat soils of lowland bogs are characterized by high ash content (more than 6%), slightly acidic and neutral reaction of the environment (pH = 5 - 7), and good water throughput.

The lowland swamps of Meshchera are characterized by the accumulation of swamp ore

(clusters of limonite). Swamping with hard groundwater promotes the deposition of marl, as is observed, for example, in the floodplain of the Oka and its tributaries. In the presence of mineral impurities (limonite, marl), the ash content of lowland peat can increase to 20 - 30%.

The formation of bogs and bog soils is primarily associated with the formation and accumulation of peat, which makes up the organic horizon. Peat deposition is the result of delayed decomposition of plant residues in an anaerobic environment characteristic of subaqueous landscapes. In the middle and southern taiga of European Russia, the growth of the peat horizon of soils occurs very slowly - at a rate of 1 cm per year. Over a millennium, a peat layer of about 1 m is formed on the surface of the mineral bottom of the swamp.

Under the peat horizon in bog soils there is a mineral gley horizon. Therefore, the profile of bog soils has a simple T-G structure. Depending on the thickness of the peat layer, swamp soils are distinguished on small peats (less than 100 cm), on medium peats (100 - 200 cm) and on thick peats (more than 200 cm).

Bog soils can evolve with changes in water supply conditions and under the influence of succession of peat-forming plants. For example, when groundwater is separated from the capillary fringe, the soils of low-lying bogs can transform into transitional and raised bog soils.

In the second half of the 20th century. In the Ryazan region, large-scale drainage reclamation of wetlands was carried out in order to develop grassland and agriculture. With a reclamation drainage fund of 320 thousand hectares, 100 thousand hectares were drained, including about 40 thousand hectares with closed drainage. The main tracts of drained land are located in the northern part of the Ryazan region, i.e. in the Meshcherskaya and Mokshinskaya lowlands, as well as in the Oka floodplain.
Drainage of low-fertility soils of raised and transitional bogs is considered inappropriate. Therefore, after drainage, the sphagnum peat deposit is used for fuel, composts, and bedding for livestock. The natural, undrained state of these swamps allows them to be preserved as water protection areas, valuable hunting grounds, berry fields, and medicinal herb plantations.

Basically, the objects of reclamation were eutrophic soils of lowland swamps, capable of providing farmland plants with elements of mineral nutrition.

The involvement of drained lowland swamp soils in agriculture causes a number of negative environmental consequences, which is associated with their hydrothermal and pyrogenic degradation.

A decrease in the moisture content of these soils after drainage reclamation leads to shrinkage of the peat deposit, an increase in the temperature of organic horizons, an increase in soil aeration, a change from a reducing environment to an oxidizing one, an increase biological activity. Under new hydrothermal conditions, peat (especially grassy and mossy) quickly decomposes with the formation of carbon dioxide, water, and nitrates. An increase in the concentration of carbon dioxide in the ground layer causes a local “greenhouse effect”, which further increases the temperature of the peat. Tillage and the type of crop rotation also have a noticeable effect on the hydrothermal and biochemical degradation of drained peat soils. As a result, the natural process of conservation of carbon and nitrogen in the organic matter of bog soils is replaced by the irreversible loss of this chemical element due to the mineralization of peat, the removal of agricultural crops, wind erosion, and leaching with groundwater. The peat horizon of soils decreases most rapidly in row crop rotations (at a rate of up to 3 cm per year), i.e. When cultivating vegetables and potatoes, the meter-long peat deposit formed over a millennium will disappear within 35-40 years. In its place will be underlying mineral rock. In woodlands one should expect the appearance of low-fertility sandy gley soils.

Another type of degradation of drained peat soils up to their complete disappearance caused by pyrogenic factors. Typically, during the low-water period, devastating fires occur in drained swamp areas, often leading to complete burning of peat down to the mineral bottom of the swamps. In Polesie landscapes, peat soils are underlain by a thick layer of fluvioglacial and ancient alluvial barren gleyed quartz sands. After the peat deposit burns out, these sands come to the surface. In addition, the hypsometric level of the territory is noticeably reduced, which contributes to intensive secondary swamping of the previously drained swamp massif. It should also be noted that fires cause many negative social consequences associated with atmospheric smoke.
To protect drained peat soils from accelerated biochemical mineralization and fires, sanding is used as an agro-reclamation measure, i.e. adding sand to the arable horizon or to its surface. In order to preserve positive balance organic matter On reclaimed peat lowland soils, grass crop rotations are introduced, hayfields and pastures are created.

With insignificant accumulation of organic matter in the form of peat (less than 30%) in lowland and transitional bogs, bog mineral soils are classified as gley soils: humus-gley, sod-gley, silt-gley. The profile of these soils includes organic (At) and gley (G) horizons.

Soddy-gley soils of the subtaiga zone are classified as swampy (semi-swampy), since they are characterized by a long-term stagnant type of water regime. In this regard, soddy soils usually occupy poorly drained areas: depressions in interfluves, the foot of slopes, etc. The largest tracts of soddy-gley soils are located mainly in the northern regions of the Ryazan region.

The formation of sod-gley soils is associated with the occurrence of two soil-forming processes, namely: sod and gley, which are accompanied by biogenic and hydrogen accumulation chemical elements. The development of the turf process is due to the grassy meadow

vegetation, resulting in the formation of a powerful soil horizon with a high humus content (10-15%), high absorption capacity (30-40 m-eq/100 g of soil), significant base saturation with a neutral or slightly acidic reaction and a water-resistant structure. Gley formation is caused by prolonged stagnation of water in the soil, which is reflected in the appearance of corresponding morphochromatic features in the form of alternating dove-gray (bluish, greenish, gray) and ocher rusty spots in soil horizons and in maternal breed. Depending on the type of waterlogging (surface, ground, mixed), signs of gley formation appear in different parts soil profile (horizons Ag, Bg, G). Due to waterlogging, soddy-gley soils may contain a peaty litter, under which there is a humus horizon (At horizon).

Soddy-gley soils have a large supply of nutrients, but have an unfavorable water-air regime. After draining, these soils are introduced into agroecosystems.

The broad-leaved forest zone occupies a wide area in Eurasia. The zonal type of soils in it are forest soils, which are distributed under broad-leaved forests in the moderately warm and humid oceanic regions of the subboreal belt in Western and Central Europe, in Far East, in the Atlantic and coastal parts of North America. Especially common these soils are in Western Europe.

Climate. Moderately warm with mild winters and significant precipitation (600–1000 mm). The humidification coefficient is greater than one (1.1–1.3), water regime flushing

Relief. Flat.

Vegetation. Broadleaf forests from beech, oak, hornbeam, ash, linden, maple, fir, cedar and Sayan spruce. The forests are light and sparse, so a thick grass cover forms in them.
Soil-forming rocks- These are predominantly eluvial-deluvial and alluvial deposits, loess, loess-like and cover loams, rocks enriched in carbonates or silicate bases.

Brown forest soils (burozems). They are formed by a combination of processes of humus accumulation, gleyization, and lessivage. Deciduous forests produce litter rich in ash elements, which in humid and warm conditions lends itself to the processes of humification and mineralization with the active participation of a large number of microflora and invertebrates. As a result deep processing organic matter, a thin silty (muley) humus is formed, the so-called “soft”, in which humic acids predominate. Humic acids with iron oxides form water-insoluble compounds that structure the soil (organ-iron complexes).

In addition, the process of intrasoil gleying manifests itself in burozems, i.e. enrichment of the illuvial horizon with silt particles (secondary minerals), which are formed from primary ones as a result of biochemical and chemical processes, as well as synthesis from mineralization products. It is also possible to transfer silt particles into the B horizon from above under leaching conditions through laissez- age. The podzolic process is not expressed in brown soils. This is due to the fact that in deciduous forests, along with litter, a large amount of ash elements, including calcium salts, are returned to the soil, which neutralize humic and fulvic acids and create a slightly acidic reaction. The genetic profile of burozems is poorly differentiated into horizons and consists of the following: A0 – forest litter; A1 (20–40 cm) – humus-accumulative brownish-gray, granular structure; B (80–120 cm) – illuvial, clayey, bright brown color, ocher structure; C – soil-forming rock.

The physicochemical properties of brown forest soils vary significantly depending on the direction of soil formation and the composition of the rocks. In most soils, the reaction of the environment is slightly acidic (pH 5.0–6.5) and decreases with depth. The amount of humus in the A1 horizon can be 4–10%, the absorption capacity is quite high (E = 30–35 mg/eq/100 g of soil), the base saturation is high (V can be up to 80–90%). Podzolized burozems have the worst indicators.

Brown forests are more fertile than. They are used as arable land, hayfields, pastures and forest lands. The main measure to increase fertility is the creation of a cultivated arable horizon, the application of organic and mineral fertilizers, and liming as necessary. The best quality tree nurseries are located on brown forest soils.

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