Soils are their main properties of mixed forests. Soil of mixed forests

What soils prevail in mixed forests, you will learn from this article.

What are the soils in the zone of mixed forests?

* Sod-podzolic soils

Soddy-podzolic soil is widely formed in mixed forests. Thanks to weather conditions a powerful humus-accumulative horizon has formed here, in which a small proportion belongs to the sod layer. The following elements are involved 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. The soddy-podzolic soil is enriched with silica, but at the same time practically does not contain nitrogen and phosphorus. Contains a large amount of moisture.

* Forest gray soils

Gray soil is considered a transitional soil from podzolic soil to black soil. This type was formed due to the warm climate and plant diversity. The basis for the formation of gray soils is plant particles, animal excrement, and the remains of microorganisms. 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 level of fertility is somewhat lower than that of chernozem due to the fact that high humidity leads to the washing out of some elements.

What is a mixed forest?

Mixed forests are a natural area where various types of deciduous and coniferous trees grow.

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 the frequent change of weather seasons, different types of soils have formed in these zones, namely brown, soddy-podzolic and forest gray soils. They are characterized by a high level of humus capacity.

Broad-leaved and mixed forests make up a much smaller percentage of Russia's forest zone than coniferous taiga. In Siberia, they are completely absent. Broad-leaved and mixed forests are typical for the European part and the Far East region of the Russian Federation. They are formed by deciduous and conifers trees. They have not only a mixed composition of forest stands, but also differ in the diversity of the animal world, resistance to negative impacts environment, mosaic structure.

Types and layering of mixed forests

There are coniferous-small-leaved and mixed-broad-leaved forests. The former grow mainly in continental regions. Mixed forests have a clearly visible layering (changes in the composition of the flora, depending on the height). Most upper tier- these are tall spruces, pines, oaks. Somewhat lower grow birches, maples, elms, lindens, wild pears and apple trees, younger oak forests and others. Next come lower trees: mountain ash, viburnum, etc. The next tier is formed by shrubs: viburnum, hazel, hawthorn, rose hips, raspberries and many others. Next come the semi-shrubs. Grasses, lichens and mosses grow at the very bottom.

Intermediate and primary forms of coniferous-small-leaved forest

An interesting feature is that mixed-leaved massifs are considered only an intermediate stage of formation. coniferous forest. However, they are also indigenous: massifs of stone birch (Kamchatka), birch pegs in the forest-steppes, aspen bushes and swampy alder forests (south of the European part of the Russian Federation). Small-leaved forests are very light. This contributes to the lush growth of the grass cover and its diversity. broad-leaved type, on the contrary, refers to stable natural formations. It is distributed in the transition zone between taiga and broad-leaved types. grow on the plains and on the lowest mountain belt with temperate and humid climatic conditions.

Coniferous-deciduous forests grow in more warm regions temperate zone. They are distinguished by the diversity and richness of the grass cover. Grow in intermittent stripes from the European part of the Russian Federation to Far East. Their landscapes are favorable for people. To the south of the taiga is a zone mixed forests. They are distributed throughout the entire area of ​​the East European Plain, as well as beyond the Urals (up to the Amur region). They do not form a continuous zone.

The approximate border of the European section of broad-leaved and mixed forests in the north lies along 57 ° N. sh. Above it, the oak (one of the key trees) almost completely disappears. The southern one almost comes into contact with the northern border of the forest-steppes, where the spruce completely disappears. This zone is a section in the form of a triangle, two peaks of which are in Russia (Ekaterinburg, St. Petersburg), and the third - in Ukraine (Kyiv). That is, as the distance from the main zone to the north, broad-leaved, as well as mixed forests gradually leave the watershed spaces. They prefer warmer and sheltered from icy winds. river valleys with outcrops of carbonate rocks. On them, forests of broad-leaved and mixed types gradually reach the taiga in small massifs.

The East European Plain is mostly low-lying and flat, with only occasional elevations. Here are the sources, basins and watersheds of the largest Russian rivers: Dnieper, Volga, Western Dvina. On their floodplains, meadows are interspersed with forests and arable lands. In some regions, the lowlands, due to the proximity of groundwater, as well as the limited flow, are extremely swampy in places. There are also areas with sandy soils on which pine forests grow. Berry bushes and herbs grow in swamps and clearings. This area is the most suitable for coniferous-deciduous forests.

Human influence

Broad-leaved, as well as mixed forests, are subject to various influences from people for a long time. Therefore, many massifs have changed a lot: the native vegetation has either been completely destroyed, or partially or completely replaced by secondary rocks. Now the remains of broad-leaved forests, which have survived under severe anthropogenic pressure, have a different structure of flora changes. Some species, having lost their place in indigenous communities, grow in anthropogenically disturbed habitats or have taken up intrazonal positions.

Climate

The climate of mixed forests is quite mild. It is characterized as relatively warm winter(average from 0 to -16°C) and long summer (16-24°C) compared to the taiga zone. Average annual quantity precipitation - 500-1000 mm. It exceeds evaporation everywhere, which is a feature of the pronounced leaching water regime. Mixed forests have such feature as a high level of grass cover development. Their biomass averages 2-3 thousand c/ha. The level of litter also exceeds the biomass of the taiga, however, due to the higher activity of microorganisms, the destruction of organic matter is much faster. Therefore, mixed forests are thinner and have a higher level of litter decomposition than taiga coniferous forests.

Soils of mixed forests

The soils of mixed forests are diverse. The cover has a rather variegated structure. On the territory of the East European Plain, the most common type is soddy-podzolic soil. It is a southern variety of classical podzolic soils and is formed only in the presence of loamy soil-forming rocks. The soddy-podzolic soil has the same profile structure and a similar structure. It differs from the podzolic one in the lower massiveness of the litter (up to 5 cm), as well as in the greater thickness of all horizons. And these are not the only differences. Soddy-podzolic soils have a more pronounced humus horizon A1, which is located under the litter. Appearance it differs from a similar layer of podzolic soils. Top part contains rhizomes of grass cover and forms turf. The horizon can be colored in various shades of gray and has a loose structure. The layer thickness is 5-20 cm, the proportion of humus is up to 4%. The upper part of the profile of these soils has an acidic reaction. As it deepens, it becomes even smaller.

Soils of mixed broad-leaved forests

Gray forest soils of mixed-deciduous forests are formed in inland regions. In Russia, they are distributed from the European part to Transbaikalia. In such soils, precipitation penetrates to a great depth. However, groundwater horizons are often very deep. Therefore, wetting of the soil to their level is typical only in highly humid areas.

The soils of mixed forests are better suited for farming than those of taiga. AT southern regions In the European part of the Russian Federation, arable land makes up to 45% of the area. Closer to the north and taiga, the share of arable land gradually decreases. Agriculture in these regions is difficult due to the strong leaching, waterlogging and bouldering of soils. Good crops require a lot of fertilizer.

General characteristics of fauna and flora

The plants and animals of the mixed forest are very diverse. In terms of species richness of flora and fauna, they are comparable only with tropical jungle and are home to many carnivores and herbivores. Here on tall trees squirrels and other living creatures settle down, birds make nests on the crowns, hares and foxes equip holes near the roots, and beavers live near the rivers. The species diversity of the mixed zone is very high. Both the inhabitants of the taiga and broad-leaved forests, and the inhabitants of the forest-steppes feel comfortable here. Some are awake all year round, while others hibernate for the winter. Plants and have a symbiotic relationship. Many herbivores feed on various berries, which are abundant in mixed forests.

Mixed-small-leaved forests are approximately 90% composed of coniferous and small-leaved tree species. There are not many broad-leaved varieties. Together with coniferous trees aspens, birches, alders, willows, poplars grow in them. There are the most birch forests in the massifs of this type. As a rule, they are secondary - that is, they grow in forest fires, clearings and clearings, old unused arable lands. In open habitats, such forests regenerate well and in the first years, the expansion of their areas is facilitated by

Coniferous-broad-leaved forests mainly consist of spruces, lindens, pines, oaks, elms, elms, maples, and in the southwestern regions of the Russian Federation - beech, ash and hornbeam. The same trees, but of local varieties, grow in the Far East region along with grapes and lianas. In many ways, the composition and structure of the forest stand of coniferous-broad-leaved forests depends on climatic conditions, relief and soil-hydrological regime of a particular region. Oak, spruce, maple, fir and other species predominate in the North Caucasus. But the most diverse in composition are the Far Eastern forests of the coniferous-broad-leaved type. They are formed by cedar pine, white fir, Ayan spruce, several Manchurian ash, Mongolian oak, Amur linden and the above-mentioned local vegetation species.

Species diversity of the animal world

Of the large herbivores, moose, bison, wild boars, roe deer and spotted deer (the species has been introduced and adapted) live in mixed forests. Of the rodents present forest squirrels, martens, ermines, beavers, chipmunks, otters, mice, badgers, minks, black ferrets. Mixed forests abound in a large number of bird species. Many of them are listed below, but not all of them: oriole, nuthatch, siskin, field thrush, goshawk, hazel grouse, bullfinch, nightingale, cuckoo, hoopoe, gray crane, goldfinch, woodpecker, black grouse, chaffinch. More or less large predators represented by wolves, lynxes and foxes. The mixed forests are also home to hares (hare and hare), lizards, hedgehogs, snakes, frogs and brown bears.

Mushrooms and berries

The berries are represented by blueberries, raspberries, lingonberries, cranberries, blackberries, bird cherry, wild strawberries, stone berries, elderberries, mountain ash, viburnum, dogrose, hawthorn. There are many forests of this type. edible mushrooms: boletus, white, valui, chanterelles, russula, mushrooms, milk mushrooms, boletus, volnushki, various rows, boletus, mossiness mushrooms, mushrooms and others. One of the most dangerous poisonous macromycetes are fly agarics and pale grebes.

shrubs

The mixed forests of Russia abound in shrubs. The understory layer is unusually developed. Oak massifs are characterized by the presence of hazel, euonymus, forest honeysuckle, and in northern zone- buckthorn brittle. Rose hips grow on the edges and in light forests. In the forests of the coniferous-broad-leaved type, liana-like plants are also found: new fence, climbing hops, bittersweet nightshade.

Herbs

Mixed forest grasses (especially coniferous-broad-leaved type) have a large species diversity, as well as a complex vertical structure. The most typical and widely represented category is the mesophilic nemoral plants. Among them, representatives of oak broad grass stand out. These are plants in which the leaf plate has a significant width. These include: perennial forestry, common gout, obscure lungwort, May lily of the valley, hairy sedge, yellow greenfinch, lanceolate chickweed, nomad (black and spring), amazing violet. Cereals are represented by oak bluegrass, giant fescue, forest reed grass, short-legged feathery, spreading pine forest and some others. The flat leaves of these plants are a variant of adaptation to the specific phytoenvironment of coniferous-deciduous forests.

In addition to the above perennial species, these massifs also contain herbs of the ephemeroid group. They carry their growing season to spring time when the illumination is at its maximum. After the snow melts, it is the ephemeroids that form a beautifully blooming carpet of yellow anemones and goose onions, purple corydalis and lilac-bluish woods. These plants are life cycle in a couple of weeks, and when the leaves of the trees bloom, their aerial part dies off over time. They experience an unfavorable period under a layer of soil in the form of tubers, bulbs and rhizomes.

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

Climate. Moderately warm with mild winters and significant rainfall (600–1000 mm). The moisture coefficient is greater than one (1.1–1.3), the water regime is leaching.

Relief. Flat.

Vegetation. Broad-leaved forests of beech, oak, hornbeam, ash, linden, maple, fir, cedar and Sayan spruce. The forests are light, sparse, so a dense grass cover is formed in them.
Soil-forming rocks- these are predominantly alluvial-deluvial and alluvial deposits, loess, loess-like and mantle loams, rocks enriched in carbonates or silicate bases.

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

In addition, the process of intrasoil gleying is manifested in burozems; enrichment of the illuvial horizon with silty 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 to horizon B from above under the conditions of the flushing regime by lessivage. The podzolic process is not expressed in burozems. This is due to the fact that in deciduous forests, along with the litter, a large amount of ash elements returns to the soil, including calcium salts, 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; А1 (20–40 cm) – humus-accumulative brownish-gray, granular structure; B (80–120 cm) – illuvial, clayey, bright brown in color, buffy structure; C - soil-forming rock.

Physico-chemical characteristics 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), base saturation is high (V can be up to 80–90%). Worst performance have podzolized burozems.

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

Mixed forests are natural area, where a mixture of conifers and deciduous trees(in the presence of an admixture of more than 5% of plants of another type). All life forms of vegetation occupy their ecological niches, forming a unique balance. A thicket with a diverse composition of trees is resistant to environmental influences, has a mosaic structure and a diverse flora and fauna. If a favorable combination of coniferous and hardwood, such heterogeneity is more productive than homogeneous.

Characteristics and features of the natural zone of mixed forests.

There are coniferous-small-leaved and coniferous-broad-leaved forests. The former, growing in the taiga regions of Eurasia, are not durable. They precede the change from small-leaved groves to indigenous coniferous forests or broad-leaved oak forests. And coniferous-broad-leaved thickets are considered a sustainable natural formation. Such ecosystems develop cyclically, with a temporary predominance of conifers or a number of deciduous species. Depending on the climate, terrain, soil and hydrological regime, the composition of trees varies. Often there are spruce, pine, fir, oak, beech, linden, maple, ash, aspen, birch and other species in various combinations.

Mixed forest areas are formed in temperate climate zone (temperate continental climate) with a clear change of seasons - relatively hot summers and cold winter. The average annual rainfall here usually reaches 600-700 mm. With insufficient evaporation, excessive moisture and waterlogging of the area is observed.

Coniferous-deciduous forests grow in North America (in most of Canada, in the north of the USA), in the western part South America, Eurasia (Europe, Russia, Central Asia), Great Britain, in the north of Japan. This natural zone in the south is replaced by forest-steppe or broadleaf forest, and to the north it turns into coniferous.

Under mixed forests with a predominant share of deciduous species, gray and brown forest soils. They are characteristic more content humus than in podzolic taiga varieties. If conifers are the main ones, then soddy-podzolic soils of low fertility, with high acidity and excessive moisture, predominate.

In Russia, accurate records of the number of mixed forests are not kept. On average, they account for up to half of the total area of ​​the country's forest fund. They grow throughout Western Europe, reaching Eastern, where they border on the taiga along a conditional line from St. Petersburg to Nizhny Novgorod. Further to the east, a narrow strip stretches to the Urals.

To the mountains of the Far East and North America. The rocks of these vast areas can make up a rich collection of any museum. The forests themselves are also diverse - from northern tundra to broad-leaved oak forests. Soil formation factors are diverse.

In the tundra forests and in the northern part taiga zone, where the climate is very humid, strongly waterlogged and not very waterlogged alternate. The wettest soils are under swamps, which are filled with water even in the short northern summer. Under these conditions, the dying remains of plants do not have time to decompose, as a result of which peat accumulates and swamp peat soils are formed. Moreover, unlike tundra swamps, the depth of peat can reach up to ten meters.

If the upper, peaty, soil layers under the forest have time to dry out a little, but the middle and lower, mineral ones, do not, then gley taiga soils (gleyzems) are formed. Gley soils are formed with limited access to oxygen and excessive moisture. They have bluish-gray, blue and even blue colors. There are many such soils on the flat plains of Western Siberia. AT Eastern Siberia the soils under the forest are affected by shallow permafrost, which does not let thaw and rain water. The soils here are waterlogged and are called gley permafrost-taiga.

In the southern part and under waterlogged soils, there is much less waterlogged soil, and in podzolic soils a humus horizon appears, and sometimes sod. This is due to the fact that in these more southern regions grows in the forests herbaceous plants, and the remains of their numerous roots are mixed by worms, moles and other soil animals (there are much more of them here than in the taiga north) with mineral matter. In addition, almost all soils in these areas were plowed in ancient times, i.e., organic and mineral substances were also actively mixed. Such soils with a humus horizon, a horizon of leaching of iron and clay particles, as well as a brown leaching horizon are called soddy-podzolic. Waterlogged soils of marshy meadows with humus and gley horizons are also found in this part of the forest zone. They are called sod-gley soils. These two types of soils are very widespread, especially in the European part of Russia.

In the warmest part of the forest zone of the temperate zone - in deciduous forests- gray forest soils and brown forest soils (burozems) are formed. Gray forest soils are a cross between soddy-podzolic soils of mixed forests and forest-steppes and steppes. They form in warmer, drier and more abundant soils than soddy-podzolic soils. plant residues and there are more soil animals mixing them, so the humus horizon in them is thicker (greater in thickness) and darker. However, in winter it forms so stable that every spring, when snow melts, the soil experiences a kind of blow - it is actively washed out. As a result, washout and washout horizons appear in it. Brown forest soils are soils of a warmer, but no less humid climate than sod-podzolic. They are common in Western and Central Europe, on the northeast coast, in the very south of the Russian Far East and in. For these soils, conditions are more favorable here than in the regions continental climate: no hot and dry summer, no stable snow cover. Thus, brown forest soils are moistened almost evenly throughout the year. With such a “slow” life, organic residues decompose gradually, the emerging humus acquires a more brown - brown color, and without annual strong washing, the iron leaching horizon may not form at all. Burozems are also found in a more severe climate, in the middle and southern regions of the taiga, but they are always located on iron-rich rocks. There is no washout horizon here for the same reasons as in podburs.

Many different soils are formed at the boundaries between their main types. So, at the transition between bog and podzolic soils, bog-podzolic soils are formed. Gley-podzolic soils can occur between gley soils and podzolic soils. The names themselves already indicate that in these soils there are signs of both one and other types of soils. Thus, in bog-podzolic soils there is a peaty (less than 15 cm) or even peat (greater than 15 cm) horizon, and in the leaching horizon of gley-podzolic soils, gray and rusty spots indicate a gley process. Similar soils - "border guards" are characteristic of many types of forest soils. So, for example, podzolic-brown soils "border" between burozems and soddy-podzolic soils.

Limestones are light dense sedimentary rocks widespread on Earth, from which white-stone cities used to be built. They consist mainly of calcium carbonate, the formula of which is CaCO3. Limestones are easily destroyed, and their fragments are often mixed with other loose rocks that are often found, for example, clayey glacial deposits. There are many soils on carbonate rocks, i.e., rocks containing calcium carbonates. If the content of calcium carbonates is low, then the soils almost do not differ from those formed on the same rocks, but without lime. If there are a lot of calcium carbonates in the rock, the soils are completely different from their neighbors. And that's why. Carbonates are salts of a very weak acid, so they give an alkaline reaction to the soil solution. This neutralizes organic acids coming from organic residues. In alkaline conditions, other than in usually acidic forest soils, soil organisms, which decompose plant remains in a different way. As a result, calcium is the first to combine with organic matter, giving the humus a dark gray color, so these "foreigners" - soils on calcareous rocks in the zone of mixed forests - resemble chernozems in their upper layer. In the people they are called so - chernozems. Scientifically, these are sod-calcareous soils, because they differ from real steppe chernozems in lower soil horizons, often stony and even rocky. And they are also called rendzins, which in Polish means "soils that grind when plowing