Moisture nature of mixed forests. Mixed and deciduous forests. Climate of mixed and broad-leaved forests

At the southern border of the zone coniferous forests, about 60° N. sh. in the west of Eurasia and in the Great Lakes region of North America, broad-leaved trees join conifers. It is warmer here, humidification is no longer excessive, but sufficient due to greater evaporation. Summers are longer, but winters are cold and covered with snow. In such conditions, oaks, lindens, maples, elms, ash trees, and sometimes beeches can grow. All of them are represented in Eurasia and North America by different species.

In these coniferous-broad-leaved forests, broad herbs appear - plants with wide leaf blades dominate in the grass cover. Large litter of deciduous trees, shrubs and grass cover contributes to the formation of humus, and moderate moisture - to the accumulation of organic and mineral substances in the upper soil horizons.

As a result, soddy-podzolic soils with a well-defined humus horizon are formed. They are usually podzolized. The degree of podzolization depends on the properties of the soil and on the nature of the relief, which affects the drainage of the territory. When the water stagnates, gleying also develops.

As in every transitional band, in mixed forests on the internal structure of the vegetation cover big influence local conditions: relief, properties of surface rocks.

For example, on moraine loams in southern Sweden, the Baltic countries, in European Russia there are many forests with a predominance of spruce or pure spruce forests. Pine forests are widespread on the terminal moraine ridges and outwash plains of Poland, the Baltic States, Belarus, and Russia, composed of rocks of light mechanical composition from the surface. AT Belovezhskaya Pushcha, a large forest area located in the zone mixed forests, 50% of plantations are pine forests, and the remaining half are spruce-pine forests, spruce forests, oak-hornbeam massifs, secondary alder and aspen forests.

The heterogeneity of forests is exacerbated by selective logging.

Yes, in central regions In Russia, oak, widely used in the economy, was cut down. You can guess that it grew here in mixed forests almost everywhere, based on individual surviving specimens and the presence of shrubs and herbs characteristic of oak forests in coniferous and small-leaved forests. Clearings and fires also contribute to the replacement of polydominant forest communities by monodominant, often secondary birch and aspen forests, sometimes with an admixture of oak or spruce, and sometimes pure. The forests of this zone on both continents were also cut down for agricultural land, since soddy-podzolic soils have a certain fertility.

broadleaf forests

To the south, conifers "fall out" from the forest stand. The forests become purely broad-leaved. In this zone, the average July temperatures are 13-23°C, the average January temperatures are not lower than -10°C. Moisture conditions are different, but at least 500 mm of precipitation falls annually, and the summer is quite humid. Under such conditions, forests grow in the oceanic sectors of the continents and disappear in central parts where it is hotter and dry summer and cold winter.

Vegetation and soils

In European broad-leaved forests, the main species are pedunculate oak and European beech. They are often joined by maple, linden, ash, elm hornbeam.

These forests, sometimes with an admixture of birch, in the recent past occupied all plains and mountain slopes up to a height of 1000-1200 m in Western and Central Europe. The well-known geobotanist A.P. Ilyinsky called beech forests “the child of the oceanic climate”. On the plains, they do not enter east of Moldova. In the mountains, these forests usually grow on the northern and western more humid and cool slopes or above the oak. Oak forests, less demanding on moisture conditions, but requiring summer heat, reach the easternmost boundary of the zone and also form forest islands in the forest-steppe. The original form of oaks were evergreen species, they became deciduous in conditions of relatively low winter temperatures. Indeed, the leaves from oaks fly around later than from other trees, and sometimes dry foliage keeps on the branches all winter. Peculiar chestnut forests of southwestern Europe with an undergrowth of evergreen shrubs - holly and yew berry. They survived only in the lower mountain belt of southeastern France. There are very few forests left in Europe. Only on the slopes of the mountains there are more or less large forests. In the names of some mountain ranges there is the word "forest": Czech Forest, Thuringian Forest, Black Forest (in translation - "Black Forest"), etc. Relatively fertile brown and gray forest soils are formed under broad-leaved forests. They have a fairly thick and dark humus horizon with a humus content of 6-7%, a neutral reaction. The influx horizon has a nutty structure and humus films along the edges of structural units. with such soils, they are almost completely plowed up.

Animal world

The animal world is very diverse and rich. Wild boars, roe deer, red deer, hares, badgers, hedgehogs still live in the surviving forests of Europe, there are martens, forest cats, lynx, brown bears and some other types predatory mammals. In the forest litter and in the soil, there is an abundant fauna of invertebrates that process leaf litter. There are many insects and their caterpillars in the crowns of trees. They eat leaves and shoots, and small birds feed on them: warblers, warblers, tits. etc. There are birds and rodents that eat seeds and fruits: jays, forest mice and voles, dormice.

Peculiar broadleaf forests East Asia. Here the conditions are somewhat different: at very damp heat cold winter season. Different than in the West, was the history of the development of modern organic world. AT ice ages vegetation and animals could retreat south to their usual habitats, since there were no significant sublatitudinal mountain barriers. For the same reason, a free exchange of species between zonal groups is still possible.

Vegetation

Here it is difficult to draw a line between mixed and broad-leaved forests: conifers go far south to the subtropics. In addition, deciduous trees were cut down more intensively, and the proportion of conifers in mixed forests is predominant. But from subtropical latitudes evergreen magnolias, tulip tree, paulownias penetrated into this zone. In the undergrowth, along with honeysuckle and lilac, bamboo and rhododendron are common. There are numerous creepers: actinidia, wild grapes, vineyard, lemongrass. Bamboo and some creepers penetrate far to the north and are found even in the Far Eastern taiga. Lots of endemic plants. In addition to trees common to Europe, represented, however, by their own species, Manchurian walnut, velvet tree, and Chosenia grow here. Araliaceae are widespread. In the grass cover, along with close to European genera and even species, there are endemics: for example, ginseng, one of the Jeffersonia species (other species of this genus are common in North America). Under these forests, as well as under Western European ones, brown forest soils are formed.

In the animal world, the same features are observed as in the plant. The fauna is very rich and unique. It contains animals close to North American and tropical Asian species. Tiger, leopard, marten kharza, some species of birds and insects live from Hindustan to Far East.

There are few forested areas in East Asia. Within overpopulated China, all serviceable Agriculture The land has long been plowed up. The Far Eastern "Manchurian" flora has survived mainly on the territory of our country, but even here it is under the threat of destruction. There are remnants of these forests in mountainous areas. Better than on the mainland, forests have been preserved on the islands of the Japanese archipelago, where they occupy the lower mountain belt on about. Honshu and in the south about. Hokkaido. Here the participation of evergreen species is great and the degree of endemism in the flora and fauna is high. Forestry significantly altered the composition and structure Japanese forests, but the inhabitants of the country carefully treat their forests, especially in numerous national parks and reserves.

Similar reasons determine the originality of the broad-leaved forests of the east North America. Here, too, there are no sublatitudinal mountain barriers and free migration is possible.

The submeridional strike of the zone has led to the fact that in the north the proportion of broad-leaved species is very large and deciduous forests almost approach the forest-tundra. In the south, the admixture of evergreens increases, which penetrate far to the north. With change climatic conditions from temperate to subtropical latitudes, the participation of evergreen and thermophilic flora in general increases, and forests become humid subtropical.

In terms of diversity and preservation of relict plants, these forests are close to East Asian ones. Both have it and just common elements- tulip tree, magnolias, etc. The forests of the Southern Appalachians are especially rich, similar in structure to tropical rain forests: they are polydominant, multi-tiered, with lianas and epiphytes. In the northeastern United States and Canada, broadleaf forests are more similar to European ones. They are dominated by sugar maple, american ash, large-leaved beech. American broad-leaved forests have survived mainly in mountainous regions, but even there they have been significantly modified.

The fauna of the North American forests has features and similarities, and differences with the Eurasian ones.

There are related species: the wapiti deer is a race of red deer, but the virgin deer lives there - a representative of a subfamily endemic to America. Mice and rats are replaced in the same ecological niches hamster-like. endemic and large water vole- the muskrat, which is often called the water or musky rat. Similar to the East Asian black bear baribal. Pecan marten, raccoon gargle are endemic, gray fox that can climb trees. In the broad-leaved forests of North America, the only representative of marsupials on the Northern continents lives - the opossum, or marsupial rat. Of the endemic birds, mockingbirds, and Eurasian flycatchers and warblers are replaced by tyrannids and treeworts. In the west, South American hummingbirds penetrate to the northernmost border of the zone.

The productivity of broad-leaved forests is up to 150-200 c/ha, mixed - about 100 c/ha. In large areas of both continents, they are cut down, and the land is occupied by agricultural land. Often, during reforestation, broad-leaved species are replaced by fast-growing conifers and small-leaved species. The animals that inhabited these ecotopes are gradually disappearing, and their ranges are shrinking. The unique richest Appalachian forests and the beautiful chestnut forests of the south of France suffered, among other things. Special measures are required to protect still existing forest areas.

mixed forests– natural area temperate zone, transitional from the taiga zone to the zone of deciduous forests. Mixed forests are formed under conditions of sufficient humid climate, common in oceanic and transitional climatic regions continents in Europe, North America, South America, New Zealand, Tasmania.

This zone of mixed forests is characterized by a climate with moderately cold, snowy winter(t°average January from -5 to -14°С) and warm summer (t°average July up to +20°С). The amount of precipitation (400-800 mm per year) slightly exceeds evaporation.
Forests are coniferous-broad-leaved, and in more continental areas - coniferous-small-leaved, mainly on soddy-podzolic soils. Among conifers dominated by: spruce, pine, fir; from small-leaved species stand out: birch, aspen; from broad-leaved: oak, maple, linden, ash. Increase in share in species composition broad-leaved species occurs in the direction of removal from the poles and with an increase in climate humidity.
The animal world consists of both taiga species and species living in broad-leaved forests: hare, lynx, elk, fox, squirrel, wild boar, capercaillie, black grouse, etc.

The territory of the zone of mixed forests is one of the most economically developed. It has a high population density, big number large cities. This led to the fact that the natural vegetation of the zone was preserved only for a few large areas, a most territories are occupied by cities, agricultural lands, etc.

broadleaf forests- a natural zone of the temperate zone, formed in the humid climate of the oceanic territories of the continents. The main areas of broad-leaved forests are common in Europe and North America, where they are sometimes distinguished as southern part a single zone of temperate forests; small patches of deciduous forests exist in South America.
This zone is characterized by marine and moderate continental climate with moderately cold winter (average temperature January from -5 to -15 °С) and rather long warm summer (average temperature in July up to +22 °С). The amount of precipitation (600-1500 mm per year) is approximately equal to or slightly greater than evaporation.

The vegetation is dominated by trees with broad leaves that fall in winter. Dominant species: oak, beech, maple, ash, linden, hornbeam, chestnut and other trees that give significant shading, a dense grass cover is characteristic. Under deciduous forests, brown forest and gray forest soils are common.
In Europe, broad-leaved forests occupied the largest area. Here the most common tree is oak (petiolate, rocky and other species). In North America, broadleaf forests are prominent southeast of the Great Lakes. In South America, the zone is represented by southern beech forests in southern Chile.
Among the inhabitants of the zone there are ungulates and predators; of mammals, characteristic species are mink, black polecat, European wild cat, dormice, bison, etc. Of birds - green woodpecker, cuckoo, woodcock, pheasant.

Favorable climate and soil fertility led to active settlement and development of this natural area, the expansion of arable land and the reduction of forests, therefore, the place of natural vegetation in most of the broad-leaved forests was occupied by anthropogenic complexes.

Mixed forests together with taiga and deciduous forests make up the forest zone. The forest stand of a mixed forest is formed by trees of various species. Within the temperate zone, several types of mixed forests are distinguished: coniferous-deciduous forest; secondary small-leaved forest with an admixture of conifers or broadleaf trees and a mixed forest consisting of evergreen and deciduous tree species. In the subtropics, in mixed forests, mainly laurel and coniferous trees grow.

In Eurasia, the zone of coniferous-deciduous forests is widespread south of the zone taiga. Fairly wide in the west, it gradually narrows towards the east. Small areas of mixed forests are found in Kamchatka and the south of the Far East. In North America, such forests occupy vast areas in the eastern part of the temperate climate zone, in the Great Lakes region. AT southern hemisphere mixed forests grow in New Zealand and Tasmania.

The zone of mixed forests is characterized by a climate with cold snowy winters and warm summers. Winter temperatures in areas of the sea temperate climate positive, and as they move away from the oceans, they drop to -10 ° С. The amount of precipitation (400-1000 mm per year - approx..

Coniferous-broad-leaved (and in continental regions - coniferous-small-leaved - approx. from the site) forests grow mainly on gray forest and sod-podzolic soils. The humus horizon of soddy-podzolic soils, located between the forest litter (3-5 cm) and the podzolic horizon, is about 20 cm. The forest litter of mixed forests consists of many herbs. Dying and rotting, they constantly increase the humus horizon.

Mixed forests are distinguished by a clearly visible layering, that is, a change in the composition of vegetation along the height. Upper tree layer occupied by tall pines and spruces, and oaks, lindens, maples, birches, and elms grow below. Shrubs, herbs, mosses and lichens grow under the shrub layer formed by raspberries, viburnum, wild rose, hawthorn.

Coniferous-small-leaved forests, consisting of birch, aspen, alder, are intermediate forests in the process of coniferous forest formation.

Within the zone of mixed forests, there are also treeless spaces. Elevated treeless plains with fertile gray forest soils are called opolia. They are found in the south of the taiga and in the zones of mixed and broad-leaved forests of the East European Plain.

Polissya - lowered treeless plains, composed of sandy deposits of melted glacial waters, are common in eastern Poland, in Polesie, in the Meshcherskaya lowland and are often swampy.

In the south of the Far East of Russia, where seasonal winds - monsoons - dominate within the temperate climatic zone, on brown forest soils mixed and broad-leaved forests grow, called the Ussuri taiga - note .. They are characterized by a more complex longline structure, a huge variety of plant and animal species.

In the mixed forests of North America, white and red pine are often found among coniferous trees, and birch, sugar maple, American ash, linden, beech, and elm are often found among deciduous trees.

The territory of this natural zone has long been mastered by man and is quite densely populated. Agricultural lands, towns, cities are spread over large areas. A significant part of the forests has been cut down, so the composition of the forest has changed in many places, and the proportion of small-leaved trees has increased in it.

Mixed forests are a natural zone that is characteristic of a temperate climate. Broad-leaved and coniferous trees grow here at the same time, which is why the forest has such a name. Location of forests of this type on the planet:

North America - north of the USA, south of Canada;
Eurasia - in the Carpathians, in the south of Scandinavia, in the Far East, in Siberia, in the Caucasus, the sulfur part of the Japanese islands;
South America;
New Zealand is part of the islands.

To the north of the coniferous-deciduous forests is the taiga. In the south, the mixed forest turns into broad-leaved forests or forest-steppe.

Climatic conditions

The natural zone of mixed forests is characterized by a pronounced change of seasons. The world of flora and fauna here is adapted to both frost and heat. The average winter temperature is -16 degrees Celsius, and this figure can drop to -30 degrees. The cold season has an average duration. Summer in this zone is warm, the average temperature varies from +16 to +24 degrees. During the year, not much precipitation falls here, about 500-700 millimeters.

Types of flora

The main forest-forming species of mixed forests:

maple;
pine;

In the forests there are willows and mountain ash, alder and birch. deciduous trees shed leaves in autumn. Coniferous trees stay green all year round. The only exception is larch.

In mixed European forests, in addition to the main forest-forming species, elm, linden, ash, and apple trees grow. Among the shrubs there is viburnum and honeysuckle, hazel and warty euonymus. In the Caucasus, in addition to the listed species, beech and fir still grow.

The Far East is characterized by Ayan spruce and Mongolian oak, whole-leaved fir and Manchurian ash, Amur velvet and other plant species. In southeast Asia, there are yew, larch, birch, hemlock, as well as undergrowth - lilac bushes, jasmine and rhododendron.

North America is rich in the following types of plants:

sequoia;
sugar maple;
weymouth pine;
balsam fir;
yellow pine;
western hemlock;
bicolor oak.

Mixed forests are a very interesting natural area, which is represented by a huge biodiversity. Forests of this type are common on almost all continents and on some islands in the temperate zone. Some plant species are found in all mixed forests, while others are specific to certain ecosystems.

Mixed forests together with taiga and deciduous forests make up forest zone. The forest stand of a mixed forest is formed by trees of various species. Within the temperate zone, several types of mixed forests are distinguished: coniferous-deciduous forest; secondary small-leaved forest with an admixture of coniferous or broad-leaved trees and a mixed forest consisting of evergreen and deciduous tree species. In the subtropics, in mixed forests, mainly laurel and coniferous trees grow.

In Eurasia, the zone of coniferous-deciduous forests is distributed south of the taiga zone. Fairly wide in the west, it gradually narrows towards the east. Small areas of mixed forests are found in Kamchatka and the south of the Far East. In North America, such forests occupy vast areas in the eastern part of the temperate climate zone, in the Great Lakes region. In the Southern Hemisphere, mixed forests grow in New Zealand and Tasmania. The zone of mixed forests is characterized by a climate with cold snowy winters and warm summer. Winter temperatures in areas of the maritime temperate climate are positive, and as they move away from the oceans, they drop to -10 ° C. The amount of precipitation (400-1000 mm per year) slightly exceeds evaporation.

Coniferous-broad-leaved (and in continental regions - coniferous-small-leaved) forests grow mainly on gray forest and soddy-podzolic soils. The humus horizon of soddy-podzolic soils, located between the forest litter (3-5 cm) and the podzolic horizon, is about 20 cm. The forest litter of mixed forests consists of many herbs. Dying and rotting, they constantly increase the humus horizon.

Mixed forests are distinguished by a clearly visible layering, that is, a change in the composition of vegetation along the height. The upper tree layer is occupied by tall pines and spruces, and oaks, lindens, maples, birches, and elms grow below. Shrubs, herbs, mosses and lichens grow under the shrub layer formed by raspberries, viburnum, wild rose, hawthorn.

Coniferous-small-leaved forests, consisting of birch, aspen, alder, are intermediate forests in the process of coniferous forest formation.

Polissya - lowered treeless plains, composed of sandy deposits of melted glacial waters, are common in eastern Poland, in Polesie, in the Meshcherskaya lowland and are often swampy.

In the south of the Far East of Russia, where seasonal winds - monsoons - dominate within the temperate climatic zone, mixed and broad-leaved forests, called the Ussuri taiga, grow on brown forest soils. They are characterized by a more complex longline structure, a huge variety of plant and animal species.

In the mixed forests of North America, white and red pine are often found among coniferous trees, and birch, sugar maple, American ash, linden, beech, and elm are often found among deciduous trees.