Forests of temperate latitudes. Temperate forests (temperate forests) Climate in the deciduous forest zone

Temperate forests are forests that grow in regions with a temperate climate, for example, East End North America, Western and Central Europe and Northeast Asia. Temperate forests are found at latitudes between approximately 25° and 50° in both hemispheres. They have a temperate climate and a growing season that lasts 140 to 200 days a year. Precipitation in temperate forests tends to be evenly distributed throughout the year. The temperate forest canopy is primarily composed of broadleaf trees. In the polar regions, temperate forests give way.

Temperate forests first appeared about 65 million years ago, during the beginning cenozoic era. At that time, global temperatures dropped and forests sprang up in more temperate regions above the equator. In these regions, the temperature was not only cooler, but also showed seasonal fluctuations. Plants evolved and adapted to climate change.

Today, in temperate forests that are closer to the tropics (where the climate has not changed as much), trees and other plant species more closely resemble vegetation from. Temperate evergreen forests can be found in these regions. In areas where climate change has been more intense, deciduous trees have evolved (they shed their leaves each year when the weather turns cold as an adaptation, allowing the trees to withstand seasonal temperature fluctuations in these regions).

Main characteristics of temperate forests

The following are the main characteristics of temperate forests:

grow in temperate regions (at latitudes between about 25°-50° in both hemispheres);
experiences distinct seasons, with a growing season that lasts 140 to 200 days;
the forest canopy consists mainly of deciduous trees.

Classification of temperate forests

Temperate forests are divided into the following habitats:

Temperate deciduous forests - grow in eastern North America, Central Europe and parts of Asia. They are characterized by temperature fluctuations from -30° to +30° C throughout the year. They receive about 750-1500 mm of precipitation per year. Broadleaf forest vegetation includes a variety of broadleaf tree species (eg oak, beech, maple, hickory, etc.) as well as various shrubs, perennial grasses, mosses and fungi. Temperate deciduous forests are found in mid-latitudes, between the polar regions and the tropics.
Temperate evergreen forests - consist mainly of evergreen trees that renew their foliage throughout the year. Temperate evergreen forests are found in eastern North America and the basin mediterranean sea. They also include subtropical broadleaf evergreen forests in the Southeastern United States, southern China, and eastern Brazil.

Some of the animals that inhabit temperate forests include:

The Eastern Chipmunk (Tamias striatus) is a species of chipmunk that lives in the deciduous forests of eastern North America. Oriental chipmunks are small rodents with red-brown fur adorned with dark, light and brown stripes that run along the back of the animal.
The white-tailed deer (Odocoileus virginianus) is a species of deer that inhabits deciduous forests in eastern North America. White-tailed deer have a brown coat and a tail that is white on the back.
The American black bear (Ursus americanus) is one of three species of bears that live in North America, the other two and . Of these species, black bears are the smallest and timid.
Robin (Erithacus rebecula) is a small bird from the flycatcher family (muscicapidae). The robin's habitat range is quite extensive and includes: Northwest Africa from Morocco to eastern Tunisia and the Mediterranean coast, as well as most of the Eurasian continent.

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compact array of trees and shrubs. More than a third of the land surface is covered with forests or suitable for their development. However, the areas occupied by forests are unevenly distributed between the continents and even within each of them. For example, forest cover covers almost half South America, about a third of Europe and the US and a large part of Africa and Asia; in Australia, on the contrary, there are few of them, and some major countries, such as Egypt, are generally treeless. Forests are completely absent in Antarctica and Greenland, but low trees grow in the extreme south of the latter.

Although most feature forests the presence of trees and shrubs, it is not just woody vegetation, but a complex community (or ecosystem) consisting of closely related elements. Like all ecosystems, the forest is formed by a combination of living organisms (biota) and the inanimate (abiotic) environment of their habitat. The forest biota includes, in addition to trees and shrubs, other plants (grasses, mosses, fungi, algae, and lichens), as well as vertebrates and invertebrates, and bacteria. The abiotic component is represented by air, soil and water. All these components are alive and inanimate nature are closely interconnected due to the passage of energy flow through the ecosystem and the circulation of oxygen and other substances in it. For example, the energy of sunlight is used by plants for photosynthesis the process of formation of organic nutrients from the water and carbon dioxide. Since this is characteristic only of green plants, all animals must eat either these plants or other animals, which in turn eat plants. Thus, plants directly or indirectly provide food for all other organisms. As a by-product of photosynthesis, oxygen is released into the air, replenishing its reserves in the atmosphere. Bacteria and other organisms involved in the decomposition of organic matter play a vital role in forest ecosystems. They turn complex chemical compounds, which make up metabolic wastes and the remains of plants and animals, into simple ones that can be reused by organisms ( see also ECOLOGY).

In most forests, several tiers are distinguished, formed by foliage of plants of different heights. The topmost, consisting of the crowns of the most tall trees, is called the first tier or forest canopy. In some areas, especially in the tropics, individual giant trees rise significantly above the canopy. If there are other relatively closed tree tiers under it, they are called the second, third, etc. Shrubs, tall grasses (in some types of forest) and stunted trees form the undergrowth. The herbaceous layer consists of subshrubs and grasses. Mosses, lichens and creeping plant species form a surface, or ground, layer.

Organic matter, consisting of fallen leaves, twigs, flowers, fruits, bark and other plant remains, as well as feces and animal carcasses, shells of pupae and larvae, etc., forms forest floor on the soil surface. In most forests, the litter is the most densely populated layer. Often in it for one square meter there are several million living organisms from protozoa and bacteria to mice and other small mammals.

The edge of the forest is a transitional strip between it and the adjacent type of vegetation. It is characteristic that, within the limits of the edge, the trees are covered with foliage almost to the very ground, and many shrubs and herbs common here are rare or not found at all in the forest and in neighboring open areas. plant communities. Some bird species, often thought of as forest birds, actually live mainly on forest edges, which are also an important habitat type for mammals.

Geography forest resources the globe . M., 1960
Forests of the USSR, tt. 15. M., 19661970
Walter G. Vegetation of the globe, tt. 13. M., 19691975
Bukshtynov A.D., Groshev B.I., Krylov G.V. The woods. M., 1981

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Deciduous forest in Germany

Deciduous forest in autumn, England

Deciduous forests - forests consisting of deciduous trees and shrubs. They are also called deciduous or summer green for the characteristic annual shedding of leaves before the onset of cold weather.

Deciduous forests in Europe account for 24%.

Spreading

The deciduous forest zone is better developed in the Northern Hemisphere and is located south of the zone boreal coniferous forests moderately cold climate, the southern border of which runs between 50 ° and 60 ° northern latitude, but does not cover the entire territory of the temperate zone proper. It includes Western Europe, Central Europe, Southern Scandinavia, wedges out in Eastern Europe to Southern Urals, a narrow strip runs in the latitudinal direction in the south Western Siberia and after a break - a wide meridional strip along the coast of East Asia from the Yangtze to 54 ° north latitude; there are isolated sections of this zone in the Caucasus and South Kamchatka.

In Europe, deciduous forests reach far to the north, in the western part of their range even north of 58 ° north latitude, which is associated with the favorable influence of the Gulf Stream. Deciduous forests in Europe extend along the Atlantic coast, from the northern part of the Iberian Peninsula to southern Scandinavia; in Eastern Europe, where the influence of the continental climate is felt, deciduous forests begin to wedge out already in the Dnieper region; thus, their distribution area on the European continent resembles a triangle in shape. In Western Europe, deciduous forests are represented by Atlantic heaths, as an extreme degree of degradation of deciduous forests, forests have survived in such a densely populated area as Central Europe, only in small limited areas, to the east they are replaced by mixed forests.

In North America, deciduous forests are developed on the east coast, where they stretch in a strip up to 1000 km from North Florida to 50 ° north latitude. Deciduous forests in North America and East Asia are limited from the south by subtropical wet forests Florida or East China, and from the north - boreal coniferous forests; mixed forests predominate in transitional zones.

In the Southern Hemisphere, deciduous forests are found in southern Central Chile and Tierra del Fuego. The southern border of deciduous forests in Chile runs in a longitudinal valley at 41 ° 30 "south latitude, in the coastal ridges - at 40 ° south latitude, on the western slope of the Andes - at 39 ° south latitude. These forests are also found on two high peaks of the Campana coast ridge and Robles, far to the north of the main zone, between 39° and 40° south latitude they pass into the Argentine side of the Andes.

Climate

The zone of distribution of deciduous forests is characterized by a temperate climate, with alternating summer, autumn, winter and spring periods. peninsular character Western Europe causes the influence of the ocean on the climate. The prevailing westerly winds bring moisture into the interior of the continent, and the prevailing warm ocean currents prevent the formation of ice off the coast of Western Europe south of the North Cape. In the western part of Europe, winter temperatures are 20° above the mean temperature for the corresponding latitude. The further inland the continent, the stronger the manifestations of the continental climate with cold winters and hot summers. The zero isotherm, which limits the frost-free climate, runs from the North Cape in Norway south to Hamburg and the Alps, crosses the Balkans and Crimea, and reaches the city of Baku on the Caspian Sea. The frost-free period lasts from 200-208 days in the west to 120 days in the east of the European part of the deciduous forest zone. average temperature in summer at 55° north latitude it is 21°C, while on the Mediterranean coast there are three hot months when the temperature exceeds 21°C. Annual rainfall in the mountains and part of the west coast exceeds 1500 mm per year. In the Pyrenees, the Alps, the Carpathians and the Caucasus, there are places where the annual rainfall is up to 1000-1200 mm per year. In most of Europe, the annual rainfall is between 500 and 1000 mm per year. The Far East of Russia is characterized by a mild climate, where the Pacific Ocean influences.

In North America, the climate varies from region to region due to big size continent. In the zone temperate climate summer periods hotter and winters colder than in Europe. Dominant northwest winds blowing with Pacific Ocean and create a mild and even climate on the west coast. In this and other coastal areas precipitation plentiful, less precipitation falls within the continent.

They occupy a much smaller area in the forest zone than the taiga. They grow in the west of the European part of Russia and in the south of the Far East.

In Siberia, mixed and broad-leaved forests are absent: there the taiga passes directly into the steppe.

More than 90% of mixed forests consist of coniferous and small-leaved species. This is mainly spruce and pine with an admixture of birch and aspen. broad-leaved species in mixed forests few. Broad-leaved forests consist mainly of oak, linden, maple, elm, in the southwestern regions - ash, hornbeam, beech. The same breeds, but local species are also represented on Far East, where, in addition, grow Manchurian walnut, grapes and creepers.

The northern boundary of the distribution of the zone lies approximately along 57 ° N. sh., above which the oak disappears, and the southern one adjoins the northern border of the forest-steppe, where the spruce disappears. This territory forms, as it were, a triangle with peaks in Leningrad, Sverdlovsk, and Kyiv.

Mixed and broad-leaved forests are located mainly on the East European Plain, which has a flat, low-lying surface interrupted by a number of uplands. Here are the sources, watersheds and pools largest rivers European part of Russia: Volga, Dnieper, Western Dvina. On floodplains, forests are interspersed with lush meadows, and on watersheds - plowed fields. Due to the proximity of groundwater and limited runoff, flat lowlands are heavily swamped in places (Polesie, Meshchera). In addition to forest swamps and lakes, in some areas there are sandy soils covered with pine. In forests on clearings and swamps, many berry bushes and herbs grow.

Compared to the taiga, the climate of mixed and deciduous forests is less severe. Winter is not so long and frosty, summer is warm. The average temperature in January is -10...-11°С, and in July +18...+19°С. The average annual rainfall is from 800 to 400 mm. In general, the climate is transitional from maritime to continental in the direction from west to east. If in the Baltic States and Belarus the proximity of the sea smooths out the difference between the air temperature in summer and winter, then in the Vyatka and Kama basins it becomes significant. In summer, the air here warms up to +40°С, and in winter frosts reach -45°С. In all seasons of the year, winds that carry moisture from the Atlantic Ocean prevail.

The snow cover is less thick than in the taiga, with a layer of 20-30 (in the west) to 80-90 cm (in the east). It lasts an average of 140-150 days a year, in southern regions- 30-60 days.

With the onset of winter, life in the forests, especially in broad-leaved ones, freezes. Most insectivorous birds fly away to warmer climes, and some of the animals flow into hibernation or sleep ( the bats, hedgehogs, dormouse, badgers, bears). In spring and summer, all tiers of forests are inhabited by various animals.

Broad-leaved, or summer-green, forests in the temperate latitudes of the Northern Hemisphere do not form a single zone and occupy disparate territories with a weakened continentality in Europe, Asia and North America. The climate in the area of forests of this type is moderately cool, precipitation is distributed relatively evenly throughout the year, and their amount varies over a fairly wide range. A break in the growing season due to winter cold is characteristic. Depending on the degree of continentality of the climate, winters can be almost frost-free (the Atlantic regions of Europe) or with persistent frosts with heavy snow cover.

The northern boundaries of the distribution of broad-leaved forests are determined by the duration of the cold period and (or) lack of summer heat. Late spring and early summer frosts, which are especially detrimental to undergrowth, apparently play a significant role in the advancement of individual species. On the southern borders, the main limiting factor is humidity, which determines the transition to the steppes. The replacement of broad-leaved forests by coniferous forests occurs very gradually; a strip of mixed coniferous-broad-deciduous forests stands out.

Vegetation. The forests are characterized by a closed upper tree layer, the lower tree layers are either very sparse or absent. Many broad-leaved species give root and stump shoots, coppice stands are shorter and more closed. There are mono-, oligo- and polydominant forests. Beech species tend to form monodominant stands. The shrub layer varies from well developed to extremely sparse.

Lianas are usually few, but in some regions (East Asia, southern part Atlantic forests of North America) they are very abundant. The herbaceous cover is formed by perennial species that are ecologically different. There is a group of mesophilic shade-loving herbs with a long growing season. Characteristic are plants that bloom in the spring, when a lot of light enters the forest canopy, and end their above-ground existence shortly after the leaves bloom on the trees. In the humid climate of the coastal regions, the herbaceous layer includes some evergreen species, the share of which decreases in the continental regions.

Broad-leaved forests have long been subjected to uprooting followed by plowing of the land, constant cutting, often accompanied by a directional change of species. Significant

areas formerly occupied by forests have been converted into agricultural land.

European broadleaf forests are floristically the poorest and structurally relatively simple. There are practically no primary forests. The main forest-formers are species of beech, oak; the role of chestnut, as well as hornbeam, ash and linden, is limited. In the eastern more continental regions and on the border with the steppe formations, only pedunculate oak forests spread.

The specificity of the forests of Asia is determined primarily by the amazing species richness of trees, shrubs and herbs, and a significant part of them belong to ancient genera. In comparison with European forests, the role of vines and epiphytic ferns is increased in them.

In North America, broad-leaved forests are distributed only in the eastern part of the continent. Striking species diversity and richness of the composition of trees, an abundance of shrubs, as well as lianas.

There is a certain similarity between the forests of East Asia and North America, which is enhanced by the preservation in them of a large number of representatives of the ancient deciduous flora. The presence of two or three tiers of forest stands is associated with a large variety of tree species. Dominant stands are species of oak, maple, plane tree, elm, ash, walnut, tulip tree, etc. The forests are preserved to the greatest extent in the foothill regions of the southwestern Appalachians and in river valleys.

Broad-leaved summergreen forests are extremely limited in the Southern Hemisphere. In conditions very humid climate evergreen deciduous forests prevail, structurally and floristically weakly delimited from subtropical forests, with an even annual temperature variation.

animal population. A well-defined layered structure of broad-leaved forests, the presence of a closed tree layer up to 30 m above the ground, abundant litter, and a thick humus horizon provide a full range of layers of the animal population of this biome.

warm, humid summers and Cold winter with snow cover determine a clear seasonal dynamics of animal activity. For the winter, poikilothermic animals fall into a state of suspended animation. Of the homoiothermic animals (birds and mammals), some migrate to warmer regions, others fall into hibernation or winter sleep, and only a few remain year-round activity, switching to specific food (bark and branches of trees, insects sleeping under the bark, etc.). )

The litter of trees and shrubs forms a thick layer of litter. Activities for the disposal of dead plant mass in deciduous forests carries out extensive and diverse group saprophage animals, among which the leading role is played by earthworms Lumbricidae family. Together with saprophages, the soil layer is inhabited by consumers of the living root mass of plants. These include insect larvae, mainly beetles: hard, densely covered larvae of click beetles, called wireworms, white fat larvae of lamellar beetles, living in the soil for several years before pupation. Of these, the larva of the May beetle is the most typical.

In the lower and middle parts of the forest stand, xylophagous insects - consumers of wood - settle in the trunks and branches of trees. These are larvae of longhorn beetles, lamellar (for example, large larvae of a stag beetle). The bark is eaten by the larvae of borers. In the crowns of deciduous trees, insects are abundant that eat the green tissues of the leaves. Caterpillars of various butterflies dominate among them: moths, silkworms, leafworms, larvae (false caterpillars) of sawflies, adult forms (adults) of leaf beetles, beetles, in particular, the already mentioned May beetles. special group phytophagous insects form sap-sucking species - aphids, mealybugs, cicadas, psyllids, cicadas, bugs.

There are also many phytophages among vertebrates. Small rodents live in the ground layer. In the Eurasian forests, this is a forest bank vole, forest and yellow-throated mice, in the deciduous forests of North America - outwardly similar to mice, white-legged and golden hamsters.

Large ungulates are involved in the consumption of green mass of foliage, grass, and in winter branch fodder and tree bark. In Eurasia and North America, the red deer is widespread, known in different parts area called deer, red deer, wapiti (the latter refers to the American red deer). In the Western European sector, the deer joins the deer, and in the Far East - dappled deer. Unlike deer, the wild boar feeds not only on the aboveground, but also on the underground parts of plants (rhizomes, tubers, bulbs), which he digs up, loosening the litter and topsoil with his nose. There he finds and eats all kinds of invertebrates.

Predatory animals - zoophages inhabit all tiers of deciduous forests. Predatory millipedes live in the soil-litter - geophiles and drupes, beetles (ground beetles and rove owls), spiders and predatory mites. Leading place among carnivores

invertebrates are occupied by ants, which build ground nests, but survey all forest tiers in search of food. The upper part of the soil is mastered in search of food by various moles. In the European forests, the common mole is numerous, in the forests of East Asia - the Moger mole.

In the terrestrial layer, amphibians and reptiles are common: brown frogs, newts and salamanders, especially diverse in the forests of North America, lizards and snakes.

Insectivorous birds gather food mainly in the crowns of trees and in the litter. Thrushes, flycatchers, tits, warblers and warblers are common in the forests of Eurasia. In American forests, thrushes and tits are also common, but the ecological niche of flycatchers is occupied by tyrants, and warblers and warblers are American warblers, or treeworts.

Predatory animals are characteristic of both ground and tree layers. In the terrestrial - predators live, widely settling outside the broad-leaved forests: fox, wolf, Brown bear(in the past), ermine and weasel. The black bear and the raccoon dog (now introduced into European forests) live in the Far East, and the baribal bear close to the black bear lives in North America. The tree layer is used by lynx, wild forest cat, pine marten constantly keeps there, in the Far East - charza.

Long-term and intensive agricultural development of the regions of broad-leaved forests has led to a sharp depletion of their animal population, to complete disappearance many species, especially large vertebrates. Grain-eating rodents multiplied strongly on arable lands. We can judge the primary population of animals in these communities from historical data and from the remains of natural biocenoses in the territories of reserves and in remote, poorly developed areas.

Biomass reserves in broad-leaved forests of temperate latitudes are very high - 500-400 t/ha. The production of deciduous forests is also high - from 10 to 30 and even 50 t/ha per year, which is explained by favorable warm and humid conditions of the growing season. The thickness of the soil and litter layers provides food for a huge number of soil animals. It is mainly due to them that the zoomass in these forests can reach 1 t/ha or even more, which exceeds the zoomass reserves in most other land biomes.