Coniferous-deciduous (mixed) forests of the Russian Plain. Climatic features

The broad-leaved forest zone is located in Manchuria, the Far East, Europe, eastern China, and North America. It also affects the southern part of South America and parts of Central Asia.

Broad-leaved forests are most common where the climate is moderately warm and the ratio of moisture and heat is optimal. All this provides favorable conditions during the growing season. The leaf blades of the trees growing there are wide, hence the name of these forests. What other features does this natural area have? Broadleaf forests are home to numerous animals, reptiles, birds and insects.

Character traits

The peculiarity of broad-leaved forests is that they can be divided into two distinct tiers. One of them is higher, the other is lower. These forests are shrubby, the existing grasses grow in three tiers, and the ground cover is represented by lichens and mosses.

Another characteristic feature is the light mode. In such forests, two light maxima are distinguished. The first is observed in the spring, when the trees are not yet covered with leaves. The second is in the fall, when the foliage thins. In summer, light penetration is minimal. The above-described regime explains the peculiarity of the grass cover.

The soil of deciduous forests is rich in organo-mineral compounds. They appear as a result of the decomposition of plant litter. Trees in broadleaf forests contain ash. There is especially a lot of it in the leaves - about five percent. Ash, in turn, is rich in calcium (twenty percent of the total volume). It also contains potassium (about two percent) and silicon (up to three percent).

Trees of broadleaf forests

Forests of this type are characterized by a rich variety of tree species. The latter can be counted here about ten. Broad-leaved forests of the taiga, for example, are not so rich in this regard. The reason is that the conditions of the harsh taiga climate are not so conducive to the growth and development of flora. Many tree species that are demanding on soil composition and climate simply will not survive in unfavorable conditions.

In the southern part of the Tula region there is a famous forest area. It gives a great idea of ​​what broadleaf forests can be like. The soil of this area is favorable for the growth of trees such as small-leaved linden, Norway and field maples, common ash, elm, elm, wild apple and pear trees. Oaks and ash trees are the tallest, followed by Norway maples, elms and lindens. The lowest are field maples, wild pears and apple trees. As a rule, the dominant position is occupied by oak, and the remaining trees act as satellites.

Let us consider in more detail the above representatives of dendroflora.

Herbs

Plants of broad-leaved forests are characterized by large and wide leaf blades. For this reason they are called broad-grass oak forests. Some grasses grow in single specimens; they never form impenetrable thickets. Others, on the contrary, form a kind of carpet covering large spaces. Such herbs are dominant. Among them are common sedge, hairy sedge and yellow green grass.

Most of the herbaceous plants found in deciduous forests are perennial. They live up to several decades. As a rule, their existence is maintained through vegetative propagation. They reproduce poorly by seeds. A characteristic feature of these plants is long underground and above-ground shoots, rapidly growing in different directions and actively occupying new areas of the earth.

The above-ground parts of most representatives of oak groves die off in the autumn. Only the roots and rhizomes in the soil overwinter. They contain special buds, from which new shoots form in the spring.

An exception

Rare representatives of broad grass remain green both in winter and summer. Such plants include the following: hoofweed, green grass, hairy sedge.

Shrubs

As for these representatives of the flora, it is very difficult to find them in deciduous forests. They are simply not typical of oak forests, which cannot be said about coniferous forests, where shrubs grow everywhere. The most common are blueberries and lingonberries.

“Hasty” oak forest ephemeroids

These plants are of greatest interest to specialists studying forest flora. Among them are spring guillemot, various types of corydalis and goose onions. These plants are usually small in size, but they develop very quickly. Ephemeroids rush to be born immediately after the snow cover melts. Some especially fast sprouts make their way even through the snow. After a week, maximum two, their buds are already blooming. After a few more weeks, the fruits and seeds ripen. After this, the plants lie down on the ground, turn yellow, after which the part of them that is above the ground dies. Moreover, this process occurs at the very beginning of the summer period, when, as it may seem, the conditions for growth and development are as favorable as possible. The secret is simple. Ephemeroids have their own rhythm of life, which differs from the peculiar development schedule of other plants. They bloom lushly only in the spring, and summer for them is the time to wither.

The period most conducive to their development is early spring. At this time of year, the forest experiences maximum light as the bushes and trees have not yet acquired their thick green cover. In addition, during this period the soil is optimally saturated with moisture. As for high summer temperatures, ephemeroids do not need it at all. All these plants are perennial. They do not die after their aboveground part dries out. Living underground roots are represented by tubers, bulbs or rhizomes. These organs act as receptacles for nutrients, mainly starch. This is why stems, leaves and flowers appear so early and grow so quickly.

Ephemeroids are widespread plants in broad-leaved oak forests. There are about ten species in total. Their flowers are painted in bright purple, blue, and yellow colors. During flowering, ephemeroids form a thick, beautiful carpet.

Mosses

Broad-leaved forests of Russia are home to various types of mosses. Unlike taiga forests, in which these plants form a dense green soil cover, in oak forests mosses do not cover the soil so widely. The role of mosses in deciduous forests is rather modest. The main reason is the fact that leaf litter from broad-leaved forests has a detrimental effect on these plants.

Fauna

Animals of the broad-leaved forests of Russia are ungulates, predators, insectivores, rodents and bats. The greatest diversity is observed in those areas that are untouched by humans. Thus, in deciduous forests you can see roe deer, wild boars, fallow deer, sika and red deer, and elk. The order of predators is represented by foxes, wolves, martens, stoats and weasels. Broadleaf forests, where wildlife is rich and diverse, are home to beavers, squirrels, muskrats and nutria. In addition, these areas are inhabited by mice, rats, moles, hedgehogs, shrews, snakes, lizards and marsh turtles.

Birds of broad-leaved forests - larks, finches, warblers, tits, flycatchers, swallows, starlings. Crows, rooks, black grouse, woodpeckers, crossbills, jackdaws, and hazel grouse also live there. Birds of prey are represented by hawks, owls, owls, eagle owls and harriers. The marshes are home to waders, cranes, herons, gulls, ducks and geese.

In the past, broadleaf forests were inhabited by bison. Now, unfortunately, there are only a few dozen of them left. These animals are protected by law. They live in Belovezhskaya Pushcha (in the Republic of Belarus), in the Prioksko-Terrasny Nature Reserve (Russian Federation), in some Western European countries and in Poland. Several animals were transported to the Caucasus. There they coexist with bison.

The number of red deer has also undergone a change. They have become much smaller due to the barbaric actions of man. Massive plowing of fields has become disastrous for these beautiful animals. Deer can reach two and a half meters in length and three hundred and forty kilograms of weight. They tend to live in small herds of up to ten animals. In most cases, the female is dominant. Her offspring also live with her.

Sometimes in autumn, males gather a kind of harem. Resembling the sound of a trumpet, their roar spreads three to four kilometers around. The most successful deer, having defeated their rivals in fights, can gather up to twenty females around them. This is how another type of reindeer herd is formed. At the beginning of the summer season, deer give birth to their young. They are born weighing eight to eleven kilograms. Up to six months they experience intensive growth. One-year-old males acquire horns.

Deer feed on grass, leaves and shoots of trees, mushrooms, lichens, reeds, and wormwood. But pine needles are not suitable for food. In the wild, deer live for about fifteen years. In captivity, this figure doubles.

Beavers are another inhabitant of deciduous forests. The most favorable conditions for them are observed in Europe, North America, and Asia. The maximum recorded weight of this animal is thirty kilograms, and its body length is one meter. Beavers are distinguished by a massive body and a flattened tail. The membranes between the toes of the hind legs help to lead an aquatic lifestyle. Fur color can vary from light brown to black. By lubricating their fur with a special secretion, beavers protect themselves from getting wet. When immersed in water, the ears of this animal fold and the nostrils close. Economical consumption of air helps him stay under water for up to fifteen minutes.

Beavers prefer to settle on the banks of lakes and oxbow lakes, as well as slow-flowing rivers. They are attracted by abundant coastal and aquatic vegetation. It is a hole or a kind of hut, the entrance to which is located under the surface of the water. These animals build dams when the water level is unstable. Thanks to these structures, the flow is regulated, which allows water to enter the home. Gnawing branches and even large trees is easy for beavers. Thus, aspen trees of five to seven centimeters in diameter lend themselves to these animals in two minutes. Their favorite food is reed. In addition, they are not averse to eating iris, water lilies, and water lilies. Beavers live in families. The young go in search of a mate in the third year of life.

Wild pigs are another typical inhabitant of deciduous forests. They have a huge head and a very strong long snout. The most powerful weapon of these animals is sharp triangular fangs that are curved up and back. Boars' vision is not very good, but this is compensated by excellent hearing and a keen sense of smell. Large individuals reach a weight of three hundred kilograms. The body of this animal is protected by dark brown bristles. It is very durable.

Boars are excellent runners and swimmers. These animals can swim across a body of water that is several kilometers wide. The basis of their diet is plants, but we can say that wild boars are omnivores. Their favorite delicacy is acorns and beech nuts; they will not refuse frogs, mice, chicks, insects and snakes.

Representatives of reptiles

Broad-leaved forests are inhabited by snakes, vipers, copperheads, godwits, green and viviparous lizards. Only vipers pose a danger to humans. Many people mistakenly believe that copperheads are also poisonous, but this is not the case. The most numerous reptiles of deciduous forests are snakes.

Relief features

The zone of broad-leaved forests (and mixed) in the European part of Russia forms a kind of triangle, the base of which is located at the western borders of the country, and the top abuts the Ural Mountains. Since this territory was covered more than once by continental ice, its topography is mostly hilly. The most obvious traces of the presence of the Valdai Glacier are preserved in the north-west. There, the zone of broad-leaved and mixed forests is characterized by chaotic piles of hills, steep ridges, closed lakes and basins. The southern part of the described territory is represented by secondary moraine plains, which were formed as a result of a decrease in the inclined surface of hilly areas. The relief is characterized by the presence of sandy plains of varying sizes. Their origin is water-glacial. They are undulating, and sometimes you can find pronounced sand dunes.

Russian Plain

This zone is located in the temperate climate zone. The climate there is relatively mild and humid. The soil of these areas is soddy-podzolic. The close location of the Atlantic Ocean determined the relief features. The river network in coniferous-deciduous forests is well developed. Reservoirs have a large area.

The activity of the waterlogging process is determined by the proximity of groundwater and the humid climate. The plants that dominate the grass cover have wide leaf blades.

Conclusion

Broad-leaved forests located in Europe are classified as endangered ecosystems. But just two or three centuries ago they were one of the most diverse on the planet and were located throughout most of Europe. Thus, in the sixteenth to eighteenth centuries they occupied an area equal to several million hectares. Today there are no more than one hundred thousand hectares.

At the beginning of the twentieth century, only fragments of what was once a vast broadleaf belt remained intact. At the dawn of this century, attempts were made to grow oak trees in deserted territories. However, this turned out to be quite a difficult matter: the death of young oak groves was caused by constant droughts. At that time, research was carried out, led by the famous Russian geographer Dokuchaev. As a result, it was established that the failure to grow new trees was due to large-scale deforestation, since this forever changed the hydrology and climate of the area.

Today, secondary forests and artificial plantings grow in areas previously occupied by broad-leaved forests. They are dominated by coniferous trees. Unfortunately, as experts note, the dynamics and structure of natural oak forests cannot be restored.

Most of the Canadian Arctic Islands and Greenland.

Climate. Arctic. Negative or near-zero temperatures predominate.

Soils. Poor, rocky and swampy.

Vegetation. Mainly mosses and lichens.

Animal world. Muskox.

The northern coast of the mainland with adjacent islands. In the east are the coast of Hudson Bay and the northern part of the Labrador Peninsula.

Climate. Predominantly subarctic (partially arctic).

Soils. Tundra - gley, with excess moisture.

Vegetation. In the northern part there are mosses and lichens; in the southern part - marsh grasses, blueberries and blueberries, wild rosemary bushes, low-growing willows, birches, and alders. Woody vegetation appears to the south.

Animal world. Polar wolf, caribou reindeer, arctic fox, ptarmigan and some others. A variety of migratory birds. In coastal waters there are seals and walruses. On the northern coast there is a polar bear.

It stretches in a wide strip from east to west. Difficult coniferous forests.

Climate. Moderate (with increased moisture).

Soils. Podzolics predominate.

Vegetation. Mainly coniferous trees - balsam fir, black spruce, pine, sequoias, American larch. Hardwoods - paper birch, aspen. On the slopes of the Cordillera there are Sitka spruce and Douglas fir.

Animal world. Wolves, bears, deer and elk, foxes, lynxes, sables, beavers, muskrats. In mountain forests there are skunks, grizzly bears, and raccoons. In the rivers there are salmon fish. There are seal rookeries on the islands.

Mixed and broad-leaved forests

South of the tundra zone. (Variable moist forests predominate in the eastern part of the North American continent.)

Climate. Temperate, turning into subtropical.

Soils. Gray forest, brown forest, yellow soil and red soil.

Vegetation. In mixed forests - sugar maple, yellow birch, white and red pine, linden, beech. In the broad-leaved forests there are different types of oaks, plane trees, chestnuts, and tulip trees.

Animal world. Wapiti deer, bears (grizzly), moose, lynx, wolves, wolverines, raccoons, hares, foxes.

Evergreen tropical forests

In the south of the Atlantic and Mississippian and lowlands.

Climate. Subtropical.

Soils. Gray - brown, brown.

Vegetation. Oaks, magnolias, beeches, dwarf palms. The trees are entwined with vines.

Animal world. Diverse.

Forest-steppe

Treeless plains to the west of the forest zone. (In North America they are called prairies).

Climate. Subtropical.

Soils. Chernozems: podzolized and leached. Chestnut, forest gray.

Vegetation. Tall perennial grasses: wheatgrass, feather grass, etc. In river valleys there is woody vegetation. Near the Cordillera there are low cereal grasses (Gram grass and buffalo grass).

Animal world. Diverse and rich.

Desert and semi-desert zone

A significant part of the California coast, the Mexican highlands and the interior plateaus of the Cordillera.

Climate. Moderate (arid).

Soils. Brown and gray desert.

Vegetation. Black wormwood; on salt licks - quinoa solyanka; thorny bushes, cacti.

Animal world. Scarce.

Savannas and evergreen forests

On the slopes of the Caribbean and Central America.

Climate. There is a distinct change between dry and wet seasons.

Soils. Black, red-brown, brown, gray-brown

Vegetation. Tropical types of hard-leaved grasses. Trees with a long root system and umbrella-shaped crowns predominate.

Animal world. Versatile.

Climate zones

North America experiences almost every type of climate known on Earth. The natural change in temperature and circulation conditions from north to south determines the identification of different climatic zones on the continent.

The Arctic belt occupies the northern coast of the continent and most of the Canadian Arctic Archipelago. Cold and dry arctic air dominates here throughout the year. Therefore, even in summer, the air temperature, as a rule, does not rise above +5 °C. In winter, frosts reach –40 °C, and in Greenland –70 °C. There is little precipitation here and mostly in solid form. Low temperatures contribute to the formation of stable snow cover and glaciation.

The subarctic belt is located south of the Arctic (up to 58–60° N latitude). In summer, the climate of the territory is formed by moderate air masses. The air temperature during the warm period averages + 10 °C. In winter, when Arctic air dominates, it is even colder in the central part of the belt than in the Arctic zone. This phenomenon is explained by the remoteness of the territory from the ocean. There is more precipitation in the western part of the belt than in the eastern part.

Most of the continent lies in the temperate zone. The significant extension of the belt from north to south (more than 2000 km) determined large differences in surface heating. Within the belt, the amount of precipitation also varies significantly. The difference in moisture allowed us to distinguish three climatic regions here: marine, temperate continental and continental climate types.

The region of marine type climate covers the Pacific coast and the western slopes of the Cordillera. The temperature here varies little throughout the year. Relatively warm winters and cool summers are accompanied by heavy rains. There is 2000–3000 mm of precipitation per year.

On the contrary, the region of continental climate, which occupies the central part of the belt, is characterized by seasonal differences. Truly warm summers (with temperatures from +18 °C in the north to +24 °C in the south) give way to cold winters (with frosts from –20 °C in the north to –6 °C in the south). Precipitation falls significantly less than on the Pacific coast - 400–600 mm per year.

The region of temperate continental climate is located in the eastern part of the temperate zone. Although the winter here is cold, the summer is not so hot. In comparison with the continental climate area, the amount of precipitation also increases - on average up to 1000 mm.

The southern part of the continent lies in the subtropical zone, where winter is just a cool season: the temperature rarely drops below 0 ° C, and snow is a rare occurrence. In winter, cyclones of the polar front dominate here, carrying moist, moderate air masses. In summer they give way to dry tropical air masses. The precipitation regime and amount of precipitation are associated with the identification of three climatic regions in the subtropical zone: Mediterranean, subtropical continental and subtropical monsoon climate types.

The tropical zone occupies a small, narrow part of the continent lying between the Gulf of Mexico and the Pacific Ocean. Throughout the year, hot tropical air dominates here. It is thanks to this that the climate of the zone is figuratively called the “climate of eternal summer”, since it is difficult to distinguish warm and cold seasons here. However, moisture conditions within the belt are different. In this regard, two climatic regions are distinguished. The Mexican Highlands and the California Peninsula are in the desert tropical climate. There is very little rainfall here. This is caused by two reasons: a high pressure area in the North Pacific Ocean and the cold California Current. The eastern coast of the Gulf of Mexico and the islands of the West Indies lie in a humid climate region. This is explained by the year-round dominance of humid southeastern trade winds.

The tropical latitudes of North America in summer and autumn are subject to the action of powerful tropical cyclones - hurricanes. A squall wind with a speed of more than 100 m/s drives a wall of rain and raises fifteen-meter waves. The energy released by one hurricane could last a country like the United States for 600 years. It is not surprising that tropical cyclones are a constant scourge of coasts and islands. Nowadays, the weather service can predict hurricanes quite accurately, but at times they still cause catastrophic destruction.

The subequatorial belt covers the southernmost, narrowest part of the continent. High temperatures (above +25 °C) remain here throughout the year and experience almost no seasonal fluctuations. Precipitation falls mainly in summer, when moist equatorial air masses arrive here.

Conclusions:

North America is located in all but the equatorial climate zones.

In the temperate, subtropical and tropical zones, climatic regions are distinguished due to different amounts and patterns of precipitation.

25. physical-geographical zoning of North America

The diversity of the natural conditions of the continent allows, first of all, to distinguish two large regions based on differences in geological structure and topography: the Plain East and the Cordillera. At the second stage of zoning, taking into account landscape-climatic zonality and altitudinal characteristics, several natural areas are identified in each of these regions. The East includes the Canadian Arctic Archipelago and Greenland, the Canadian Plains, the Central Plains, the Great Plains, the Appalachians, and the Coastal Lowlands. The Cordillera mountain belt is divided into the following natural areas: the Alaskan Cordillera, the Canadian Cordillera, the Southern Cordillera (USA Cordillera), and the Mexican Highlands. The continental territory located in tropical latitudes - Central America - is considered as a special natural area. It includes a narrow strip of land and islands of the Caribbean Sea.

As an example of a natural area, it is better to consider the plains of Canada. They are in many ways reminiscent of the landscapes of the subarctic and temperate zones of Russia. This vast natural area lies within the Canadian Shield of the North American Plate. The relief is dominated by elevated plains (Laurentine Upland). In the north they turn into flat lowlands, and in the east into the plateaus of the Labrador Peninsula. The relief of the region was formed under the influence of Quaternary glaciation. Therefore, the area is characterized by an alternation of hilly ridges and interridge basins filled with lakes. The crystalline rocks of the Canadian Shield are associated with rich mineral deposits: iron, nickel, copper, platinum, lead, zinc, uranium, and gold. Deposits of oil, natural gas and coal are associated with sedimentary rocks of the marginal foothill trough of the Cordillera.

The climate on the plains of Canada is continental, subarctic and temperate. Winters here are long, cold and snowy. Summer in the north is short and cool, in the south it is warmer and longer. The region is rich in inland waters: many lakes and deep rapids rivers. There are significant reserves of hydropower resources.

The northern part of the plains of Canada is occupied by tundra and forest-tundra zones, turning into coniferous forests. In the southeast of the region there is a zone of mixed forests. Forest and fur are the main natural resources of the taiga.

In the north of the region, the population, mainly Indians, is engaged in hunting, logging, and working in mines and mines. Most of the region's population is concentrated in the southern plains, on the border of Canada and the United States. These are descendants of immigrants from Europe, mainly from France and England. There are large cities with many industrial enterprises here. These are ferrous and non-ferrous metallurgy plants, engineering, chemical, woodworking and pulp and paper mills. Significant areas of land in the south of the plains are plowed and sown with wheat, barley, and forage grasses. Part of the land is used for pastures. On the Atlantic coast the population is engaged in fishing.

A mixed forest is an area in which deciduous and coniferous trees coexist harmoniously. If the admixture of tree species is more than 5% of the total flora, we can already talk about a mixed type of forest.

The mixed forest forms a zone of coniferous-deciduous forests, and this is a whole natural zone characteristic of forests in the temperate zone. There are also coniferous-small-leaved forests that form in the taiga as a result of the restoration of previously cut down pines or spruces, which begin to displace different types of birch and aspen.

Main characteristics

(Typical mixed forest)

Mixed forests almost always coexist with broad-leaved forests in the south. In the northern hemisphere they also border the taiga.

The following types of mixed forests in the temperate zone are distinguished:

• coniferous-deciduous;
• secondary small-leaved with the addition of coniferous and broad-leaved species;
• mixed, which is a combination of deciduous and evergreen species.

Subtropical mixed foxes are distinguished by a combination of laurel leaves and conifers. Any mixed forest is distinguished by a pronounced layering, as well as the presence of areas without forest: the so-called opoles and woodlands.

Location of zones

Mixed forests, a combination of coniferous and broad-leaved species, are found on the East European and West Siberian plains, as well as in the Carpathians, the Caucasus and the Far East.

In general, both mixed and broad-leaved forests do not occupy as large a share of the forest territory of the Russian Federation as coniferous taigas. The fact is that such ecosystems do not take root in Siberia. They are traditional only for the European and Far Eastern regions and at the same time grow in broken lines. Pure mixed forests are found south of the taiga, as well as beyond the Urals to the Amur region.

Climate

Mixed-type forest plantations are characterized by cold, but not very long winters and hot summers. Climatic conditions are such that precipitation falls no more than 700 mm per year. The moisture coefficient is increased, but can change throughout the summer. In our country, mixed forests stand on soddy-podzolic soil, and in the west - on brown forest soil. As a rule, winter temperatures do not fall below - 10˚C.

Broad-leaved forest plantations are characterized by a humid and moderately humid climate, where precipitation is distributed evenly throughout the year. The temperatures are quite high, and even in January it never gets colder than -8˚C. Increased humidity and abundant heat stimulate the work of bacteria and fungal organisms, due to which the leaves quickly decompose and the soil maintains maximum fertility.

Features of the plant world

The peculiarities of biochemical and biological processes determine the consolidation of species diversity as we move towards broad-leaved species. European mixed forests are distinguished by the obligatory presence of pine, spruce, maple, oak, linden, ash, elm, and among the shrubs the leaders are viburnum, hazel, and honeysuckle. Ferns are very common as herbs. Caucasian mixed forests contain large quantities of beech and fir, while the Far Eastern forests contain birch, walnut, hornbeam, and larch. These same forests are distinguished by a variety of vines.

Representatives of fauna

Mixed forests are home to those animals and birds that are generally considered typical for forest conditions. These are moose, foxes, wolves, bears, wild boars, hedgehogs, hares, badgers. If we talk about individual broad-leaved forests, the species diversity of birds, rodents and ungulates is especially striking here. Roe deer, fallow deer, deer, beavers, muskrats and nutria are found in such forests.

Economic activity

The temperate natural zone, including mixed forests, has long been developed by local residents and is densely populated. An impressive part of the forest plantations was cut down several centuries ago, which is why the composition of the forest has changed and the proportion of small-leaved species has increased. In place of many forests, agricultural areas and settlements appeared.

Broad-leaved forests can generally be considered rare forest ecosystems. After the 17th century, they were cut down on a large scale, largely because wood was needed for the sailing fleet. Also, broad-leaved forests were actively cut down for arable land and meadows. Oak plantations have suffered especially badly from such human activity, and it is unlikely that they will ever be restored.

Arctic desert zone. This zone includes Franz Josef Land, Novaya Zemlya, Severnaya Zemlya, and the New Siberian Islands. The zone is characterized by a huge amount of ice and snow in all seasons of the year. They are the main element of the landscape.

Arctic air prevails here all year round, the annual radiation balance is less than 400 mJ/m2, and average July temperatures are 4-2°C. The relative humidity is very high - 85%. Precipitation amounts to 400-200 mm, almost all of which falls in solid form, which contributes to the formation of ice sheets and glaciers. However, in some places the supply of moisture in the air is small and therefore, when the temperature rises and strong winds, a large lack of moisture occurs and strong evaporation of snow occurs.

The soil-forming process in the Arctic occurs in a thin active layer and is at the initial stage of development. In the valleys of rivers and streams and on sea terraces, two types of soils are formed - typical polar desert soils on polygonal drained plains and polar desert solonchak soils on saline coastal areas. They are characterized by a low humus content (up to 1.5%), weakly expressed genetic horizons and very low thickness. In the Arctic deserts there are almost no swamps, few lakes, and salt spots form on the soil surface in dry weather with strong winds.

The vegetation cover is extremely sparse and spotty, characterized by a poor species composition and extremely low productivity. Low-organized plants dominate: lichens, mosses, algae. The annual growth of mosses and lichens does not exceed 1-2 mm. Plants are extremely selective in their distribution. More or less closed groups of plants exist only in places sheltered from cold winds, on fine earth, where the thickness of the active layer is greater.

The main background of the Arctic deserts is formed by crustose lichens. Hypnum mosses are common; sphagnum mosses appear only in the south of the zone in very limited quantities. Higher plants include saxifrage, arctic poppy, semolina, chickweed, arctic pike, bluegrass and some others. The grasses grow luxuriantly, forming hemispherical cushions up to 10 cm in diameter on a fertilized substrate near the nesting areas of gulls and lemming burrows. Ice buttercup and polar willow grow near patches of snow, reaching only 3-5 cm in height. The fauna, like the flora, is poor in species; There are lemmings, arctic foxes, reindeer, polar bears, and the most common birds are the ptarmigan and the polar owl. On the rocky shores there are numerous bird colonies - massive nesting grounds for seabirds (guillemots, little auks, white gulls, fulmars, eiders, etc.). The southern shores of Franz Josef Land and the western shores of Novaya Zemlya are a continuous bird market.

Remember within which natural zones Ukraine lies. What types of trees are common in the forests of Ukraine?

GEOGRAPHICAL POSITION. Forests in the northern and western parts of Ukraine occupy 28% of the territory. The zone of mixed forests (coniferous-deciduous), which is called Polesie, stretches from west to east in a wide strip between the northern border of Ukraine and a conditional line passing through the cities of Vladimir-Volynsky - Lutsk - Rivne - Zhitomir - Kyiv - Nizhyn - Glukhov. Polesie is an amazing land of forests and rivers, where there are no crushing droughts, where in some villages in the spring they move along the streets on boats, where the air smells of pine and hops, and it seems that you can drink it like birch sap.

This is how the field pikes poetically describe their region.

In the west of Ukraine, mixed forests are replaced in the south by broad-leaved forests, which extend to the Cis-Carpathian Upland and the border with Moldova.

RELIEF AND MINERAL RESOURCES. The mixed forest zone occupies mainly the Polesie lowland (Fig. 138). Its surface is almost flat, with a slight slope towards the Dnieper and Pripyat. Its absolute heights rarely exceed 200 m; the highest section is the Slovechansko-Ovruch Ridge (more than 300 m). The relief was affected by the influence of the glacier: it brought polished stones and boulders from the north, leaving sediments in the form of sandy fields, moraine hills and ramparts (Volyn ridge). Wind-blown sands form dunes up to 5 km long and up to 18 m high.

Broad-leaved forests cover the hills - Volyn, Rastochye, Podolsk (western part), Khotyn. The hills underwent tectonic uplift at the end of the Cenozoic era, which resulted in the incision of river valleys and the spread of water-erosive landforms.

As a result, the terrain in many places has become hilly, with heights often exceeding 400 m above sea level. At the same time, in the watershed areas of the Podolsk Upland there are flat hills - plateaus (Fig. 139). The Podolsk Upland and the Prut-Dniester interfluve are the largest accumulation of karst landforms in Ukraine. There are more than 100 caves in gypsum deposits. Among them are the longest in the world - Optimisticheskaya (more than 240 km), Ozernaya, Zolushka, as well as Kristallicheskaya, Mlynki, etc.

In places of shallow occurrence of crystalline rocks, deposits of copper (Volyn region), kaolin, granites, basalts, labradorites, gabbro and semi-precious stones - topaz, jasper, amber (Rivne, Zhytomyr regions), phosphorites (Sumy, Khmelnytsky regions) were found. Everywhere in Polesie there are deposits of peat, and in Podolia - limestone. The Lviv-Volyn coal basin is located on the border with Poland.

CLIMATE AND INTERNAL WATERS. The climate of forest zones is moderate continental. The air temperature varies from west to east in January from -4 to -8 °C, in July - from + 17 to +19 °C. In forest zones there is more precipitation compared to the flat areas of Ukraine (600-700 mm per year).

With low evaporation, moisture in the mixed forest zone is excessive. Therefore, a characteristic feature of Polesie is swampiness. Among the swamps, lowland ones prevail, lying along rivers. In the central-eastern part, the zone is crossed by the Dnieper, receiving the tributaries Pripyat, Desna, Teterev, Irpen. Their river systems form a dense network of rivers. Pripyat originates in the north-west of the Volyn region and is located only in the upper and lower reaches in Ukraine. Its numerous branches, straits and old channels are filled with water in the spring and form a continuous body of water. Large tributaries of the Pripyat are Turia, Stokhod, Styr, Uzh, Goryn (with the tributary Sluch). All rivers have wide valleys with low banks and a slow flow. They are deep-water, as they feed mainly on precipitation.

At the extreme

in the west, the Western Bug has similar characteristics. In the south, the zone of broad-leaved forests is outlined by the Dniester; its left tributaries, crossing the Podolsk Upland, form deep, often canyon-like valleys in the lower reaches.

There are many lakes in Polesie. These are mainly small bodies of water with clean running water. In the northwestern part of the zone there are Shatsk lakes (Svityaz, Pulemetskoe, Luka, Pesochnoe, etc.), mainly of karst origin. Small oxbow lakes are common along the rivers. On the Podolsk Upland there are small karst lakes - “windows”.

SOIL-VEGETATION COVER AND LANDSCAPE. In the natural zoning of Ukraine, the zone of mixed forests is identified as the Polesie physical-geographical region (Ukrainian Polesie), and the zone of broad-leaved forests is designated as the Western Ukrainian region.

In the Polesie physical-geographical region, mixed forests are dominated by soddy-podzolic soils. Their fertility is low due to high acidity and excess moisture. Even less fertile are the soils formed in river valleys and lower reaches - meadows, swamps, peat bogs and peat bogs. Compared to other landscapes of the flat part of Ukraine, the vegetation of Polesie (forest, meadow and swamp) is better preserved, but the name “Polesie” itself rather reflects its natural history than its current state. Forests once covered 90% of the territory, but now they occupy only 25%. Another 10% of the area is meadows.

Swamps characteristic of Polesie occupy more than 4% of its territory. In total, more than 1,500 plant species are known in Polesie.

Of the forest communities, the majority are pine-oak forests. The undergrowth in them is formed by hazel, elderberry, willow, euonymus, and numerous herbaceous plants. Sparse pine forests (pine forests) grow on sandy areas.

There are almost no shrubs or grasses in them; low areas are completely covered with moss. Wet areas are occupied mainly by alder and birch forests. Meadows in Polesie are common not only in floodplains, but also in places where forests have been cut down. The greatest diversity of herbaceous plants is in floodplain meadows. They meet here and there

sands covered with thyme or heather. Lowland swamps are famous for their variety of grasses (yellow killer whale, loosestrife, beaver grass, and swamp beetle). Raised bogs overgrown with moss, cranberries, and sundews are rare. Among the sandy lowlands of Polesie there are large swamps covered with hummocks of grass.

In the Western Ukrainian region, gray forest soils have formed under broad-leaved forests. As we move east, chernozems spread - typical, on which there was once rich meadow and steppe vegetation, and podzolized (formed in the process of natural overgrowing of steppe spaces with broad-leaved forests). Today, broad-leaved forests occupy less than 15% of the region's area. The predominant deciduous species are oak and beech (in the west), oak and hornbeam (in the east). Ash, maple, and linden are also common, with occasional stands of pine and spruce. Steppe vegetation has been preserved in small patches on hillsides or in ravines.

The forests are inhabited by roe deer, raccoon dog, wild boar, wolf, fox, marten, hare, and squirrel. Brown bear and lynx are occasionally seen. Beavers build their huts along the rivers. There are many birds - black grouse, wood grouse, crane, stork.

So, the physical and geographical diversity of forest zones of Ukraine forms the following natural landscapes: mixed-forest coniferous-deciduous lowland (Polessye), broad-leaved forest upland, floodplain meadow and meadow-swamp. Nowadays, most of the zone’s territory is occupied by anthropogenic landscapes.

NATURE MANAGEMENT AND NATURE CONSERVATION.

The zones of mixed and deciduous forests of Ukraine and the neighboring territories of Belarus and Poland are the ancestral home of the Slavs. From here they settled throughout Eastern Europe. For a long time, the forest zone was sparsely populated; natural forests were preserved almost untouched. Intensive destruction of forests due to human economic activity began in the 16th century. Subsequently, agricultural development of land and industrial logging intensified, cities arose, and roads were laid. Currently, agricultural landscapes cover more than 65% of the Polesie area and about 80% of deciduous forests. Enormous changes occurred in natural landscapes after the drainage of swamps and straightening of river beds.

In 1986, an accident occurred at the Chernobyl nuclear power plant on the territory of the forest zone. People were evicted from the 30-kilometer zone around it, as a result of which natural processes occur there without their participation, but under the influence of severe radiation pollution. Their progress is monitored in the Drevlyansky Nature Reserve and the Chernobyl Radiation-Ecological Biosphere Reserve, created in 2016. To preserve the landscapes of Polesie, forest and swamp vegetation in mixed forests, a number of conservation areas have been created. In particular, in the Cheremsky, Rivnensky and Polessky natural reserves, swamp-peat massifs, lakes, and pine forests are studied and protected. In the Shatsky National Natural Park there are 22 lakes under protection, in which valuable species of fish (eel, catfish) are found, and swamps located among pine forests and alder forests.

In the broad-leaved forests in the natural reserve "Raztochya" and the national natural park "Yavorovsky" forest areas of beech and oak are protected, and in the natural reserve "Medobory" and the national park "Podolskie Tovtry" - unique natural complexes of Tovtry.

REMEMBER

Mixed forests (Polesie) occupy the northern part of Ukraine, and broad-leaved forests occupy the western part.

The mixed forest zone is characterized by swampiness, glacial landforms, soddy-podzolic soils, pine-oak, pine and alder forests.

The broad-leaved forest zone is characterized by elevated terrain, gray forest soils and chernozems, oak-beech and oak-hornbeam forests.

QUESTIONS AND TASKS

1. Describe the geographical location of mixed and deciduous forest zones. Find out on the map which administrative regions of Ukraine are completely or partially located in these zones.

2. What are the differences in the topography of mixed and deciduous forest zones?

3. Why are there many swamps in Polesie and a dense river network formed?

4. Name the plant communities and representatives of the animal world of mixed and deciduous forests.

5. How is the natural environment protected and preserved in the forest zone?

This is textbook material