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Forest zone. forest zone

Forest classification

In our country, several classifications of forests have been developed according to their water protection and protective value. The most complete is the classification of IV Tyurin (1949), which is built on a zonal basis. Within the zones, it takes into account the terrain, soil conditions, the composition of the forest stand, and the types of water protection and protective role of the forest. All forests are divided into four classes according to the degree of fulfillment of their water protection role.

I class - forests with the highest degree of manifestation of water protection and protective properties.

1. Anti-erosion (bank and slope protection) and channel-protective forests: coast-protective thickets of willows and shrubs along the edge of the floodplain and along steep washed-out banks; slope-protective forests on high steep slopes (primary banks) of river valleys, dry valleys, gullies, ravines, ravines, at all degrees of afforestation of watersheds.

2. Soil-moisturizing forests: water-absorbing and clogging along the slopes and bottom of hollows with karst funnels; runoff intercepting along catchment troughs and across the fall of gentle slopes with a treeless overlying catchment area; pegs along the steppe depressions; spring forests (alder forests) along streams (brooks) in floodplains and meadow terraces.

3. Soil-protective (sand-reinforcing) forests: pine forests on dry sandy soils, and primarily in the steppe and forest-steppe zones; floodplain forests on the sands near the riverbed.

4. Shelter belts in the forest-steppe and steppe zones. In forests of class I, IV Tyurin (1949) distinguishes subclass 1a with the highest degree of water protection and protective properties. It includes bank-protective willow forests, forests along high steep slopes, water-absorbing forests along hollows with sinkholes, aspen groves along steppe depressions, and sand-reinforcing forests.

Class II - forests characterized by a high degree of manifestation of the water protection and protective role.

1. Anti-erosion forests: on sloping slopes along all links of the hydrographic network, with the exception of areas belonging to class I, and forests on sloping slopes of hills remote from river valleys; floodplain on loamy soils with low forest cover on the slopes of the catchment area.

2. Moisture forests: on the lower parts of gentle slopes with non-forested overlying parts of the slope; on flat terraces in the part adjacent to unforested overlying slopes; separate small plots or strips of forest on gentle slopes, wide terraces and watershed plateaus occupied by field or meadow lands.

3. Soil-protective (sand-reinforcing) forests: pine forests on dry sandy soils with hilly terrain in the northern half of the forest-steppe zone, in the zone of mixed and partially coniferous forests; forests on sandy drifts in floodplains with significant forest cover in watersheds (in the taiga zone and in the zone of coniferous-deciduous forests).

Class III - forests characterized by an average degree of manifestation of the water protection role. This class includes: forest areas of significant size on gentle slopes and watershed plateaus with moderate forest cover in watersheds in the forest-steppe zone, in the zone of coniferous-deciduous forests, and partly in the taiga zone; pine forests on fresh and moist sands and sandy loams with flat relief in the forest-steppe zone and in the zone of coniferous-deciduous forests; floodplain forests on loamy soils with significant forest cover on the slopes of watersheds in the zone of coniferous-deciduous forests.

Class IV - forests of low degree of manifestation of water protection and especially protective role. This class includes large forests located in the taiga zone. This classification was developed for the lowland forests of the European part of the USSR. With some changes and additions, it can also be used in the lowland forests of Siberia. As already noted, mountain forests have a high degree of manifestation of water protection properties, and all of them, with the exception of forests on gentle slopes, should be assigned to classes I and II. In mountainous regions, in addition to the forests listed in the considered classification, forests growing along the borders with high-altitude treeless spaces, on steep slopes with fine soils and in avalanche-prone areas, in places where mineral springs are equipped, along edges and talus, play a large water-protective role. around places of formation of icing and glaciers and others. Among the conditions that determine the hydrological regime, the leading place in mountainous regions belongs to altitudinal belt complexes, which differ in natural and climatic features. In each such belt there is a peculiar hydrological regime, in particular, the flow regime. According to the results of studies conducted in the basin of about. Baikal, it has been established that the tundra-bald mountain complex, occupying 15% of the area, forms 28% of the runoff coming from this territory into the lake (Lebedeva, Uskov, 1975). The cedar-taiga belt, which occupies 4.3% of the total area, forms 8% of the flow entering the lake, the cedar-fir and fir (6.8% of the area) - 7.4, the deciduous-taiga (37.5% of the area) - 39.4, subtaiga-steppe (19.5% of the area) - 10, meadow-steppe (17% of the area) - 17%. Altogether, the mountain-taiga belt transfers 70-80% of precipitation into ground runoff, while the lower mountain belt only 30-50%. Similar data were obtained in other regions.

According to I.P. Koval (1976, 1977), in the high-mountain belt of the Black Sea coast of the Caucasus, occupied by highly productive plantations, where 2000-3000 mm of precipitation falls annually, infiltration into the underlying rocks prevails in the water balance (65%); total evaporation is 29%, slope runoff accounts for 6% of the annual precipitation, and the share of surface runoff is insignificant - 0.01%. Forests in this belt contribute to the accumulation of snow in winter (175 mm), when snow melts, water enters the soil and is consumed for 6 or more months. A different picture is observed in the lower belt, where 500-800 mm of precipitation falls and low quality oak forests grow. Here, the main share of the expenditure part of the water balance (65%) falls on total evaporation, while runoff and infiltration account for 35% of precipitation. The research results show that the areas under oak plantations of the North Caucasus cannot regulate the drainage flow of rainfall with an intensity of more than 30-40 mm, while the soils under beech stands in the upper belt can hold 2.5-3 times more water (Koval, 1976). According to V. I. Tarankov (1970), in the mountain forests of Primorsky Krai, with an increase in altitude from 650 to 1050 m, the thickness of the snow cover increases 3 times, and the water supply more than 2 times. These examples convincingly show that different mountain belts perform far from the same hydrological role, so the economic regime in them should have significant differences. The classifications of forests according to their water-protective value, proposed by I.V. Tyurin and other authors, are used in forest management, scientific research, division of forests into groups, and were also taken into account when developing the “Basic Provisions for Final Felling in the Forests of the USSR” (1967) and regional felling rules. According to the Fundamentals of the Forest Legislation of the USSR and the Union Republics (Article 15), forests of state importance are divided into the first, second and third groups, and collective farm forests - into the first and second groups. The first group includes: water protection forests (forbidden strips of forests along the banks of rivers, lakes, reservoirs and other water bodies, including forbidden strips of forests that protect spawning grounds for valuable commercial fish); protective forests (anti-erosion forests, including forest areas on steep mountain slopes, state protective forest belts, belt forests, steppe forests and ravine forests, protective forest belts along railways, highways of national, republican and regional significance, especially valuable forest tracts) ; sanitary-hygienic and health-improving forests (urban, green areas around cities, other settlements and industrial enterprises, sanitary protection zones of water supply sources and sanitary protection districts of resorts); forests of reserves, national and natural parks, protected forest areas, as well as forests of scientific or historical significance, natural monuments, forest parks, forests of walnut-producing zones, forest fruit plantations, tundra and subalpine forests.

In the forests of the first group, felling is carried out by methods aimed at improving the forest environment, the condition of forest stands, water protection, protective and other properties of the forest and the timely and rational use of mature wood. The second group includes: forests in areas with a high population density and a developed network of transport routes that have a protective and limited operational value, as well as forests with insufficient forest resources, which require a stricter forest management regime to maintain their protective functions; all collective farm forests not included in the first group. In the forests of the second group, fellings for the main use are carried out by methods aimed at restoring forests with economically valuable tree species and at preserving their protective and water protection properties, which allow for the effective exploitation of these forests. The third group includes forests in densely forested regions, which are of primary operational importance and are designed to continuously meet the needs of the national economy in wood without compromising the protective properties of these forests. Forest areas that perform an exceptionally large water protection role are classified as especially protective and they provide for a limited forest management regime.

Specially protected areas are allocated in the forests of the first and second groups, and in mountain forests in all groups. In mountainous areas, forest strips 250-500 m wide along the borders with mountain tundra and subalpine meadows should be included in the category of specially protected areas. The soils of these lands are usually characterized by low water permeability and surface runoff occurs here during snowmelt and summer showers. The forest belt located below these treeless spaces is distinguished by soils with favorable physical properties. This ensures the transfer of surface runoff from the overlying treeless spaces to the subsurface runoff. In addition, a thick layer of snow accumulates in forest strips located near treeless spaces. In the Northern Urals, for example, the height of the snow cover in such forests is 4-5 m. This thick snow cover, containing a huge amount of water, melts slowly and maintains a high water level in the rivers during the dry period. Forest strips along the borders with treeless areas also contribute to the preservation of the forest environment in the lower felling areas, which creates favorable conditions for natural and artificial reforestation. The role of these forests on avalanche-prone slopes is great: they extinguish the kinetic energy of avalanches, protecting the lower-lying settlements, agricultural and forest lands from their devastating effect. In those cases where there are permanent channels of snow avalanches, strips of forest 100 m wide along these channels should be considered especially protective. In mountain forests, strips of forest (up to 100 m wide) along the edges of cliffs and scree should also be considered as especially protective. By converting surface runoff into soil and ground runoff, they reduce the growth of areas unsuitable for growing forests. All areas with access to the surface of stones and rocks, as well as forests along ridges and watersheds, should also be classified in the above category. As already mentioned, forests occupying steep slopes are of great water protection and protection value, and they are also classified as especially protective. In the lake basin Baikal, this category includes all forests growing on slopes with a steepness of more than 25 °, in other mountainous areas - on slopes of 30 °.

The role of forests along the hydrographic network and around reservoirs and reservoirs is great and multifaceted. These forests protect places where groundwater seeps out from siltation. It is known that surface and underground waters located in the upper layers of the earth are closely interconnected. This relationship is most clearly manifested in river valleys and near water bodies. It is often possible to observe how small streams turn into rivers due to the drainage of springs. Thanks to the wedging out of groundwater, the rivers are fed during low-water periods (summer and winter). The forests of river valleys protect groundwater from pollution, since during floods, when a significant part of the floodplain is flooded, groundwater is fed, and then it is backed up. It should be borne in mind that underground fresh water, especially located in the upper layers of the earth, is an important, and very often the only source of fresh water supply for cities, other settlements and industrial enterprises. Forests growing directly along the hydrographic network and around water bodies are also of great sanitary, hygienic and aesthetic importance. They are a place of rest for the population. At present, almost half of the inhabitants of cities and towns rest near water sources. Therefore, in all riverine forests, including those in forbidden areas, it is necessary to allocate especially protective areas. The approval of the Fundamentals of the Forest Legislation of the USSR and the Union Republics necessitates a revision of certain issues related to the allocation of restricted areas and especially protective areas in riverine forests. For example, in the Southern Urals, in the upper reaches of the river. White, out of a total length of 5709 km of watercourses, forbidden strips are allocated for 484 km, which is 8.5% of the total length of watercourses. On the Ufa Plateau (Bashkir ASSR), the length of the forbidden strips does not exceed 13% of the length of all watercourses. A similar pattern is observed in other areas. 148 It is appropriate to note that the current practice of allocating prohibited strips along rivers has significant shortcomings.

Despite the fundamental differences in the structure of river valleys in lowland and mountain forests, forest management still uses the same standards when allocating forbidden strips. The width of the allocation of such bands in some cases does not have a proper scientific justification. Often in mountainous areas, areas located on slopes facing the opposite side of the river are included in the forbidden strips. If in the specially protected areas, the allocation of which is provided for in the forbidden strips, forestry is carried out, as a rule, taking into account the preservation of water protection and protective functions, then this cannot be said about those riverine forests in which the forbidden strips have not yet been allocated. There, timber harvesting, especially in the forests of the third group, is carried out by continuous cutting areas, as a result of which erosion processes and landslides often occur along the banks of rivers and streams. Sometimes, as a result of logging and excessive grazing, there is no renewal of tree species, and the bedrock banks are represented by bare slopes with access to the surface of bedrock. Under the influence of clear felling in many cutting areas, there is an increased change of coniferous species by deciduous species, and such stands, especially at a young age, do not always satisfactorily perform water protection and protective functions. In order to ensure that the forests fulfill their water protection and protective functions and create conditions for fish spawning, it is necessary to establish an appropriate management regime not only in the designated forbidden areas, but also in all riverine forests. Along watercourses, around reservoirs and reservoirs, it is necessary to allocate especially protective areas.

The width of such areas in different natural and geographical conditions should be different. For example, in the mountain forests of the Urals, studies (Pobedinsky and Churagulov, 1975) have shown that it is advisable to allocate especially protective areas on large rivers from the water's edge to the top of the first slope facing the reservoir or the river. In this region, in the overwhelming majority of cases, the width of such sections will usually not exceed 0.5-0.8 km. Along the rest of the mountain rivers in this region, the width of the sections should be from 50 to 200 m on each bank of the river. When determining the width of the strips, the silvicultural properties of tree species, the steepness and length of slopes, and soil conditions should be taken into account. In cases where forbidden strips or especially protective areas located along rivers and around reservoirs are adjacent to agricultural lands, the surface runoff formed on these lands often passes through the forest strip in a concentrated stream, carrying with it a huge mass of erosive material, mineral and organic fertilizers . This contributes to the siltation of riverbeds, lakes and reservoirs, as well as the deterioration of water quality in them. In order to ensure the transfer of surface runoff into subsoil runoff and to protect water from chemical, bacteriological and physical contamination, it is necessary to create the simplest hydraulic structures (for example, water-retaining shafts, etc.) in the places where such flows arise. The listed and some other specially protected areas are common and should be allocated in all natural and economic regions, other especially protected areas are regional and are allocated in certain areas. For example, in Transbaikalia, it is necessary to single out strips of forest (up to 100 m wide) as such areas along the places where icing and snowfields form: they create conditions for the gradual melting of snow and ice. In the spring (May-June), there is little precipitation in these areas, therefore, before intense summer precipitation, many streams are fed by the slow melting of snowfields and icings.

In areas with developed karst, the entire layer of melt water formed on karst watersheds during the period of snow melt enters karst formations, and from there into the hydrographic network (Pismerov, 1973). Observations have shown that in the process of tractor skidding, especially during the snowless period, many karst funnels become silted, losing the ability to absorb melt and storm water. As a result, water quickly drains from the soil surface. Therefore, during the period of snowmelt and showers, the flow of water in the rivers increases sharply, while in other periods it decreases. To eliminate these negative phenomena, it is advisable to leave protective areas around karst funnels when diverting cutting areas to the felling and prohibit the laying of skid trails along them. Selective and sometimes gradual felling should be carried out in specially protected areas. Selective cuttings are carried out mainly in forests of different ages, the rest in even-aged forests. At each reception, no more than 20-25% of the growing stock should be removed. Logging by continuous narrow cutting areas should be allowed in specially protected areas only for silvicultural reasons. Logging operations with all felling methods should be carried out mainly in the winter period and in compliance with a number of forestry requirements, which were discussed in the previous section.

Coniferous forests occupy vast areas in the Northern Hemisphere. This zone is located south of the tundra and is called the taiga. Soils in the taiga are podzolic; in mixed forests - sod-podzolic. To the south, coniferous forests give way to deciduous ones. Conifers, with the exception of larch, are evergreen trees.

The Soviet Union is the richest country in the world with forests. Of the 3 billion hectares of forest on the whole earth, more than 1 billion hectares are located in the USSR. 80% of our forests consist of the most valuable conifers.

The coniferous forests of the USSR and Western Europe consist of pine, spruce, fir, and larch. Daurian larch forms extensive forests in Eastern Siberia.

North America is also rich in coniferous forests, especially the strip along the Pacific coast, from 42 to 62 ° N. sh. Some of the coniferous forests of this region belong to the laurel type forests, but in the Sierra Nevada mountains, under different climatic conditions, coniferous forests grow. At an altitude of 1500-2500 m above sea level, there is a tree that has the thickest trunk on Earth - the giant sequoia. The tree reaches 150 m in height and 15 m in diameter. The giant sequoia lives up to 4 thousand years. In the Sierra Nevada mountains, there are 32 patches of sequoiadendron forest. Separate giant trees are named after their own names: "Mother of the forests", "Father of the forests", "Grey-haired giant". In the USSR, the giant sequoia is bred on the Black Sea coast and in some regions of Central Asia.

To the east and northeast of the Pacific coast, the number of species of conifers decreases. And only Canadian forests are richer in species of coniferous forests in Europe. In Canada, there are several types of pines: flexible pine, resinous pine, white pine; several types of spruce, two types of fir and two types of larch.

In Western Europe, coniferous forests are found only in the mountains. Scotch pine and tall spruce (common) grow there, and on the plains there are exclusively deciduous forests.

The plains of the European part of the USSR are characterized by spruce forests. They are named according to the grass cover: sour spruce forest (with a predominance of oxalis plants in the grass cover), lingonberry spruce forest (with a predominance of lingonberries), blueberry spruce forest and a number of other types.

We mistakenly call cedar one of the types of pine, namely Siberian pine. She gives the so-called pine nuts. Korean pine grows in the Far East, also incorrectly called Korean cedar. Its seeds are somewhat larger than those of Siberian pine and have a harder skin. On Earth, 4 types of real cedar are known: Himalayan cedar - grows in the Himalayas, Atlas cedar - in the Atlas Mountains in North Africa, Lebanese cedar - in the mountains of Lebanon in Western Asia and short-coniferous cedar - in the mountains of the island of Cyprus.

Coniferous forests are very valuable. They are used to obtain construction and ornamental material, fuel, paper and other products. The wood chemical industry produces film, plastics, viscose, alcohol, synthetic rubber, turpentine, camphor and many other substances from wood.

A large number of coniferous trees growing on Earth can be cultivated in our country. At the Botanical Institute of the USSR Academy of Sciences, scientists summarized the experience of our botanical gardens and parks, compiled a list of conifers that can be bred in various regions of the USSR.

Only on the southern coast of Crimea and the Black Sea coast of the Caucasus can more than 100 species of coniferous trees and shrubs be cultivated instead of a dozen species that are found there in the wild.

Summer green forests are distributed mainly in the Northern Hemisphere. They grow on gray forest and brown forest soils. In the Southern Hemisphere, such forests are found only in South America in Patagonia.

In summer green forests, two groups of trees (and shrubs) are distinguished: broad-leaved and small-leaved. Beech, oak, maple, linden and other broad-leaved trees have a rather large leaf blade. Such a leaf evaporates a lot of water.

In small-leaved trees (birch, aspen, alder and some others), the leaf blade is smaller. These tree species were formed in more severe conditions than broad-leaved ones.

Broad-leaved forests are characteristic of the Atlantic states of North America, Western Europe, and the European part of the USSR. In Asia, they occupy the southern parts of the Far East, most of East China, and Japan.

The broad-leaved forests of North America, in comparison with the forests of Eurasia, are rich in tree and shrub species. Large-leaved beech prevails in the forests, reaching 40 m in height and more than 1 m in diameter. In autumn, its leaves turn red-brown and fall off in October - December. Large-leaved beech is used in gardens and parks of the southern regions of the USSR as an ornamental tree.

In the forests of North America there is a lot of sugar maple, reaching 35 m in height. It has valuable wood. The sap of the tree contains 2 to 5% sugar and is used for sugar making. In the beech forests of North America, there is a good grass cover, many shrubs, and lianas are found. Virginia grapes grow here, which we call “wild grapes”. It is bred near terraces and arbors. He covers them with a solid green wall.

Oak forests occupy more continental areas in North America. They are characterized by several types of oaks, numerous types of maples, several types of walnut. All these trees are also found in the USSR, but in our country they are represented by other species. In North America, there is also a tulip tree and creepers in oak forests.

Western Europe is characterized by beech and oak forests. However, the types of beech and oak are already different there. The forest beech, or European, is not inferior in height to the American beech, sometimes even exceeds it. The beech that grows in the Crimea is very similar to the European beech, but it is a special species - the Crimean beech. In the Caucasus, beech forests are formed by oriental beech.

Beech can be grown in the forest zone of the European part of the USSR up to Moscow and Leningrad.

In contrast to the forests of North America, the beech forests of Eurasia have almost no grass cover and shrub layer. On the plains of the European part of the USSR, beech forests grow in the western part of the Ukrainian SSR (Stanislav, Volyn, Khmelnitsky and other regions).

The oak forests of Western Europe consist mainly of sessile oak. On the plains of the European part of the USSR, another type of oak is already widespread - the pedunculate oak. Broad-leaved forests with a predominance of oak extend almost in a continuous strip to the Ural Range. In the south they border on the steppes, and in the north they are replaced by coniferous forests. Pedunculate oak is a very valuable species. Its wood is used for construction and various crafts (parquet, plywood, furniture, etc.). The bark is used for tanning leather. Acorns are used to make a coffee substitute. Pedunculate oak is the main species in the field-protective forest belts of the southern half of the European part of the USSR.

Other types of oak, linden, maple, elm grow in the east of Asia, as well as the Amur cork tree and other trees.

Small-leaved forests - birch, aspen and alder - appear after cutting down coniferous and broad-leaved forests; they are called secondary. But in a number of places, small-leaved forests are primary (primary). In the more humid climate of northeast Asia, small-leaved trees grow: fragrant poplar, chosenia, Cajander birch.

The Cis-Urals and Western Siberia are characterized by forests of warty birch and downy birch. Birch, aspen and alder are often found in the coniferous and broadleaf forests of North America and Eurasia.

What forests are still left in the world
Review by Polit.ru expert, ecologist, doctor of agricultural sciences Valentin Strakhov

According to the Food and Agriculture Organization of the United Nations (FAO), the total forest area of ​​the world exceeds 3.4 billion hectares, or 27% of the earth's land area. FAO estimates are based on the definition that all ecological systems with a tree cover of at least 10% in developing countries and at least 20% in developed countries are identified as forests.

In addition, according to the accepted methodology for classifying forests, 1.7 billion hectares of land occupied by trees and shrubs must be added to this area. More than half of the world's forest area (51%) is located on the territory of four countries: Russia - 22%, Brazil - 16%, Canada - 7%, USA - 6%

An estimate of the total timber stock in the world's forests has been obtained by FAO by summarizing data from 166 countries covering 99% of the world's forest area. It amounted to 386 billion cubic meters in 2000.

The total amount of aboveground woody biomass in the world is estimated at 422 billion tons. About 27% of the aboveground woody biomass is concentrated in Brazil and about 25% in Russia (due to the area).

The average amount of woody biomass per hectare of the planet's forests is 109 tons/ha. The maximum amount of woody biomass per hectare is recorded for South America as a whole. The largest stock of timber per hectare was also noted here (in Guatemala - 355 m3/ha). The countries of Central Europe also have very high timber stocks per hectare (286 m3/ha in Austria).

The Global Forest Assessment is based on information provided by each country to FAO based on a recommended format. These data are also usually combined according to the allocated zones of forest growth: tropical, temperate and boreal zones based on the conditional division of the surface of the globe into physical and geographical zones.

Forest zones are called natural land areas of the boreal, temperate, subtropical, tropical, subequatorial and equatorial belts, in the natural landscapes of which forest tree and shrub vegetation predominates. Forest zones are common in conditions of sufficient or excessive moisture. The most typical for the growth of forests is a humid or humid climate. According to

According to the geomorphological classification, the climate of areas with excessive moisture is considered humid when precipitation exceeds the amount of moisture used for evaporation and seepage into the soil, and excess moisture is removed by river runoff, which contributes to the development of erosive landforms.

The typical vegetation of landscapes with a humid climate is the forest. There are two types of humid climate: polar - with permafrost and phreatic - with groundwater.

The tropical forests of the world cover an area of ​​1.7 billion hectares, which is about 37% of the land area of ​​countries located in the tropical zone of our planet. In the tropics, subequatorial monsoon forests, equatorial tropical rainforests, tropical humid evergreen, humid tropical deciduous and semi-deciduous forests, including mangrove forests and savannas, grow.

All forests of this belt of the earth develop on the so-called red soils - ferrallitic soils, which were formed on the weathering crust of the ancient dry land of the earth, which underwent deep weathering (ferrallitization), as a result of which almost all primary minerals were destroyed. The content of humus in the upper horizon of these soils is from 1-1.5 to 8-10%. Sometimes, glandular shell crusts form on the soil surface.

Ferrallitic soils are common in South and Central America, Central Africa, South and Southeast Asia, and Northern Australia. After deforestation, hevea plantations are created on these soils to collect natural rubber, oil or coconut palms, as well as a classic set of tropical crops: sugar cane, coffee, cocoa, banana, pineapple, tea, black and white pepper, ginger, etc. culture.

The forest zones of the temperate zones of the Northern and Southern Hemispheres include the taiga zone, the zone of mixed forests, the zone of broad-leaved forests and the monsoon forests of the temperate zone.

A characteristic feature of the forest zones of temperate zones is the seasonality of natural processes. Coniferous and deciduous forests are widespread here with a relatively simple structure and a small variety of vegetation cover. Podzolic and burozem types of soil formation predominate.

Temperate forests cover an area of ​​0.76 billion hectares in five regions of the world: eastern North America, most of Europe, the eastern part of the Asian subcontinent, a small part in the Middle East and Patagonia (Chile).

Boreal forests grow in the latitudinal zone between the arctic tundra and temperate forests. The total area of ​​forest lands in the boreal belt of the planet is estimated at 1.2 billion hectares, of which 0.92 billion hectares are closed forests, including 0.64 billion hectares of forests called exploitation.

Boreal forests grow mainly in the Northern Hemisphere. Their total area in North America and Eurasia is almost 30% of the total forest area of ​​the planet.

In general, the area of ​​boreal forests is 82.1% of the total forest area of ​​the six countries in which they grow. In Canada, boreal forests make up 75% of forests, in the USA (Alaska) - 88%, in Norway - 80%, in Sweden - 77%, in Finland - 98% and in Russia - an average of about 67%.

Tropical forests are characterized by thick weathering crust and intense runoff. The subzone of permanently moist forests is dominated by evergreen forests with exceptional species diversity on red-yellow lateritic soils. In the subzone of seasonally wet forests, along with evergreen forests, deciduous forests on red ferrallitic soils are common.

Zones of equatorial tropical forests are distributed on both sides of the equator in South America, Africa, Southeast Asia, and on the islands of Oceania. In the zones of equatorial forests, there is almost no seasonal rhythm of natural processes, moisture is abundant, temperatures are constantly high, rivers are rich in water, soils are podzolized lateritic, along the sea coasts there are mangrove communities.

The forest that grows here is commonly known as the evergreen rainforest. This forest has become a symbol of the struggle for the conservation of forests and the conservation of biological diversity, as it is a multi-tiered tree formations that grow in conditions of year-round moisture and has a high density of animal population, especially in the upper layers of the forest.

There are already less than 1 billion hectares (718.3 million hectares) of such forests left on the globe, mainly in Brazil, i.e. about 41% of the total rainforest area, or about 16% of the planet's forest area.

Subequatorial monsoon forests are common in Central and South America, Africa, southern Asia and northeast Australia. In these zones, the climate is characterized by the dominance of the equatorial monsoons. The dry season lasts 2.5-4.5 months. The soils are red-colored lateritic. Mixed deciduous-evergreen and deciduous forests predominate.

Humid tropical evergreen, semi-deciduous and deciduous forests are the predominant type of vegetation in the eastern sectors of the continents within the tropical zones of the Northern and Southern Hemispheres (south of Florida, Central and South America, India, Madagascar, Southeast Asia, Australia, the islands of Oceania and the Malay Archipelago. They occupy mainly the windward slopes of mountainous areas.The climate is tropical humid or seasonally humid with a predominance of humid oceanic trade winds.

According to the Forest Information System (FORIS) developed by the FAO, out of the total area of ​​tropical forests (1756.3 million ha), lowland forests account for 88%, mountain forests for 11.6%, and highland areas without tree vegetation for 0.4%. Among the lowland tropical forests, the largest area is occupied by rain evergreen tropical forests (718.3 million hectares in 1990), the forest cover of these territories is 76%. They are followed by humid tropical deciduous forests, the area of ​​which is 587.3 million hectares (forest cover 46%). Dry deciduous tropical forests occupied only 238.3 million hectares (forest cover 19%). The area of ​​mountain forests was 204.3 million ha (forest cover 29%).

Lands freed from the virgin rainforest for agricultural use, very quickly lose their fertility. Abandoned agricultural land is overgrown for several years with the so-called secondary rainforest; secondary after the virgin.

The most typical feature of the secondary tropical forest is the depleted and fairly uniform in terms of ecological characteristics of the species composition of trees - edificators.

Tree species of the secondary tropical forest are characterized by relative photophilousness, rapid growth and the ability to disperse seeds efficiently, i.e. less reliance on consortial relationships with seed-dispersing animals than primary rainforest trees. But as the secondary forest develops, it approaches the parent formation more and more in its appearance.

Tropical forests are heterogeneous. The total number of woody plants in tropical forests exceeds four thousand. At the same time, the number of main forest-forming tree species exceeds 400 species. Therefore, the tropical forest is a complex mosaic of evergreen, semi-evergreen (semi-deciduous), mixed, deciduous and coniferous forests, which is formed under the influence of orographic and edapho-climatic factors.

Such edapho-climatic types of tropical forest formations as savannahs, bamboo thickets, and mangrove forests stand apart.

Unlike other forest formations, the species composition of natural mangrove forests is small. Actually mangrove trees, which determine the specific appearance of this formation, are species of two families Rhizophoraceae (genus Rhizophora and Bruguiera) and Verbenaceae (genus Avicennia); the core of the formation is formed by 12-14 species of mangrove trees.

It is believed that with the help of mangrove forests, not only the consolidation, but also the increment of the landmass of the countries of the Pacific region takes place.

The mangrove forests of the world have been studied quite well and in detail. To a large extent, this is due to their diverse and ecologically important role, ranging from creating specific conditions for the reproduction and habitat of numerous marine and freshwater fish, crustaceans, etc., up to the use of mangrove wood for fuel, charcoal (from Rhizophoza), processing etc.

In the countries of the Asia-Pacific region with their ancient civilizations, artificial mangrove forests are also widespread, in which up to 40% are Melaleuca leucadendra trees.

A significant part of the world's population lives in the forest subtropical zone. It is formed by a combination of forest natural zones of the subtropics of the Northern and Southern Hemispheres, sometimes considered as zones of monsoon mixed forests, a typical example of which are the Mediterranean zones. Forest subtropical zones are characterized by mild winters, year-round vegetation of plants, and significant differences in landscapes on the slopes of different exposures.

Forest - a set of woody, shrubby, herbaceous and other plants, as well as microorganisms, animals and biologically interconnected in their development and influencing each other and the external environment.

Area and structure of forests relative to the entire earth's surface, % Earth's surface Forests 69 31 28.8 Natural forest 2.2 Forest plantations

Lands of the Forest Fund Forested Lands covered with forest vegetation Not covered with forest vegetation Self-sowing Forest crops Non-forest Forest nurseries, plantations Natural sparse areas Reforestation Fund Burnt areas, wastelands Roads, clearings Swamps, waters, sands Other lands Dead forest stands Orchards, berry fields Hayfields, pastures Arable lands, estates Non-closed forest crops Clearings, clearings

Forest plantations - a set of woody and non-woody plants that have passed the same history of development in homogeneous forest conditions. Include in their composition: Tree stand Shrubs Undergrowth Undergrowth Living ground cover

Indicators used to characterize the forest: 1. Completeness. 2. Closeness of the canopy. 3. Quality class. 4. Classes of fire danger. 5. Forest conditions. 6. Predominant breed.

Forest type is the main unit of forest classification, uniting forest areas that are homogeneous in composition of tree species, other tiers of vegetation, a complex of forest conditions (climatic, soil and hydrological).

Main forest types Primary forest types Derived forest types Develop in nature without human influence or natural disasters Replace primary ones as a result of human and natural factors

The objectives of the classification of forest types: 1) description of the forest and the conditions of its growth; 2) highlighting the features of the stand itself (composition, age structure); 3) assessment of the quality of wood for economic purposes; 4) choice of the most successful way of reforestation.

Classification of forest types according to the ground cover for Siberian stone pine forests Group of types Mossy Forb Broad grass Grass marsh Sphagnum Type Prevalence, % sphagnum sphagnum 13

Classification of forest types according to soil conditions Very dry (Xerophilic) Dry (Mesoxerophilic) Fresh (Mesophilic) Wet (Mesohygrophilic) Wet (Hygrophilic) Bogs (Ultrahygrophilic)

Peculiarities of forest typology abroad 1) forest types are the basis in richly forested countries with a predominance of forests of natural origin (Finland); 2) types of forest conditions are taken as the basis in countries with a predominance of artificial plantations (Poland, Hungary, Romania); 3) some countries combine both of these principles (England); 4) geographical features are taken into account in a number of countries (France, Germany, USA); 5) the history of forest stand development is taken into account in some countries (Australia, Austria); 6) when identifying types of mountain forests, additional features are used (altitude zonality, slope exposure, direction of prevailing winds, snow cover depth, cold index).

The practical significance of forest typology 1) assessment of the quantity and quality of wood resources; 2) characteristics of tree stand productivity, assortment composition and wood quality; 3) determination of resistance to adverse effects: diseases, pests, fires, windfall; 4) taking into account when planning forestry activities: felling, clearing cutting areas, silvicultural work and promoting natural regeneration; 5) taking into account the type of forest when planning forest protection work and work to protect the forest from fires.

According to the prevailing life forms, the communities of woody vegetation are subdivided into: 1) forests proper - with the dominance of forest stands; 2) light forests and shrubs - with a large proportion of shrub species.

According to the species composition, forests are divided into 1. Coniferous: pine, spruce, fir, larch, cedar, juniper. 2. Hardwood: oak, beech, hornbeam, ash, maple, elm, saxaul. 3. Soft-leaved: birch, aspen, alder, linden, poplar, willow.

According to the species composition, forests are 1. Spruce forests, fir forests, pine forests, larch forests are light coniferous and dark coniferous forests. 2. Birch forests, aspen forests, alder forests are small-leaved forests. 3. Oak forests, beech and hornbeam forests are broad-leaved forests.

According to the density of forest stands, forests are divided into 1) closed forests - trees of any size cover at least 20% of the area; 2) sparse forests ("open forests", woodlands) - this is a small forest with a predominance of shrub species and undergrowth.

By productivity, forests are divided into 1) productive capable of producing - forests, physically commercial timber yields; 2) unproductive - forests capable of producing only fuel wood due to unfavorable habitats. conditions

According to the most important forest regions, 1) tropical forests are distinguished; 2) mixed temperate forests; 3) coniferous forests of northern latitudes.

Location of the most important forest biomes 1. Tropical rainforests - South America, Central Africa, South Asia, Hawaii and Australia. 2. Deciduous forests - North America, Europe and Asia. 3. Coniferous forests - Canada, Alaska, Northern Asia and Northern Europe.

Depending on the latitude, tropical forests are: 1. Tropical rainforests - equatorial evergreen forests (selva, gilea, jungle). 2. Dry deciduous tropical forests - fall off during the drought period. 3. Evergreen subtropical forests - eucalyptus groves of Australia.

Classification of the Earth's climates according to V.P. Koeppen Types of climatic zones Types of climate Climate with dry winter (w) A Humid tropical zone without winter Climate with dry summer (s) Uniformly humid climate (f) B Two dry zones, one in each hemisphere Steppe climate (BS) Desert climate (BW) Dry winter climate (w) C Two moderately warm zones without regular Dry summer climate (s) of snow cover Uniformly humid climate (f) Dry winter climate (w) D Two boreal zones climate on continents with sharply defined borders Climate with dry summer (s) in winter and summer Uniformly humid climate (f) Tundra climate (ET) E Two polar regions of snowy climate Climate of eternal frost (EF)

Geographical zones of the Earth Geographical zones Location of the zone Geographical zones Northern polar zone North of the Arctic circle Arctic Subarctic Northern temperate zone Between the Arctic circle and the Tropic of Cancer Southern temperate Between the tropics of Cancer and Capricorn Southern tropical Northern subequatorial Equatorial Southern subequatorial Northern tropical Hot zone Between the tropics Capricorn South Temperate Zone and South Polar North Temperate Circle South Polar Zone South of the Antarctic Circle Subantarctic Arctic

Types of forests by geographical zones 1. Tropical forests 2. Subtropical forests 3. Forests of the temperate climatic zone of the Earth 4. Boreal forests

Types of tropical forests Type of forests Distribution 1. Equatorial humid tropical On both sides of the equator in South America, Africa, Southeast Asia, on the islands of Oceania 2. Subequatorial monsoonal Central and South America, Africa, southern Asia and northeast Australia 3. Humid tropical evergreen 4. Humid tropical deciduous and semi-deciduous Within the tropical zones of the Northern and Southern Hemispheres South Florida, Central and South America, India, Madagascar, Southeast Asia, Australia, the islands of Oceania and the Malay Archipelago

Tropical forest area distribution Type of forest Forest cover, % Area, Area share, mln ha % Lowland forests 76 1550.6 88 Mountain forests 29 204.4 11.6 - 7.0 0.4 - 1762 100 Highland areas not covered by tree vegetation Total

Tropical forest area distribution 11.6 0.4 Lowland forests Mountain forests 88 Highland non-forested areas

Area of ​​boreal forests in relation to the total forest area of ​​countries, % Countries Finland Share of boreal forests, % 98 Alaska (USA) 88 Norway 80 Sweden 77 Canada 75 Russia Total boreal forest area of ​​6 countries 67 82.1

Forests that perform water protection functions - 35%: forbidden strips of forests along the banks of rivers, lakes, reservoirs and other water bodies; forbidden strips of forests protecting the spawning grounds of commercial fish.

Protective forests - 45%: anti-erosion forests; protective belts of forests along railway lines, highways of federal, republican and regional significance; state protective forest belts; tundra forests; forests in desert, semi-desert, steppe, forest-steppe and sparsely forested mountain areas, belt forests.

Forests that perform sanitary and health functions - 6%: forests of green areas of settlements and economic facilities; forests of zones of sanitary protection of water supply sources; forests of zones of sanitary protection of resorts; forest natural parks.

Special purpose forests - 4%: forests of scientific or historical significance; especially valuable forest areas; walnut commercial zones; forest fruit plantations.

Protected forests - 10%: forests of state natural reserves; forests of national parks; monuments of nature; protected forest areas.

Groups of forests by economic value, location and functions performed 1. Forests of group I - forests that perform mainly water protection, protection and other functions, grouped by protection categories. 2. Forests of group II - forests growing in areas with a high population density and having a protective and limited operational value. 3. Forests of the III group - forests of densely forested areas, which are of primary operational importance and are intended to continuously meet the needs of the national economy in wood without compromising their protective properties.

Top ten countries with the largest area of ​​protected forests, 2010 Countries 1. Russian Federation 2. China 3. Brazil 4. Indonesia 5. Japan 6. India 7. Laos 8. Mozambique 9. Venezuela 10. Viet Nam Other countries Total Area of ​​protected forests, thousand hectares 71436 60480 42574 22667 17506 10703 9074 8667 7915 5131 73014 329167 Share, % 21, 70 18, 37 12, 93 6, 89 5, 32 3, 25 2, 6 3 2.4 18 100.00

Countries with the largest protected forest area, 2010 22, 2 21. 7 Russia China Brazil Indonesia 1. 6 Japan 2. 4 2. 6 2. 8 India Laos 18. 4 3. 3 Mozambique Venezuela Viet Nam 5. 3 6. 9 12.9 Other states

Forest zones are the most extensive on Earth. There are several types of forests depending on the climatic zone.

Types of forest zones

Forest natural zones are found in three climatic zones, each with several varieties.

Table. Forest types

Each species is represented by its own tree species.

Rice. 1. Forests occupy a significant part of the land

temperate forests

Taiga is located in the north of America and Eurasia. This is a zone of coniferous forests. There are two types of taiga:

  • light coniferous;
  • dark coniferous.

Light coniferous taiga is represented by pine and larch forests, which are undemanding to natural conditions.

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These tree species can grow even on permafrost.

Shrubs here are represented by the following varieties:

  • alder;
  • dwarf birches;
  • polar birches and willows;
  • berry bushes.

The light coniferous taiga is located on the territory of Eastern Siberia, Canada, and northern Eurasia.

In the European part of Russia, North America, dark coniferous taiga is common. Spruces, firs and cedars grow here. The lower tier consists of berry bushes and ferns.

Rice. 2. Taiga is one of the largest forest belts

Mixed forests occupy a narrow strip in the following areas:

  • US-Canada border;
  • north of Eurasia;
  • Kamchatka, Far East.

Here are various tree species - coniferous, broad-leaved, small-leaved. In the Far East, monsoon forests are characterized by an abundance of lianas and multi-layered. Pine, fir, aspen, birch grow in Western Siberia. Maple, elm, beech, birch grow in North America.

Another natural zone is the broad-leaved forest - located in the eastern part of North America, in Central Europe, in the Crimea and the Caucasus. The following tree species grow here:

  • ash;
  • hornbeam;
  • maple;
  • Linden.

Forests of the subtropical zone

Hard-leaved foxes are located in southern Europe, northern Africa, southern Australia. They are characterized by a tiered structure and many vines. The following tree species grow here:

  • heather;
  • myrtle;
  • holm and cork oak;
  • arbutus;
  • eucalyptus.

These trees are well adapted to life in drought conditions. The lower tier is represented by thorny shrubs.

Monsoon forests are located in the eastern regions of the continents, characterized by the highest humidity. They are represented by evergreen and deciduous tree species:

  • subtropical pine;
  • magnolias;
  • camellias;
  • laurel;
  • cypress.

Monsoon forests are cut down by man to free up areas for agriculture.

Tropical forests

Seasonally wet and permanently wet forests are located north of the equator. They are represented by eucalyptus, teak, various types of palm trees. There is a large number of vines and shrubs. What areas are covered by these forests? They grow in Australia, on the islands of the Caribbean.

The equatorial zone contains the wettest forests. Due to the fact that there is no change of seasons at the equator, and the temperature is constantly in the range of 24-28 degrees Celsius, the vegetation here is evergreen.

Various types of palms, ficuses, cocoa trees grow here. There are a lot of shrubs and vines here.

Rice. 3. The rainforest is represented by evergreen trees.

What have we learned?

The forest zone is the most extensive of all the natural zones of the Earth. There are varieties of it in almost every climatic zone. The diversity of tree species depends on climate and soil.

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