Area of ​​the world's forests. What forests are still left in the world

25. World forest resources

IN scientific literature often there is a characteristic of the role of the forest, forest vegetation as an integral part of the biosphere. It is usually noted that forests form the largest ecosystems on Earth, in which most of the organic matter planets. What do they have great importance for photosynthesis, for the normal course of the processes of stabilizing the oxygen balance of the atmosphere, the absorption of carbon dioxide, as well as for maintaining soil fertility and water purity. That they are the largest repositories of the gene pool of the biosphere, a habitat for a large number plants and animals, an important source of wood, food, fodder, technical, medicinal and other resources. In addition to all this, forests absorb noise, many air pollutants, thereby favorably affecting the quality of the environment. natural environment, and indirectly on the mood of people who find positive emotions in communion with nature. In a word, both economic and ecological, and aesthetic value forests are always valued very highly.

Various indicators are used to quantify the world's forest resources as an important part of terrestrial biological resources. The most important among them are indicators forest area, woodland(proportion of forest area in the whole territory) and standing timber stock. However, upon acquaintance with them, a rather significant difference in estimates attracts attention. If we try to compare the estimates of FAO, other international organizations and individual experts in this field, then such a difference will be detected quite easily. For example, in various sources, the global forest area is estimated at 51.2 billion hectares; 43.2; 39.6; 36.0; 34.4;

30.0 billion hectares. Accordingly, there are also large discrepancies in the indicators of the forest cover of the earth's land (37%, 32, 30, 27%, etc.), as well as in terms of timber reserves (385 billion m 3, 350, 335 billion m 3, etc.) .

This discrepancy is explained by the fact that some of these estimates refer to different categories of forest area. The highest of them refer to the area of ​​all lands of the forest fund, which, in addition to the actual forest lands, also include shrubs, sparse areas, cuttings, burnt areas, etc. The middle ones correspond to a stricter approach to the definition of forest lands, .directly occupied by forests, areas, and the lowest - to closed forests, which occupy no more than 2/3 of all forest areas and, perhaps, most accurately characterize the true forest cover of the territory. Sometimes statistics also include primary and secondary forests.

Table 28 gives an idea of ​​regional differences in the distribution of world forest resources.

The following conclusions follow from the data in Table 28. First, that Latin America occupies the leading place in the world in all important "forest" indicators. Secondly, that the CIS, North America and Africa fall into the “second tier” according to these indicators. Thirdly, that foreign Asia, which has a high overall performance, has - as one might expect - the lowest per capita forest resource endowment. And fourthly, that according to all the main indicators included in the table, foreign Europe and Australia with Oceania close the ranking of large regions.

Table 28

DISTRIBUTION OF WORLD FOREST RESOURCES BY LARGE REGIONS

* Without CIS countries.

Along with the distribution of the world's forest resources according to major regions of great interest in the world is their distribution over the main forest belts (Fig. 24). Figure 24 clearly shows the distribution coniferous forests cold zone (or coniferous boreal forests), stretching in a wide strip through the northern parts of Eurasia and North America. To the south extends the belt mixed forests temperate zone. The forests of dry areas are most characteristic of Africa (there they are represented by sparse forests and shrubs of the savannah zone), but they are also found in North and South America, in Australia. equatorial rain forests grow in a belt with constantly high temperatures And heavy rainfall north and south of the equator. Their main massifs are located in the Amazon and Congo river basins, as well as in the South and South East Asia. tropical moist forests in general, they are much worse preserved, and they should be looked for only in certain areas of Central and South America, Africa and South Asia. Finally, humid forests of the warm temperate zone are found in separate rather large areas in North and South America, East Asia and Australia.

Rice. 24. Schematic map of the forests of the world (according to I.S. Malakhov): 1 - coniferous forests of the cold zone; 2- mixed forests temperate zone; 3 - forests of dry regions; 4 - equatorial rainforests; 5 - tropical rainforests; 6 - humid forests of the warm temperate zone

Figure 24 also provides a basis for a more generalized approach to the identification of forest belts, which is more often used in educational literature. It consists in combining them into two main forest belts of the Earth- northern and southern, which are separated by a wide belt of arid territories.

Area northern forest belt– 2 billion hectares (including 1.6 billion hectares under closed stands and 0.4 billion hectares under shrubs and light forests). The largest forest areas in this belt are located within Russia, Canada, and the USA. Coniferous species occupy 67% of the total forest area, and deciduous - 33%. The diversity of species in the forests of the northern belt is not so great: for example, in foreign Europe there are approximately 250 species of trees and shrubs. Wood growth is also rather slow. Yes, in coniferous forests In Russia, on average, 1.3 m 3 grows per 1 ha per year, in Finland - 2.3 m 3, in the USA - 3.1 m 3. In the zone of mixed forests, this increase is noticeably greater.

Area southern forest belt– also about 2 billion hectares, but 97% of it consists of deciduous forests. At the same time, half of the entire forest area is occupied by tall forest, and the rest is occupied by low-density sparse forest, shrubs, and forest fallow. In the southern forest belt, the forest stand is much more diverse than in the northern one: in all tropical forests, more than 100 and even 200 various kinds trees. The average annual growth of timber per hectare here is several times greater than in the forests of the northern zone. And the average stock of standing wood reaches 250 m 3 /ha, which is tens of times higher than such a stock in some types of forests of the northern belt. Therefore, the total stock of timber in the forests of the southern belt is greater.

Naturally, the countries with the most large sizes forest areas should be sought within either the northern or southern forest belts (Fig. 25). The composition of these belts also includes countries with the highest forest cover: in the northern zone, these are primarily Finland, Sweden, and in the southern zone - Suriname and Guyana in Latin America, Gabon and Democratic Republic Congo in Africa, Papua New Guinea in Oceania.

Russia is the richest country in the world with forest resources. From Figure 25 it follows that this applies to both its forested and forested area (the latter is 22.1% of the world). The total stock of wood in the forests of Russia - 82 billion m 3 - exceeds the stocks of any large foreign region, with the exception of Latin America. This means that Russia accounts for more than 1/5 of the world's timber reserves, including almost 1/2 of the coniferous timber reserves. According to the corresponding per capita indicators (5.2 hectares and 560 m 3), it is second only to Canada. However, the forest resources of Russia are distributed very unevenly over its vast territory: almost 9/10 of the entire forested area is located in the taiga zone, especially within Eastern Siberia and the Far East.

Rice.25. Top ten countries by forest area

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BIOLOGICAL RESOURCES

The biomass of the Earth is created by plant and animal organisms.

Plant resources are represented by both cultivated and wild plants. There are almost 6 thousand species of cultivated plants. But the most common types of crops on Earth are only 80-90, and the most common are only 15-20: wheat, rice, corn, barley, sweet potato, soybeans, etc.

Among the wild vegetation, forest vegetation prevails, forming forest resources. Like land, these are exhaustible but renewable multipurpose resources. World forest resources are characterized by three main indicators: the size of the forest area (4.1 billion hectares), forest cover (31.7%) and standing timber reserves (330 billion m 3), which, due to constant growth, increase annually by 5.5 billion m 3 . It would seem that under these conditions it is premature to talk about the threat of a shortage of forest resources. But that's not the case at all.

Wood has long been widely used as a building and ornamental material; the more it applies to our time. And today the demand for firewood is growing, and at least 1/2 of all wood harvested in the world is used for this purpose. Finally, over the millennia, beginning with the Neolithic, when agriculture arose, forests were reduced to arable land and plantations. In the last two hundred years alone, the land cover of the earth has been halved and deforestation has become rampant. It is associated with the expansion of soil erosion, and the reduction of oxygen reserves in the atmosphere.

The area of ​​forests in the world annually decreases by at least 20 million hectares, or 0.5%. World timber harvesting in the near future may reach 5 billion m 3 . This means that its annual annual growth will actually be fully utilized.

The forests of the world form two huge belts - northern and southern.

Table 15. Distribution of forest area by major regions.

The northern forest belt is located in the temperate and partly cold and subtropical climates. It accounts for 1/2 of all forests in the world and the same part of the timber stock. The main logging operations are carried out here, especially especially valuable timber coniferous species. Despite intensive exploitation, thanks to reforestation and afforestation (in the USA, Canada, Finland, Sweden), the total forest area of ​​the northern belt is not decreasing.

The southern forest belt is located mainly in the tropical and equatorial climates. It accounts for 1/2 of all forests and the total stock of timber. Previously, it was used mainly for firewood, in Lately exports to Japan increased many times, Western Europe, USA. The forests of the southern belt are also heavily damaged by the slash-and-burn system of agriculture that has been going on for many hundreds of years, and extensive pasture cattle breeding. All this leads to catastrophically fast deforestation of this belt.

Moist evergreen tropical forests still occupy more than 1 billion hectares, with more than half of their area - in Latin America. However, Latin America and Asia have already lost 40% of such forests, and Africa 50%. Scientists believe that these forests are under the threat of complete destruction by the middle of the 21st century. big works conservation rainforest initiated under the leadership of the UN, but so far they have not brought the desired results. Therefore, measures for the rational use of forest resources continue to be extremely relevant.

Table 16. The most and least forested countries in the world

Most wooded countries	Forest cover, %	Least wooded countries	Forest cover, %
Suriname		Oman
Papua New Guinea		Kuwait
Guyana		Central African Republic
Gabon		Saudi Arabia
DR Congo		Jordan
Finland		Iceland
Cambodia		Egypt
North Korea		UAE
Sweden		Haiti
Japan		Niger
The Republic of Korea		Algeria
Laos		Afghanistan
Brazil		South Africa
Indonesia		Syria
Guinea

Countries with largest sizes forest areas
Russia (765.9 million ha), Canada (494.0), Brazil (488.0), USA (296.0), DR Congo (former Zaire), Australia, China, Indonesia, Peru, Bolivia

Additional information:

34 VTL account for 10 countries: Brazil, Indonesia, Zaire, Peru, Colombia, India, Bolivia, Papua New Guinea, Venezuela, Myanmar.

In terms of forest area per capita, the leaders are: Guiana, Suriname, Gabon, Congo, etc.

are shrinking woodlands in Russia, almost all forests have been reduced to nothing in El Salvador, Jamaica and Haiti.

The resources of the animal world, being also an integral part of the biosphere, are another vital resource of mankind, belonging to the category of renewable. On the the globe there are several million species of animals (there are much more of them than plants), some of them are domestic, others are commercial, etc. And together, plants and animals form genetic fund (gene pool) planet, which also needs protection from impoverishment.

From 1600 to 1995, more than 600 species of animals have already disappeared on Earth, and another 35 thousand species are under the threat of destruction (not counting invertebrates). Particularly intense pressure animal world Europe, where many species of mammals are on the verge of extinction, from 30 to 50% of all bird species. An example of the impoverishment of the gene pool in Africa and Asia is the catastrophically rapid decrease in the herd of elephants.

Preservation biodiversity, prevention of "erosion" of the gene pool is a very important task.

Tasks and tests on the topic "Biological resources"

• 6 Tasks: 9 Tests: 1

Leading ideas: geographical environment- a necessary condition for the life of society, the development and distribution of the population and the economy, while recently the influence of the resource factor on the level of economic development of the country has been decreasing, but the importance of rational use natural resources and environmental factor.

Basic concepts: geographic (environment) environment, ore and non-metallic minerals, ore belts, pools of minerals; structure of the world land fund, southern and northern forest belts, forest cover; hydropower potential; shelf, alternative sources energy; resource availability, natural resource potential (NRP), territorial combination of natural resources (TSSR), areas of new development, secondary resources; environmental pollution, environmental policy.

Skills: be able to characterize the natural resources of the country (region) according to the plan; use various methods of economic evaluation of natural resources; characterize the natural prerequisites for the development of industry and agriculture of the country (region) according to the plan; give brief description location of the main types of natural resources, single out the countries "leaders" and "outsiders" in terms of availability of one or another type of natural resources; give examples of countries that do not have rich natural resources but have reached a high level of economic development and vice versa; give examples of rational and irrational use of resources.

(composed of 97% broadleaf forests - mostly moist and tropical forests in developing countries).

In the last 200 years alone, the area of ​​forests in the world has halved. The destruction of forests at such a pace will have catastrophic consequences for the whole world, as the supply of oxygen to the world is reduced, the climate on the planet is changing.

The largest area of ​​forests has been preserved in and, the smallest -. However, the sizes of the continents are not the same, so it is important to take into account the forest cover index (the ratio of the forested area and the total area of ​​the region), as well as the size of the timber reserves and the area of ​​the forested surface per 1 inhabitant.

The problem of deforestation is becoming a very serious global problem. The forests of the northern forest belt in the economically developed countries were subjected to intensive destruction in the past, but then the forest cover was restored to a greater extent (forestation). In some countries where government conservation programs are in place, wood growth has begun to outstrip wood harvesting. And the main reason for the loss of forest and the decline in its quality in developed countries in recent decades have become acid rain(from air pollution). According to experts, the total area of ​​affected forests is about 30 million hectares.

For many centuries, the reduction in the area of ​​\u200b\u200bforests on the planet practically did not hinder the progress of mankind. Recently, however, this process has begun to have a negative impact on the economic and ecological state many countries. And although about 30% of the land is still covered with trees, forest protection and work are necessary for the continued existence of mankind.

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 density 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. Maximum amount 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 areas are called natural areas boreal, temperate, subtropical, tropical, subequatorial and equatorial belt, 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 the geomorphological classification, the climate of areas with excessive moisture is considered humid, when precipitation exceeds the amount of moisture used for evaporation and infiltration into the soil, and excess moisture is removed by river runoff, which contributes to the development of erosional 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. Subequatorial plants grow in the tropical zone monsoon forests, equatorial rainforests, tropical rainforests, tropical rainforests, deciduous and semi-deciduous forests, including mangroves and savannahs.

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.

Ferralitic soils are common in South and Central America, Central Africa, South and Southeast Asia, 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.

Forest zones of the temperate zones of the Northern and Southern hemispheres include the taiga zone, the zone of mixed forests, the zone of deciduous forests and monsoon forests temperate zone.

characteristic feature forest zones temperate zones is seasonal 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 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 accounts for 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 humid 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 zones equatorial forests there is almost no seasonal rhythm of natural processes, moisture is abundant, temperatures are constantly high, rivers are high-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. a tropical forest. 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 tropical belts Northern and Southern Hemispheres (South Florida, Central and South America, India, the island of Madagascar, Southeast Asia, Australia, the islands of Oceania and the Malay Archipelago. They occupy mainly the windward slopes of mountain areas. The climate is tropical humid or seasonally humid with the dominance of humid oceanic trade winds.

According to the Forest Information System (FORIS) established by the FAO, out of the total area of ​​tropical forests (1756.3 million ha), lowland forests make up 88%, mountain forests - 11.6% and highland areas not occupied by tree vegetation - 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 a secondary tropical forest is considered to be depleted and rather uniform in ecological characteristics. species composition trees - edificators.

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

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 over 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.