All cultural phytocenoses, especially monocultures, are rather unstable groups that require constant human care. In addition, wood is a valuable raw material, the demand for which is constantly growing. Therefore, optimizing the amount of forest land is an important environmental and economic task. It is ensured through logging and restoration forest plantations. There has always been a shortage of wood in Ukraine, so the creation of forest crops is a necessary economic and environmental event. The rate of restoration of forest cover in the second half of the 20th century was quite significant (Fig. 10.3). But, despite all efforts, the forest cover of our state remains far from optimal (Fig. 10.4). It is uneven across regions. The number of areas covered with forests in the Carpathians and Polesie is as close as possible to the optimal one. In other regions, the proportion of forested areas is much smaller. Unfortunately, Ukraine remains one of the least forested countries in Europe (Table 10.3). There are both objective and subjective reasons for this. On the one hand, in our state, significant areas are occupied by agricultural land, and on the other, the use of land is still far from efficient.
Rice. 10.3. Dynamics of growth of areas covered with forest vegetation in Ukraine
Rice. 10.4. Forest cover of the territory of Ukraine
Table 10.3
Forest cover in European countries
|
No. |
A country |
Total area of the country, thousand hectares |
Area of forested land, thousand hectares |
Forest cover, % |
|
Finland |
||||
|
Germany |
||||
|
Norway |
Rice. 10.5. Reforestation and fellings after clear felling in forests State Committee forestry Ukraine
Felling is the main method of obtaining wood. At all cutting sites, forest crops must be created after clear felling. In modern Ukraine, preference is given to creating forest crops from the main forest-forming species (Scots pine, common oak, black alder) mixed with accompanying tree species (silver birch, aspen) and shrubs. But, in general, the rate of forest creation in Ukraine is slightly higher than the volume of felling, since more trees are planted than cut down (Fig. 10.5). This occurs due to the afforestation of areas unsuitable for growing crops, and in bad weather.
Tree cutting is a powerful environmental impact. Even the destruction of one tree can lead to internal restructuring of the group. IN tree species lower tiers, due to increased insolation, there is a chance to break out into the upper tier and fulfill its natural function - to give birth to offspring. Changes should be expected in almost all tiers of the phytocenosis - from the suppression of development in shade-tolerant plants to the death of above-ground parts in shade-loving ones. In forestry practice, depending on the purpose, various fellings are used:
final fellings- this is the cutting down of mature and overripe tree stands for the purpose of timber harvesting;
intermediate fellings- this is a system of consistent measures aimed at ensuring the growth of the forest from the moment of its creation to the age of ripeness, they include the gradual removal of part of the trees that are undesirable in the forest stand;
sanitary fellings- removal from tree stands of trees that are drying out, withered, stormy, damaged by pests and diseases.
According to their own environmental consequences The most significant are the final fellings. They lead to fundamental changes in phytocenoses. To understand the impact on phytocenosis, it is necessary to distinguish between different types of felling forests, since their results will largely depend on this:
solid cuttings, at in which all layers of woody vegetation and shrubs are cut:
selective or gradual, in which only part of the tree layer is cut off.
Depending on the areas where clear felling is carried out, there are sucilnolisosichii And concentrated cuttings. Sucillin fox logging is carried out in relatively small areas, and concentrated logging is carried out in areas of more than 50 hectares with a cutting area width of more than 250 m. Of course, the consequences of cutting down large areas will be even more radical and even catastrophic for specific plant species and their communities. Forest felling is carried out at certain optimal times, depending on the purpose, and forest areas (cutting areas) where tree felling will be carried out are allocated in advance.
A cutting area is a section of forest allocated for main and intermediate felling (with the exception of clear sanitary oaks), as well as the area where said cuttings are carried out.
After clear cutting, cutting areas can be left for natural restoration or cultivation with those tree species that meet environmental conditions and have economic importance. When focusing on natural recovery, we take into account environmental conditions in a specific area, changes in the composition of the phytocenosis and economic benefits from the potential tree stand are possible. After clear felling, a change in the species composition of forest stands almost always occurs, so the effectiveness of natural restoration depends on the type of forest conditions. In the Carpathians, beech is restored quite well naturally in its altitudinal zone near Buchin. In Polesie, in order to obtain valuable pine or oak stands in place of felled ones, special forestry measures are required to ensure the natural regeneration of these species.
Gradual and selective felling is aimed at maximizing the preservation of biological diversity and creating conditions for the restoration of indigenous forest phytocenoses. their effectiveness increases when carrying out activities aimed at increasing the yield of seeds of the species that need to be restored, and creating conditions for its rooting and further development. But gradual and selective final felling can be carried out in all types of forest conditions.
When clear cutting is carried out, the following changes are observed in a certain area:
All tree and shrub vegetation is destroyed;
Part is destroyed herbaceous plants, shrubs, mosses and lichens;
The integrity of the soil cover is compromised:
Due to the increase in direct insolation, Tino-loving and shade-tolerant species continue to die or sharply reduce their distribution;
There is an intensification of the forest litter schedule;
Hydrological growth conditions change;
Grains, weeds, and light-loving species spread over the area, which leads to the formation of sod;
Pioneer tree species appear;
Intensive vegetative regeneration of deciduous trees occurs.
Depending on the region, other specific changes in forest ecosystems may occur during logging, both immediately after logging and during succession in the area where it is carried out. Deforestation, for example, mountainous area causes water erosion of soils (washing off the pound and destroying the pedestal), which makes forest restoration impossible. In such conditions, a huge period of time is needed to restore the forest to rocks, starting with the colonization of rocks by lichens. There are many examples on Earth of the destruction of forests in mountainous areas. Now they are trying to take these features into account. Thus, the rules for final felling in the mountain forests of the Carpathians assume such an organization of forest cuttings that ensures the preservation of the water-protective, water-regulating and soil-protective properties of the forest, would prevent erosion processes on mountain slopes, promoting forest restoration in cutting areas. On slopes with a steepness of up to 25°, it is recommended to carry out gradual felling, and on slopes from 26 to 40° - only selective felling.
Quite often, after clear cuttings, forest crops were created from tree species that were unusual for the given growth conditions or for the mountain belt. At the same time, the ecological and biological properties of trees were not taken into account, and the main criterion was the demand for wood. This led to negative consequences. Thus, in Transcarpathia and the Carpathians, over the course of several centuries, there was a gradual replacement of beech plantations with spruce, due to the demand for the latter’s wood. Studies carried out in Transcarpathia on light brown mountain-forest unsaturated soils have found that replacing boots with spruce and fir leads to a decrease in the average annual moisture reserves in the soil by 8-10%. This happens:
More intense leaching of silt throughout the entire soil profile and slight accumulation in the illuvial horizon, which leads to rich soil;
Compaction of the soil surface, reduction of its water permeability, which leads to an increase in surface runoff during snowmelt and rainfall;
A decrease in total humidity and moisture reserves in the soil during the year simultaneously with an increase in dynamic moisture.
The researchers came to the conclusion that it was inappropriate to create spruce plantations in the bushes, and the created spruce plantations turned out to be unstable.
In the absence of appropriate measures, after clear cutting, one phytocenosis may be replaced by another. In Podolia, Ukraine, in cutting areas that are not cultivated with oak, the replacement of ordinary oak with common hornbeam is observed. (Carpinus betulus). Numerous hornbeam ladders appear under the canopy of oak plantations and in cutting areas - sometimes up to 500 thousand pieces per 1 hectare. The dense canopy of the hornbeam does not allow other tree species to recover. This change in species is due to the fact that oak less often produces a good harvest of acorns, while hornbeam, on the contrary, is more productive and more often produces good harvests seeds In addition, hornbeam recovers very well from stumps. In the north of Russia, changes in vegetation are quite often observed after clear cutting of spruce and spruce-fir plantations. These plantings are characterized by the fact that they are highly dense and create a specific internal environment in which the emergence of seedlings of other species is impossible. First, depending on the richness of the soil, herbaceous plants - fireweed - grow intensively in the cutting area (Chamaerion angustifolium), stinging nettle ( Urtica dioica), Langsdorff's reed grass ( Calamagrostis langsdorfii) and forest reed grass (S. arundinacea). Simultaneously with the spread of light-loving herbaceous plants, spruce undergrowth and shade-loving plants die. The next stage of overgrowing of the cutting area is the appearance and spread of shrubs, under the protection of which tree species begin to develop. The environment at the cutting site is unfavorable for the restoration of spruce (a shade-tolerant species), but the seeds of aspen, birch, and willows are easily carried by the wind in the surrounding plantings. The undergrowth of these tree species closes quite quickly and forms a tent, under which shade-tolerant and shade-loving species are restored. In the future, spruce undergrowth may appear under the canopy of birch and aspen. The latter is more durable than those indicated hardwoods and, after their death, the spruce again has the opportunity to create a spruce stand (Fig. 10.6).
Overgrowing of felling areas after felling depends on vegetation cover was before the start of logging. For the European North of Russia, types of cutting areas have been developed, which are created after clear cutting of plantations in certain types of forest (Fig. 10.7).
Rice. 10.6. Dynamics of changes in height of spruce and birch during joint growth
Rice. 10.7. Formation of types of cutting areas depending on forest types in the north of the European part of Russia
(According to I. S. Melekhov, 1959)
Plants-indicators of cutting sites are those indicators that are directly or indirectly related to the past type of forest. One or more types of cutting areas may be formed in one type of forest. This makes it possible to predict possible changes in vegetation after clear-cutting in a specific forest type and plan appropriate forestry activities for reforestation
Economic activities related to logging were not always accompanied by measures to restore and preserve forests. In the history of mankind there are many examples of the destruction of forests and the gradual degradation of territories to a state that makes it impossible to use them for the growth of tree species. In ancient times, evergreens were common in the Mediterranean oak forests. they were cut down mainly for fuel. From the stumps that remained, shoots sprang up, which created low-stemmed forests - maquis. Maquis is the first stage of degradation of the primary forest. Its height did not exceed 4 m. A herbaceous cover of cereals and herbs developed in the cutting areas. The livestock, mainly goats, that grazed here destroyed the grass and tree growth, exposing the soil. Agricultural plants began to be grown in some areas, ruining the top layer of soil. The exposure and plowing of soils contributed to wind erosion. Periodic rains completed the job - they washed away the rich soil horizons to the parent rock. Thus, over the course of several centuries, large areas of the Mediterranean turned into rocky deserts. Now only in historical monuments The evidence remains that the present-day Sahara Desert was the main grain-growing area for the Roman Empire.
IN scientific literature Often there is a description of the role of forests and 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 organic matter planets. What do they have great importance for photosynthesis, for the normal course of processes of stabilizing the oxygen balance of the atmosphere, absorption carbon dioxide, as well as to preserve soil fertility and water purity. That they are the largest repositories of the gene pool of the biosphere, a habitat for a large number of plants and animals, an important source of wood, food, feed, technical, medicinal and other resources. In addition to all this, forests absorb noise and many air pollutants, thereby favorably influencing the quality of the natural environment, and indirectly the mood of people who find positive emotions in communication with nature. In short, the economic, environmental, and aesthetic significance of forests is always highly valued.
For quantification world forest resources as an important component biological resources sushi, various indicators are used. The most important among them are indicators forest area, forest cover(proportion of forest area in the entire territory) and standing timber stock. However, when getting to know them, a rather significant difference in assessments attracts attention. If you try to compare the estimates of FAO, other international organizations and individual specialists in this field, then such a difference will be revealed quite easily. For example, in different sources 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 differences in the indicators of forest cover on the earth's land (37%, 32, 30, 27%, etc.), as well as in indicators of wood 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 forest land, which, in addition to forest land itself, also includes shrubs, open areas, clearings, burnt areas, etc. The average ones correspond to a more strict approach to the definition of forest land, the lower ones - to forested land, i.e. . areas directly occupied by forests, 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 take into account primary and secondary forests.
Table 28 gives an idea of regional differences in the distribution of the world's forest resources.
The following conclusions follow from the data presented in Table 28. Firstly, 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 echelon” according to these indicators. Thirdly, that foreign Asia, characterized by high overall indicators, has - as one might expect - the lowest provision of forest resources per inhabitant. And fourthly, that for all the main indicators included in the table, foreign Europe and Australia with Oceania close the ranking of large regions.
Table 28
DISTRIBUTION OF THE WORLD'S FOREST RESOURCES AMONG LARGE REGIONS
* Without CIS countries.
Along with the distribution of the world's forest resources across large regions of the world, their distribution across the main forest belts is also of great interest (Fig. 24). Figure 24 clearly shows the distribution coniferous forests cold zone (or coniferous boreal forests), stretching in a wide strip across the northern parts of Eurasia and North America. The belt extends to the south mixed forests temperate zone. Forests of dry areas are most characteristic of Africa (where they are represented by sparse forests and shrubs of the savannah zone), but are also found in North and South America and Australia. Equatorial rain forests grow in the belt with constant 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 rain forests are generally much less well preserved and should be sought only in isolated areas of Central and South America, Africa and South Asia. Finally, warm temperate rainforests occur in isolated, fairly large areas in North and South America, East Asia, and Australia.
Rice. 24. Schematic map of the world’s forests (according to I. S. Malakhov): 1 – coniferous forests of the cold zone; 2 – mixed forests of the temperate zone; 3 – forests of dry areas; 4 – equatorial rain forests; 5 – tropical rainforests; 6 – moist forests of the warm temperate zone
Figure 24 also provides the basis for a more generalized approach to identifying forest belts, which is more often used in educational literature. It consists of combining them into two main forest belts of the Earth– northern and southern, which are separated by a wide belt of arid territories.
Square northern forest belt– 2 billion hectares (including 1.6 billion hectares under a closed tree stand and 0.4 billion hectares under shrubs and open forests). The largest forest areas in this belt are located within Russia, Canada, and the USA. Coniferous trees occupy 67% of the total forest area, and deciduous trees - 33%. The diversity of species in the forests of the northern zone is not so great: for example, in overseas Europe there are approximately 250 species of trees and shrubs. Wood growth also occurs rather slowly. So, in coniferous forests In Russia, on average, 1.3 m 3 grows per 1 hectare per year, in Finland - 2.3 m 3, in the USA - 3.1 m 3. In the mixed forest zone this increase is noticeably greater.
Square southern forest belt– also approximately 2 billion hectares, but 97% of it consists of broad-leaved forests. At the same time, half of the entire forest area is occupied by tall-stemmed forest, and the rest is accounted for by low-density sparse forest, shrubs, and forest fallow. In the southern forest belt, the tree stand is much more diverse than in the northern: in all tropical forests On 1 hectare you can find more than 100 and even 200 different species of trees. The average annual growth of wood per 1 hectare here is several times greater than in the forests of the northern zone. And the average stock of standing timber reaches 250 m 3 /ha, which is tens of times higher than the stock in some types of forests in the northern zone. Therefore, the total supply of wood in the forests of the southern belt is greater.
Naturally, countries with the most large sizes forest areas must be searched within either the northern or southern forest belts (Fig. 25). These same belts also include countries with the most high forest cover: in the northern zone these are primarily Finland and Sweden, and in the southern zone - Suriname and Guyana in Latin America, Gabon and the Democratic Republic of the Congo in Africa, Papua New Guinea in Oceania.
Russia is the richest country in forest resources in the world. 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 timber reserves in Russian forests - 82 billion m3 - exceed the reserves 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 m3), it is second only to Canada. However, Russia's forest resources are distributed very unevenly across 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
“Natural resources” - Classification of natural resources (according to degree of depletion). Causes of desertification. State of flora and fauna. 2. Protection individual species– Red Book (since 1966). Inexhaustible. Solar energy, wind energy, tides, water, air. 1859 24 rabbits were brought from England to Australia. Oil and petroleum products.
“Fundamentals of environmental management” - Environmental management. Section 4. Bodies government controlled environmental management. Educational and methodological support of the course. Course content. Course objective: Section 8. Ecological and economic regulation of environmental management in international level. Methodological materials. Section 1. Methodological and organizational-legal management systems.
“Human influence on the world” - Human influence on plant and animal world. Powerful modern technology. Once scientists tried to estimate losses in biological diversity. In two last decades 20th century The area of forests on the planet has decreased. A reasonable man. Developing civilization, man clears forests and plows up steppes. Species that have not yet disappeared.
“Structure of the biosphere” - Using the textbook text, fill in the tables (p. 218). Structure of the biosphere. The activity of living organisms serves as the basis for the cycle of substances in nature: Contents: Test yourself: What organisms absorb carbon dioxide from the atmosphere? ? Plants? Animals How does fixed carbon return to the atmosphere? ? Do organisms breathe? Minerals are destroyed. What do microorganisms do? ? Do they fix nitrogen? Carry out oxidation and reduction reactions.
"Biological Resources" - Black Crane. Pastures for deer. Use of wood resources. Commercial and hunting resources. Feed. Lynx. Wood, particle boards. Kalina. Biological resources. From one hectare of forest you can collect: Boletus. Telegraph poles. Box containers. Test. Dandelion. Spruce. Mushrooms. Wild duck.
“Biological Resources of Russia” - In most reservoirs, the reserves of small-sized fish are not fully exploited, while the production of the most valuable species is several times higher than the allowable catch. That. foreign trade has a great influence species composition catch, degree of processing and quality of goods, as well as geography of export-import operations.
The topography of Europe is dominated by lowlands and hills; mountains here occupy less than a fifth of the territory. Average absolute altitude- about 300 m, which corresponds to elevation. Europe is three times lower than Asia; of the parts of the world lower than Europe, only Australia. The peculiar core of the relief of Eastern and, partly, Central Europe is the East European Plain.
The south of Central Europe is characterized by middle mountains. In Western Europe, the relief is contrasting - plains and mountains occupy approximately the same area. Average and high mountains characteristic of Southern Europe, the Alps stretch here.
Apennines, Pyrenees and Balkan mountains
The Apennines, Pyrenees and Balkan Mountains, nature has “allocated” about a quarter of the territory here to the plains. In Northern Europe there are the old Scandinavian mountains (Norway, Sweden), flat territories (Denmark, Finland), and in Iceland truly “ice and fire come together”, there are more than two hundred volcanoes, and a tenth of the territory is occupied by glaciers.
The main part of Europe is located within temperate latitudes. Only its extreme northern and southern regions extend into the subarctic and subtropical zones. Some islands are located in the kingdom of eternal frost - in the Arctic. In the far north, the Arctic Circle “enters” the territory of Europe; beyond this “border of the polar night” there are areas with quite severe conditions for this part of the world. climatic conditions. Average January temperatures: from -24 °C on the Arctic islands to +12 °C in Southern Europe, June: from +3 to +29 °C. Precipitation ranges from 200 mm per year to 1,500-2,000 mm in the mountains, and the aridity of the climate increases from the northwest to the south and southeast.
Part of Southern Europe
Part of Southern Europe is located in the subtropical zone, the temperature here rarely drops below zero degrees, so the local climate is considered the most favorable not only for agricultural crops, but also for humans. It is no coincidence that history decreed that the two greatest states of antiquity appeared here - Ancient Greece And Ancient Rome. In Northern Europe and large parts of Eastern Europe, nature is more severe. Summer temperatures here range from +12 to +18 °C, and winter temperatures from 0 to -10 °C; in the north of Eastern Europe the thermometer drops even lower. Big influence The North Atlantic Current influences the formation of the nature of the western and northwestern parts of Europe and economic activity in these areas. Thanks to it, the air temperature rises and the amount of precipitation increases.
Total land area of Europe
The total area of Europe's land fund is about 10 million km2, or 1,000 million hectares (excluding islands). Each European has approximately 1.5 hectares of land, which is significantly more than in Asia, but much less than in North America. Best endowed land resources certain regions of Russia.
About half of the land is agricultural land. The forest cover of Europe exceeds 30%, and it is especially high in its northern part. Russia has the best stock of timber; about 70% is concentrated here, as well as in Northern Europe. forest resources Europe. Maximum indicator forest cover in Finland, where forests occupy 77% of the territory. Despite the deforestation, the area European forests has stabilized.
In Europe, there is a natural decrease in river flow from west to east and from north to south. Nature has generously distributed rivers across Northern and Central Europe, as well as certain areas of Eastern Europe. The river network of the southern part of Europe is insufficiently developed, and in summer some of the rivers here become shallow and even dry up. Lakes are also unevenly distributed across Europe; there are especially many of these natural reservoirs in Northern Europe and northern Russia. Many of them owe their appearance to the ancient glacier that advanced on Europe millions of years ago. Largest lakes: Ladoga, Onega, Balaton, Geneva.
Mineral resources of Europe
Europe's mineral resources are quite diverse, but are largely depleted, especially in the western part. In addition, to “feed” the powerful economy of the region, its own reserves are not enough.
Europe is home to more than 700 million inhabitants. The average population density is 32 people/km2 (the region includes Russia with an average density throughout the country of 8 people/km2). But the differences in the population of individual regions are very significant, primarily between the Scandinavian countries, Russia and the rest
Europe (especially central part Western Europe, where there are countries with a density of 300 people/km2 or more), the eastern and Northern part Europe, the highest density is in the southern and western parts.
Europe's urbanization rate is one of the highest in the world, with 70.3% of the population living in cities. The highest proportion of urban population is in the central part of Western Europe; the level of urbanization is relatively low in southern Europe. So in Albania, Bosnia and Herzegovina, Portugal, the Republic of Serbia and Montenegro, Slovenia it ranges from 44% to 55%. TO largest cities of the world include (including suburbs) Moscow and Paris.
The scientific literature often describes the role of forests and 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 planet’s organic matter accumulates. That they are of great importance for photosynthesis, for the normal course of 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 of plants and animals, an important source of wood, food, feed, technical, medicinal and other resources. In addition to all this, forests absorb noise and many air pollutants, thereby beneficially affecting the quality of the environment. natural environment, and indirectly on the mood of people who find positive emotions in communication with nature. In short, the economic, environmental, and aesthetic significance of forests is always highly valued.
Various indicators are used to quantify the world's forest resources as an important component of terrestrial biological resources. The most important among them are indicators forest area, forest cover(proportion of forest area in the entire territory) and standing timber stock. However, when getting to know them, a rather significant difference in assessments attracts attention. If you try to compare the estimates of FAO, other international organizations and individual specialists in this field, then such a difference will be revealed quite easily. For example, various sources estimate the global forest area at 51.2 billion hectares; 43.2; 39.6; 36.0; 34.4;
30.0 billion hectares. Accordingly, there are also large differences in the indicators of forest cover on the earth's land (37%, 32, 30, 27%, etc.), as well as in indicators of wood 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 forest land, which, in addition to forest land itself, also includes shrubs, open areas, clearings, burnt areas, etc. The average ones correspond to a more strict approach to the definition of forest land, the lower ones - to forested land, i.e. . areas directly occupied by forests, 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 take into account primary and secondary forests.
Table 28 gives an idea of regional differences in the distribution of the world's forest resources.
The following conclusions follow from the data presented in Table 28. Firstly, 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 echelon” according to these indicators. Thirdly, that foreign Asia, which is distinguished by high overall indicators, has - as one might expect - the lowest provision of forest resources per capita. And fourthly, that for all the main indicators included in the table, foreign Europe and Australia with Oceania close the ranking of large regions.
Table 28
DISTRIBUTION OF THE WORLD'S FOREST RESOURCES AMONG LARGE REGIONS
* Without CIS countries.
Along with the distribution of the world's forest resources across large regions of the world, their distribution across the main forest belts is also of great interest (Fig. 24). Figure 24 clearly shows the distribution of coniferous forests of the cold zone (or coniferous boreal forests), stretching in a wide strip across the northern parts of Eurasia and North America. To the south lies a belt of mixed temperate forests. Forests of dry areas are most characteristic of Africa (where they are represented by sparse forests and shrubs of the savannah zone), but are also found in North and South America and Australia. Equatorial rain forests grow in a belt of consistently 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 South and Southeast Asia. Tropical rain forests are generally much less well preserved and should be sought only in isolated areas of Central and South America, Africa and South Asia. Finally, warm temperate rainforests occur in isolated, fairly large areas in North and South America, East Asia, and Australia.
Rice. 24. Schematic map of the world’s forests (according to I. S. Malakhov): 1 – coniferous forests of the cold zone; 2 – mixed forests of the temperate zone; 3 – forests of dry areas; 4 – equatorial rain forests; 5 – tropical rainforests; 6 – moist forests of the warm temperate zone
Figure 24 also provides the basis for a more generalized approach to identifying forest belts, which is more often used in educational literature. It consists of combining them into two main forest belts of the Earth– northern and southern, which are separated by a wide belt of arid territories.
Square northern forest belt– 2 billion hectares (including 1.6 billion hectares under a closed tree stand and 0.4 billion hectares under shrubs and open forests). The largest forest areas in this belt are located within Russia, Canada, and the USA. Coniferous trees occupy 67% of the total forest area, and deciduous trees - 33%. The diversity of species in the forests of the northern zone is not so great: for example, in foreign Europe there are approximately 250 species of trees and shrubs. Wood growth also occurs rather slowly. Thus, in the coniferous forests of Russia, on average, 1.3 m 3 grows per 1 hectare per year, in Finland - 2.3 m 3, in the USA - 3.1 m 3. In the mixed forest zone this increase is noticeably greater.
Square southern forest belt– also approximately 2 billion hectares, but 97% of it consists of broad-leaved forests. At the same time, half of the entire forest area is occupied by tall-stemmed forest, and the rest is accounted for by low-density sparse forest, shrubs, and forest fallow. In the southern forest belt, the tree stand is much more diverse than in the northern: in all tropical forests per 1 hectare you can find more than 100 and even 200 various types trees. The average annual growth of wood per 1 hectare here is several times greater than in the forests of the northern zone. And the average stock of standing timber reaches 250 m 3 /ha, which is tens of times higher than the stock in some types of forests in the northern zone. Therefore, the total supply of wood in the forests of the southern belt is greater.
Naturally, countries with the largest forest areas should be sought within either the northern or southern forest belts (Fig. 25). These same belts also include countries with the highest forest cover: in the northern belt these are primarily Finland and Sweden, and in the southern belt - Suriname and Guyana in Latin America, Gabon and the Democratic Republic of the Congo in Africa, Papua New Guinea in Oceania.
Russia is the richest country in forest resources in the world. 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 timber reserves in Russian forests—82 billion m3—exceed those of any major 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 m3), it is second only to Canada. However, Russia's forest resources are distributed very unevenly across 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
26. Problems of deforestation
Deforestation(deforestation) is the loss of forest due to natural causes or as a result of economic activity person.
The process of anthropogenic deforestation actually began 10 thousand years ago, during the era of the Neolithic revolution and the emergence of agriculture and cattle breeding, and continues to this day. According to existing estimates, during the era of this revolution, 62 billion hectares (62 million km 2) of the earth's land were covered with forests, and taking into account shrubs and coppice - 75 billion hectares, or 56% of its entire surface. If we compare the second of these figures with the modern one, which was given above, it is not difficult to conclude that the forest cover of the land during the formation and development of human civilization has decreased by half. A spatial reflection of this process is shown in Figure 26.
This process took place in a certain and understandable geographical sequence. Thus, forests were first cleared in the areas of the ancient river civilizations of Western Asia, India, Eastern China, and in the era of ancient civilization - in the Mediterranean. In the Middle Ages, widespread deforestation began in foreign Europe, where until the 7th century. they occupied 70–80% of the entire territory, also on the Russian Plain. In the 17th–19th centuries, with the beginning of industrial revolutions, active industrial and urban development, as well as with the further development of agriculture and livestock raising, the process of deforestation most affected Europe and North America, although it also affected some other regions of the world. As a result, only in 1850–1980. The area of forests on Earth has decreased by another 15%.
Rice. 26. Change in the area covered by forest vegetation during the existence of civilization (according to K. S. Losev)
Deforestation continues at a rapid pace today: annually it occurs on an area of approximately 13 million hectares (these figures are comparable to the size of entire countries, for example Lebanon or Jamaica). The main reasons for deforestation remain the same. This is the need to increase agricultural land and areas intended for industrial, urban and transport development. it's the same constant growth needs for commercial and firewood (about 1/2 of all wood produced in the world is used for fuel). That is why the volume of timber harvesting is increasing all the time. Thus, in 1985, its global indicator was approximately 3 billion m 3, and by 2000 it increased to 4.5–5 billion m 3, which is comparable to the entire annual increase in wood in the world's forests. But we must also remember the damage that fires cause to forest vegetation, acid rain and other negative consequences of human activity.
However, it must be taken into account that the geographical distribution of deforestation has undergone significant changes in recent decades. Its epicenter moved from the northern to the southern forest belt.
Economically developed countries, located within the northern forest belt, thanks to rational forestry management, the situation as a whole can be assessed as relatively prosperous. Forest areas in this belt Lately not only do they not decrease, but even increase somewhat. This was a consequence of the implementation of a system of measures for the conservation and reproduction of forest resources. It includes not only control over the natural regeneration of forests, which is characteristic primarily of the taiga forests of North America and Eurasia, but also artificial afforestation, used in countries (primarily European) with previously cleared and unproductive forests. Nowadays, the volume of artificial reforestation in the northern forest belt already reaches 4 million hectares per year. In most countries of Europe and North America, as well as in China, timber growth exceeds annual cuttings.
This means that everything said above about increasing deforestation applies mainly to the southern forest belt, where this process takes on environmental disaster ugh. Moreover, the forests of this belt, as is well known, perform the most important function of the “lungs” of our planet and it is in them that more than half of all species of fauna and flora present on Earth are concentrated.
Rice. 27. Death tropical forests V developing countries ah in 1980–1990 (according to "Rio-92")
The total area of tropical forests by the early 1980s. still amounted to about 2 billion hectares. In America they occupied 53% of the total area, in Asia - 36, in Africa - 32%. These forests, located within more than 70 countries, are usually divided into evergreen and semi-deciduous forests of the constantly humid tropics and deciduous and semi-deciduous forests and tree-shrub formations of the seasonally humid tropics. The category of tropical rainforests includes approximately 2/3 of all tropical forests in the world. Almost 3/4 of them are in just ten countries – Brazil, Indonesia, Democratic Republic Congo, Peru, Colombia, India, Bolivia, Papua New Guinea, Venezuela and Myanmar.
However, then the deforestation of the southern belt accelerated: in UN documents, the speed of this process was first estimated at 11, and then began to be estimated at 15 million hectares per year (Fig. 27). Statistics show that only in the first half of the 1990s. More than 65 million hectares of forests were cut down in the southern zone. According to some estimates, total area tropical forests have already decreased by 20–30% in recent decades. This process is most active in Central America, in the northern and southeastern parts South America, Western, Central and East Africa, in South and Southeast Asia (Fig. 28).
This geographical analysis can be taken to the level individual countries (Table 29). Following the top ten “record-breaking” countries, representing almost all the regions noted above, are Tanzania, Zambia, the Philippines, Colombia, Angola, Peru, Ecuador, Cambodia, Nicaragua, Vietnam, etc. As for the forest losses of individual countries, not expressed in absolute and in relative terms, the “leaders” here are Jamaica (7.8% of forests were cleared there per year), Bangladesh (4.1), Pakistan and Thailand (3.5), Philippines (3.4 %). But in many other countries of Central and South America, Africa, South and Southeast Asia, such losses amount to 1–3% per year. As a result, in El Salvador, Jamaica, and Haiti, almost all tropical forests have actually already been destroyed; in the Philippines, only 30% of primary forests have been preserved.
Rice. 28. Countries with the largest annual volumes of tropical forest clearing (according to T. Miller)
Can be called three main reasons leading to deforestation in the southern forest belt.
The first is to clear land for urban, transport and especially slash-and-burn agriculture, which still employs 20 million families in tropical forests and savannas. Slash-and-burn agriculture is believed to be responsible for the destruction of 75% of the forest area in Africa, 50% of the forests in Asia and 35% of the forests in Latin America.
Table 29
TOP TEN COUNTRIES BY AVERAGE ANNUAL FOREST CLEARANCE
The second reason is the use of wood as fuel. According to the UN, 70% of the population of developing countries use firewood for heating their homes and cooking. In many countries Tropical Africa, in Nepal and Haiti their share in the fuel used reaches 90%. The rise in oil prices on the world market in the 1970s. led to the fact that forests began to be cut down (primarily in Africa and South Asia) not only in the near but also in the distant surroundings of cities. In 1980, approximately 1.2 billion people in developing countries lived in areas experiencing firewood shortages, and by 2005 this number had risen to 2.4 billion.
The third reason is the increasing export of tropical wood from Asia, Africa and Latin America to Japan, Western Europe and the USA, and its use for the needs of the pulp and paper industry.
The poor, and especially the poorest developing countries, are forced to do this in order to at least slightly improve their balance of payments, burdened by debts to the rich countries of the North. Many believe that they cannot be blamed for such a policy. For example, at the opening of the IX Forestry Congress held in Paris in 1991, then-President of France François Mitterrand said: “What right do we have to reproach the population of tropical regions, for example, for contributing to the destruction of forests when they are forced to do so in order to just get by."
To prevent the complete destruction of tropical forests already in the 21st century. Urgent and effective measures are needed. Among the possible ways of reproducing forest areas in the southern zone, the greatest effect, perhaps, can be achieved by creating forest plantations specifically designed for growing highly productive and fast-growing tree species, such as eucalyptus. The existing experience in creating such plantations shows that they make it possible to grow 10 times more valuable wood than, say, European forests. At the end of the 1990s. Such plantations worldwide already occupied 4.5 million hectares, of which 2 million hectares were in Brazil.
At the World Conference on Environment and Development in Rio de Janeiro in 1992, the Statement of Principles on Forests was adopted as a special document.
Many of the problems listed above are also relevant for Russia, despite its wealth of forest resources. With a formal approach to this issue, there is no reason for any concern. Indeed, the country's estimated logging area is 540 million m3, but approximately 100 million m3 is actually cut down. However, these are average figures that do not take into account the differences between the European part of the country, where the estimated logging area is often exceeded, and the Asian part, where it is underutilized. It is necessary to take into account the significant loss of forest plantations, primarily due to forest fires(in 2006 – 15 million hectares). Therefore, Russia is taking measures for rational forest management and reproduction of forest resources. Now the area under forests is not decreasing, but growing.
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