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Desertification(desertification, progressive formation of deserts, or Sahel syndrome) is a process of land degradation in relatively dry (arid, semi-arid and arid sub-humid) areas of our planet, caused by various factors, including natural climate change and human activities. This land degradation results in the expansion or formation of deserts, or the development of environmental conditions similar to desert conditions. Moreover, the stage of steppe formation preceding desertification is called steppe formation. Currently, as a result of this process, the total area of fertile land on the planet is being reduced annually by approximately 12 million hectares, which is approximately equal to the area of arable land in Germany. At the same time, there is a tendency for the situation to further deteriorate.

Desertification can progress under the influence of wind erosion, denudation (washing out by water), salinization and decreased soil cohesion. A significant cause of desertification is human activity, i.e. desertification is largely anthropogenic in nature. However, in addition to this, natural fluctuations in precipitation volume play an important role in this process, while periods of drought can provoke or intensify the desertification process.

Desertification problem acquired more serious significance in the early 70s of the 20th century due to drought and the associated catastrophic famine in the Sahel natural zone in Africa. In 1977, in the capital of Kenya, Nairobi, as part of the first UN conference to combat desertification, it was recognized that biosphere degradation was occurring on Earth, caused by the following factors of human intervention in nature:

Eating vegetation cover by domestic animals,

Depletion of lands as a result of their overuse,

Deforestation,

Incorrect irrigation methods.

The most common type of human intervention in nature is the consumption of vegetation by domestic animals, meaning that the number of livestock per unit area of land is too large for the arid climatic conditions of the area. Therefore, due to animal grazing, the vegetation cover becomes increasingly sparse and the soil loosens. This leads to increased soil erosion, which further deteriorates the conditions for plant growth.

The next most destructive type of interference with nature is the excessive use of arable land. Reduced fallow periods, improper irrigation practices, erosion-inducing plowing of sloping land on hillsides and inappropriate crop types cause changes in the soil that reduce vegetation cover and thereby increase erosion. Soil conditions are degraded by chemicals such as fertilizers or pesticides and by mechanical compaction from agricultural machinery, which can lead to the extirpation of many soil-dwelling animal species (e.g. earthworms).

Finally, deforestation in dry areas is also a significant cause of desertification. Deforestation for arable land and the need for wood for heating and construction have led to catastrophic deforestation in many arid regions of the Earth, particularly in many densely populated regions of Africa, where wood is still the most important energy source.

However, fighting desertion is extremely difficult. Overuse of arable land and climate change may have the same effects and be interrelated, making it very difficult to determine the causes of desertification and take adequate countermeasures. In this direction, a special role is given to the study of the past (i.e., the history of desertification), since it allows us to draw a clearer boundary between natural and anthropogenic factors. At the same time, the results of recent studies of the history of desertification in Jordan call into question the effectiveness of current measures to protect vegetation and land in the face of progressive climate change and the ability of humans to change anything. For example, increasing climate warming may well lead to the extinction of artificial forests.

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

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During the plowing of fields, myriads of particles of fertile soil cover rise into the air, disperse, are carried away from the fields by streams of water, are deposited in new places, and are irretrievably carried away in huge quantities into the World Ocean. The natural process of destruction by water and wind of the top layer of soil, washing away and dispersing its particles is greatly enhanced and accelerated when the lyuli plow up too much land and do not allow the soil to “rest.”

Under the influence of living organisms, water and air, the most important ecosystem, thin and fragile, is gradually formed on the surface layers of the lithosphere - soil, which is called the “skin of the Earth”. This is the guardian of fertility and life. A handful of good soil contains millions of microorganisms that maintain fertility. It takes a century for a layer of soil 1 cm thick to form. It can be lost forever in one field season. According to geologists, before people began to engage in agricultural activities, graze livestock and plow land, rivers annually carried about 9 billion tons of soil into the World Ocean. Nowadays this amount is estimated at approximately 25 billion tons.

Soil erosion, a purely local phenomenon, has now become universal. In the United States, for example, about 44% of cultivated land is susceptible to erosion. In Russia, unique rich chernozems with a humus content of 14-16%, which were called the citadel of Russian agriculture, disappeared. In Russia, the area of the most fertile lands with a humus content of 10-13% has decreased by almost 5 times.

A particularly difficult situation arises when not only the soil layer is demolished, but also the parent rock on which it develops. Then the threshold of irreversible destruction comes, and an anthropogenic desert arises. The Shillong plateau in the Cherrapunji region, located in northeast India, presents a striking picture. This is the wettest place in the world, where on average more than 12 m of precipitation falls per year. But in the dry season, when the monsoon rains stop (October - May), the Cherrapunji region resembles a semi-desert. The soils on the slopes of the plateau have been practically washed away, exposing barren sandstones.

One of the most global and fleeting processes of our time is the expansion of desertification, the decline and, in the most extreme cases, the complete destruction of the biological potential of the Earth, which leads to conditions similar to those of a natural desert.

Natural deserts and semi-deserts occupy more than 1/3 of the earth's surface. These lands are home to about 15% of the world's population. Deserts are areas with an extremely arid continental climate, usually receiving an average of only 150-175 mm of precipitation per year. Evaporation from them is much higher than their moisture. The most extensive desert massifs are located on both sides of the equator, between 15 and 450 northern latitudes, and in Central Asia and Kazakhstan deserts reach 500 northern latitudes. Deserts are natural formations that play a certain role in the overall ecological balance of the planet’s landscapes.

As a result of human activity, by the last quarter of the 20th century. More than 9 million km2 of deserts appeared, and they already covered 43% of the total land area.

In the 90s Desertification began to threaten 3.6 million hectares of drylands. This represents 70% of potentially productive drylands, or? total land surface area, and these data do not include the area of natural deserts. About 1/6 of the world's population suffers from this process. Desertification can occur in different climatic conditions, but it occurs especially rapidly in hot, arid regions. Africa contains almost a third of all arid regions of the world; they are also widespread in Asia, Latin America and Australia. On average, 6 million hectares of cultivated land are subject to desertification per year, which are completely destroyed, and over 20 million hectares reduce their productivity. This is the speed of approaching the threshold of irreversible destruction.

Desertification and devastation can occur in any climate as a result of the destruction of the natural system. But in arid regions, drought also becomes the “engine” of desertification. Desertification, developing as a result of inept and immoderate economic activity, has more than once destroyed entire civilizations. In schools all over the world, during history lessons, children are taught that people need to know history in order to learn lessons for the future. Has humanity learned lessons from the history of the collapse of past civilizations buried under sand? The main difference between the experience of history and today is the pace and scale. Excessively active economic activity, the pressure of which had accumulated over centuries and even millennia, has now been compressed into decades. If earlier individual civilizations perished, buried by sands, now the process of desertification, originating in different places and having different regional manifestations, has assumed a global scale. The accumulation of carbon dioxide in the atmosphere, increased dust and smoke levels in the atmosphere accelerate the aridization of land. This process covers not only arid regions.

Sahel - in Arabic - coast, outskirts - this is the name of the transition zone up to 400 km wide, which extends south from the Sahara Desert to the savannahs of West Africa.

At the end of the 60s. a long-term drought broke out in this zone, which reached its climax in 1973. As a result of this drought, about 250,000 people died in the African countries of the Sahel zone - Senegal, Gambia, Mauritania, Mali, etc. There was a massive loss of livestock - and cattle breeding forms the basis of economic activity and the source of livelihood for the majority of the population in these areas. Many wells and even large rivers such as the Niger and Senegal have dried up.

Lake Chad's surface has been reduced to 1/3 its normal size. In the 80s Disasters caused by drought and desertification have become continent-wide in Africa. The consequences of these processes are experienced by 34 African countries and 150 million people. In 1985, about 1 million people died in Africa and 10 million people became “environmental refugees.” The rate of advance of desert boundaries in Africa in some places is up to 10 km per year.

The fate of forests and the history of humanity on all continents were closely interconnected. Forests served as the main source of food for primitive communities that lived by hunting and gathering. They were a source of fuel and building materials for the construction of dwellings. Forests served as a refuge for people and, to a large extent, as the basis for their economic activity. The life of forests and the life of people, the connections between them are reflected in the culture, mythology, and religion of most peoples of the world. About 10 thousand years ago, before the advent of agricultural activity, dense forests and other forested areas occupied more than 6 billion hectares of land surface. By the end During the 20th century, their area decreased by almost 1/3 and now they occupy only a little more than 4 billion hectares. In France, for example, where forests initially covered about 80% of the territory, by the end of the 20th century. their area decreased to 14%; in the USA, where forests at the beginning of the 17th century. Almost 400 million hectares were covered; by 1920, 2/3 of this forest cover was destroyed.

desertification productive land ecological

Bibliography

Encyclopedia for children: T.3 (Geography). - M., Avanta+, 1994. - 640 p.

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Desertification problem

Desertification is currently one of the most significant global problems of humanity.

Soil erosion is especially severe in the largest and most populous countries. The Yellow River in China annually carries about 2 billion soils into the World Ocean. Soil erosion not only reduces fertility and reduces crop yields. As a result of soil erosion, artificially constructed water reservoirs become silted much faster than is usually envisaged in projects, and the possibility of irrigation and obtaining electricity from hydroelectric power plants is reduced.

A particularly difficult situation arises when not only the soil layer is demolished, but also the parent rock on which it develops. Then the threshold of irreversible destruction comes, and an anthropogenic desert arises. The Shillong plateau in the Cherrapunji region, located in northeast India, presents a striking picture. This is the wettest place in the world, where on average more than 12 m of precipitation falls per year. But during the dry season, when the monsoon rains stop (October - May), the Cherrapunji region resembles a semi-desert. The soils on the slopes of the plateau have been practically washed away, exposing barren sandstones.

One of the most global and fleeting processes of our time is the expansion of desertification, the decline and, in the most extreme cases, the complete destruction of the Earth's biological potential, which leads to conditions similar to those of a natural desert.

Natural deserts and semi-deserts occupy more than 1/3 of the earth's surface. These lands are home to about 15% of the world's population. Deserts are areas with extremely arid continental climates, typically receiving an average of only 150-175 mm of precipitation per year. Evaporation from them is much higher than their moisture. The most extensive desert tracts are located on both sides of the equator, between 15 and 45 0 northern latitude, and in Central Asia and Kazakhstan deserts reach 50 0 northern latitude. Deserts are natural formations that play a certain role in the overall ecological balance of the planet’s landscapes.

As a result of human activity, by the last quarter of the 20th century. More than 9 million km2 of deserts appeared, and they already covered 43% of the total land area.

In the 90s Desertification began to threaten 3.6 million hectares of drylands. This represents 70% of the potentially productive drylands, or ½ of the total land surface area, and does not include the area of natural deserts. About 1/6 of the world's population suffers from this process. Desertification can occur in different climatic conditions, but it occurs especially rapidly in hot, arid regions. Africa contains almost a third of all arid regions of the world; they are also widespread in Asia, Latin America and Australia. On average, 6 million hectares of cultivated land are subject to desertification per year, which are completely destroyed, and over 20 million hectares reduce their productivity. This is the speed of approaching the threshold of irreversible destruction.

According to UN experts, current losses of productive land will lead to the fact that by the end of the century the world could lose almost 1/3 of its arable land. Such a loss, at a time of unprecedented population growth and increasing food demand, could be truly disastrous.

More and more people around the world are becoming environmental refugees.

The desertification process is usually caused by the combined action of nature and humans. This effect is especially destructive in arid regions with their inherent fragile, easily destroyed ecosystems. The destruction of sparse vegetation due to excessive grazing of livestock, cutting down trees and shrubs, plowing of lands unsuitable for agriculture, and other types of economic activities that disrupt the fragile balance in nature greatly increase the effect of wind erosion and drying out of the upper layers of the soil. The water balance is sharply disrupted, the groundwater level decreases, and wells dry up. The soil structure is destroyed, and their saturation with mineral salts increases. Due to excessive economic load, complexly organized river basin systems turn into primitively organized desert landscapes.

In schools all over the world, during history lessons, children are taught that people need to know history in order to learn lessons for the future. Has humanity learned lessons from the history of the collapse of past civilizations buried under sand?

Desertification of lands

The main difference between the experience of history and today is the pace and scale. Excessively active economic activity, the pressure of which had accumulated over centuries and even millennia, has now been compressed into decades. If earlier individual civilizations perished, buried by sands, now the process of desertification, originating in different places and having different regional manifestations, has assumed a global scale. The accumulation of carbon dioxide in the atmosphere, increased dust and smoke levels in the atmosphere accelerate the aridization of land. This process covers not only arid regions.

The expanding area of deserts contributes to the development of dry climatic conditions, which are likely to have a large influence on the frequency of multi-year droughts. The vicious circle closes.

Sahel - in Arabic - coast, outskirts - this is the name of the transition zone up to 400 km wide, which extends south from the Sahara Desert to the savannahs of West Africa.

At the end of the 60s. A long-term drought broke out in this zone, which reached its climax in 1973. As a result of this drought, about 250,000 people died in the African countries of the Sahel zone - Senegal, Gambia, Mauritania, Mali, etc. There was a massive loss of livestock - and cattle breeding forms the basis of economic activity and the source of livelihood for the majority of the population in these areas. Many wells and even large rivers such as the Niger and Senegal have dried up. The surface of Lake Chad has shrunk to 1/3 of its normal size. In the 80s Disasters caused by drought and desertification have become continent-wide in Africa. The consequences of these processes are experienced by 34 African countries and 150 million people. In 1985, about 1 million people died in Africa and 10 million people became “environmental refugees”. The rate of advance of desert boundaries in Africa in some places is up to 10 km per year.

The fate of forests and the history of humanity on all continents were closely interconnected. Forests served as the main source of food for primitive communities that lived by hunting and gathering. They were a source of fuel and building materials for the construction of dwellings. Forests served as a refuge for people and, to a large extent, as the basis for their economic activity. The life of forests and the life of people, the connections between them are reflected in the culture, mythology, and religion of most peoples of the world. About 10 thousand years ago, before the advent of agricultural activity, dense forests and other forested areas occupied more than 6 billion hectares of land surface. By the end of the 20th century, their area decreased by almost 1/3 and now they occupy only a little more than 4 billion hectares. In France, for example, where forests initially covered about 80% of the territory, by the end of the 20th century. their area decreased to 14%; in the USA, where forests at the beginning of the 17th century. Almost 400 million hectares were covered; by 1920, 2/3 of this forest cover was destroyed.

All the aspects considered do not have the best effect not only on our general well-being, but, mainly, on the well-being of our children and descendants in general. Therefore, we must provide them with a glorious and cloudless future: develop and implement projects to limit and eradicate such undesirable processes in general.

Bibliography:

Encyclopedia for children: T. 3 (Geography). – M., Avanta+, 1994. – 640 p.

Desertification. The nature of desertification. Desertification degree. Depth and speed of desertification.

Desertification is a process that leads to the loss of continuous vegetation cover by a natural ecosystem with the further impossibility of its restoration without human intervention. There are two forms of desertification: 1. expansion of the desert area, 2. deepening of the process of desertification in place.

Drought in general is a natural crisis that occurs periodically in many parts of the globe. She is a frequent visitor to countries located near the southern borders of the Sahara. Today, lands in the southwest of America, as well as certain areas of Bolivia, Australia and Brazil, are undergoing desertification. The problem of desertification and drought also exists in Russia. One of the main causes of desertification is the grazing of more cattle than the pasture can support. The second cause of desertification is intensive agriculture on the not very fertile lands of the arid zone. The process of desertification is intensifying due to the fact that people, whose numbers are increasing, are cutting down entire forests for firewood. The spread of desertification is also influenced by political and social factors. All these consequences of human activity - overgrazing, excessive timber consumption, intensive agriculture combined with erosion, urbanization of arid regions, salinization and overdrafting of groundwater - are the result, at least in part, of pressure on the nature of human populations.

Desertification is the process of degradation of all natural life support systems: in order to survive, the local population must either receive outside help or leave in search of land suitable for life. More and more people around the world are becoming environmental refugees. The expanding area of deserts contributes to the development of dry climatic conditions, which are likely to have a large influence on the frequency of multi-year droughts. The vicious circle closes.

The International Convention to Combat Desertification is one of the main mechanisms for the participation of all countries of the world in solving this problem. Its main focus is on improving soil fertility and restoration, as well as protecting and rationally using land and water resources.

Desertification. Causes.

To reduce desertification processes it is necessary: 1. Limiting agricultural activities and grazing. 2.Agroforestry is the integrated activity of raising livestock or cultivating land and simultaneously growing woody plants on the same area. 3.Need for suitable technologies.

Scientists distinguish four degrees of desertification: weak, moderate, strong and very strong. Severe desertification has become widespread in Asia, Africa, North and South America, and Australia. Restoring lands affected by severe desertification requires large investments and a long time. And very severe desertification entails complete and irreversible degradation of the land. Nevertheless, about 80 million people live in areas of severe and very severe desertification. As a result of all these processes, the “load” on the land is constantly increasing, and the availability of land resources is decreasing.

The desertification process occurs at a speed of 7 km2/h.

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Desertification and its monitoring

Desertification

Desertification- the process of transformation (transition) of cultivated fertile irrigated lands into waterless and lifeless deserts with loss of soil fertility and vegetation.

Causes of desertification

Water shortage— lack of water resources to satisfy the biological needs of crops and other types of vegetation for their normal growth and development, as well as environmental requirements to stabilize the development of environmental processes.

Drought- a long period of time of year with insufficient precipitation at elevated air temperatures.

Climate aridization— increased climate aridity due to increased air temperature, evaporation and decreased precipitation, i.e. increasing the air humidity deficit according to Torveit and reducing the humidity coefficient.

Deforestation— denudation of the area of growth and development of forest plantations, which led to disruption of snow retention, accumulation of moisture reserves from rainwater. In addition, due to deforestation, soil erosion occurs on mountain slopes and foothill plains in the form of washout and erosion, as well as gully formation.

Livestock herding— denudation or thinning of pasture areas from vegetation due to an increase in the number of livestock heads compared to the standard. Denudation or thinning of pasture areas leads to a sharp decrease in soil moisture reserves formed under the influence of scanty atmospheric precipitation in the desert.

Biological death— necrosis of the plant world due to a sharp disruption of their need for water and an increase in harmful toxic substances in the soil and atmosphere.

Lack of drainage- lack of groundwater outflow in the natural-historical development of the territory and general drainage flow during artificial drainage to prevent the rise of groundwater and, as its consequences, flooding and secondary salinization in the process of irrigation and land development.

Salt accumulation under the influence of pressure groundwater. Accumulation in the root layer or aeration zone (the layer located between the surface of the earth and the groundwater level) due to their transfer by underground tributaries, formed both outside the irrigated areas and in them, as a result of which pressure complexes of aquifers are created in the absence or insufficient natural drainage. Under these conditions, piezometric pressures in aquifers represented by highly permeable soils (sands, gravel deposits, pebbles, etc.) are established above the groundwater level, creating a certain flow of water and salts into the upper weakly permeable fine earth - the aeration zone. The amount of salt accumulation depends on the intensity of the flow of pressure waters, the reserves of salts in low-permeable cover fine soils and the mineralization of underground pressure waters. In the territory represented by pressure groundwater, a surface salt profile is formed with the distribution of salt reserves in the aeration zone (above groundwater) due to their removal from the lower layers. An example of the formation of such a distribution of the salt profile is the territory of the Fergana Valley, the old irrigation zone of the Hungry Steppe of the Republic of Uzbekistan, and the Vakhsh Valley of the Republic of Tajikistan.

Salt accumulation in irrigation fields under the influence of salt imbalance. This type of salt accumulation in irrigation fields is formed in conditions when the incoming part of the water-salt balance of the field is formed due to water supply for irrigation of crops, filtration from on-farm field canals, influx from groundwater above the outgoing part (evapotranspiration, flow from the aeration zone into groundwater, groundwater reserves in lower aquifers and drainage flow) with insufficient natural and artificial drainage.

Salt accumulation under the influence of influx from higher lands. This type of salt accumulation is formed due to the transport of salts by groundwater in the areas of interconal depressions, the end parts of alluvial fans and the peripheral part of the proluvial slopes of the foothill plains, which are a zone of groundwater discharge. The intensity of salt accumulation depends on the salinity of rocks and soils hypsometrically located above the territories and the degree of mineralization of groundwater transiting into the lower irrigated areas. This type of salt accumulation is characteristic of large depressions (depressions) located in the plains.

Salt accumulation under the influence of technogenic disturbances. Salt accumulation is formed due to the release of waste from large mines, plants and factories, where residual products are discharged into water sources without treatment - into ravines and sewers.

Salt accumulation under the influence of aeolian transport. This type of accumulation is formed by the transport of weathered rock products and salts under the influence of wind-driven climate action. The source of supply of salts can be, along with weathered rock products, individual highly saline parts of deserts, semi-deserts, dried sea bottoms and saline lands located inside the irrigated area.

Decrease in groundwater level. Reduction of groundwater levels against their optimal depths and regime due to the depletion of groundwater reserves and drainage of the bottom of seas and reservoirs. An example is the dried bottom of the Aral Sea, formed under the influence of insufficient supply of surface runoff along the Syrdarya and Amu Darya rivers.

Stopping irrigation. Irrigation is stopped due to a lack of water resources and the unprofitability of agricultural production on low-fertility lands included in the irrigated fund.

Violation of the water balance of the reservoir. Violation of the water balance of water bodies most often occurs due to a shortage of water resources in the region, used mainly for the development of agricultural production, industry, public utilities and fisheries. Due to the shortage of water resources within the Aral Sea basin, more than 200-250 small and medium-sized lakes and reservoirs were drained.

Loss of fertility. Most often it occurs due to irrational and improper management of agricultural crops due to severe salinization and flooding of land with poor drainage of the territory. Desertification under the influence of loss of fertility of irrigated lands is most characteristic of irrigated lands located in river delta regions.

Types of desertification

Soil salinization. Saline soil is non-alkaline soil that contains soluble salts in large quantities that inhibit the growth of most crops. There are:

Primary soil salinization is the natural accumulation of salts in the soil due to evaporation of groundwater, salinity of parent rocks, or under the influence of aeolian, biogenic or other factors.
Secondary soil salinization is the accumulation of salts in the soil, which occurs as a result of artificial changes in the water regime, for example, due to improper irrigation. Secondary soil salinization can occur in non-saline or primary saline soils.
In most cases, secondary salinization is caused by the movement of water-soluble salts from deep layers of underlying rocks and groundwater to the surface, or by the influx of mineralized water from higher-lying irrigated areas.

Deforestation (deforestation)- reduction or destruction of the geographical landscape consisting of a set of woody, shrubby, herbaceous plants caused by changes in their living conditions or economic activities.

Land (and pasture) degradation— deterioration of the properties, fertility and productivity of land as a result of economic activity.

The reasons for land degradation in the Aral Sea basin are: long-term droughts, inefficient use of water for irrigation, leading to soil salinization, excessive grazing of livestock, which reduces and deteriorates the soil layer (blowing out the humus horizon), unjustified use of chemicals that cause soil and water pollution.

Draining the bottom of the sea and reservoirs— exposure of the seabed and reservoirs as a result of a drop in water level and a decrease in water area due to the depletion of natural restoration resources and an increase in water flow over the inflow.

Desertification indicators

Degree of soil salinity assessed by analysis of aqueous extracts (1:5) or electrical conductivity. According to the degree of salinity, soils are divided into 5 categories: non-saline, slightly saline, moderately saline, highly saline and very highly saline.

Conditions for salt accumulation in soils

Formation of salts in the soil

Changes in tree density or tree species. Here it is necessary to consider plant formations, which consist of various groups of green plants.

Combating desertification and drought

V.R. Williams identifies the following types of plant formations.

Woody vegetation of coniferous and deciduous forests
Meadow herbaceous vegetation.
Steppe herbaceous vegetation (feather grass, fescue, wheatgrass, yellow alfalfa, astragalus, ephemeral plants - tulips, bulbous bluegrass, goose onion).
Desert vegetation is characterized by exceptional poverty (saxauls, pistachios, etc., ephemeral).

In forestry practice, forest phytocenoses are usually called plantations. The main distinctive features of a phytocenosis include species or floristic composition, layering, abundance of species, quantitative and qualitative ratio of species, occurrence, productivity, seasonal and annual rhythm of development, etc. Changes in the density of trees and the phytocenosis in general are studied by their species composition.

Soil grading- a comparative assessment of the quality of soils (farmland) as a means of production in agriculture and forestry, expressed in quantitative indicators. The estimated properties are the thickness of the humus horizon, the content of basic nutrients in the soil, the exchange capacity of the absorbed complex, the reaction of the environment (pH), mechanical composition, salinity, etc. Quantitative assessment of soils based on their properties is carried out on a 100-point scale.

Drainage area (bottom)- the area of the bare bottom of the sea or reservoir as a result of the retreat of the coastline and a decrease in the water level in the reservoir (sea). The criterion for a dried bottom is the area of the bare bottom (m2, km2 or% relative to the area of the water area).

Monitoring methods

…soil salinity and salinity levels

Ground surveys - includes ground sampling of soils from various horizons of the soil profile for further analysis of water extract in laboratory conditions in order to determine water-soluble substances (dense residue) and various ions. Sommers can also be used for ground-based monitoring of soil salinity. Ground monitoring of soil salinity is carried out twice a year - in spring and autumn.

Remote monitoring of soil salinity - photographing a terrain (a given contour) from the air using an airplane or some other aircraft. In recent years, satellite imagery has also been used to assess salinity (especially the patchiness of land according to the degree of salinity). The resulting surveys are interpreted using ground surveys and used to compile cartographic materials for specific objects.

... deforestation

Ground monitoring is a ground-based study of plant composition - a set of plants growing together on a homogeneous territory, the nature of their composition, structure, species, species vitality, age, saturation (in a certain area), etc. They can be used for geobotanical mapping.

Taxation is the identification of taxonomic categories of plants. It includes: associations, group of associations, formations, group of formations, class of formations, type of vegetation, types, subtypes, species, etc.

Remote monitoring is the use of aerial photographs and satellite materials to study vegetation cover and their subsequent geobotanical mapping.

The frequency of monitoring is once every 3-5 years by forestry authorities (Goskompriroda), land supervision and the Ministry of Agriculture and Water Resources.

... degradation processes

Ground-based monitoring is carried out on the basis of field work (soil sections, half-sections, digging) and laboratory analyzes of soils, highlighting genetic divisions (types, subtypes), degree of moisture, degree of erosion, nutrients for compiling cartographic materials.

Mapping is one of the ways to study soil cover, which reflects the spatial distribution of soils; their properties are set out in the legend that accompanies the map materials. Agronomists, land managers, land reclamation workers, meadow farmers and other specialists base their work on these materials to select the best technical and economic solutions in accordance with natural conditions. In terms of the detail of display and the allocation of territory, soil maps are different: Overview (scale smaller than 1:1,000,000) - schematized; small-scale (from 1:1,000,000 to 1:300,000); medium-scale (from 1:300,000 to 1:100,000); large-scale (from 1:100,000 to 1:10,000).

The frequency of ground monitoring - once every 5 years - is carried out by the land supervision authorities and the Ministry of Agriculture and Water Resources.

Remote monitoring - the use of aerial photographs and satellite materials for soil mapping. The essence of remote sensing of soils (and vegetation) is the decoding (recognition) of photographs using photogrammetry and the visual method. The theoretical basis of remote sensing methods is the law of correlation between the properties of soils, the plant communities covering them and environmental conditions. The soil surface is almost always covered to some extent by vegetation. Therefore, the composition and condition of vegetation primarily influence the nature of the photographic image.

...drained bottom

Monitoring of the dried bottom - systematic observation and control of changes in the area of the dried bottom (and processes) using remote and ground-based (calculation) methods.

Remote sensing method is the use of aerial and space photography materials to draw up a plan (map) of the drained bottom and measure the area of the water body of a reservoir (sea).

Ground method - carrying out work to measure water depths using a bathometer and drawing up a plan of the bottom relief (bathymetric map).

The frequency of monitoring is annually by the Hydrometeorological Service and Land Supervision.

One of the global manifestations of soil degradation, and indeed the entire natural environment in general, is desertification. According to B. G. Rozanov (1984), desertification is a process of irreversible changes in soil and vegetation and a decrease in biological productivity, which in extreme cases can lead to the complete destruction of the biosphere potential and the transformation of the territory into a desert.

In total, more than 1 billion hectares are subject to desertification in the world on almost all continents (Fig. 15.3). The causes and main factors of desertification are different (Fig. 15.4). As a rule, desertification is caused by a combination of several factors, the combined action of which sharply worsens the environmental situation.

Rice. 15.3. Deserts and areas subject to desertification
(UN Conference on Desertification, 1977):

desertification degree: 1¾ very high; 2¾ high;
3 ¾ moderate; 4¾ hyperarid deserts

Rice. 15.4. Main factors and reasons for the development of desertification

In areas prone to desertification, the physical properties of soils deteriorate, vegetation dies, groundwater becomes saline, biological productivity drops sharply, and, consequently, the ability of ecosystems to recover is undermined. “And if erosion can be called a landscape ailment, then desertification is its death” (UN FAO Report). This process has become so widespread that it has become the subject of the international Desertification program. The UNEP (UN Environment Organization) report emphasizes that desertification is the result of a long historical process, during which adverse natural phenomena and human activities, reinforcing each other, lead to changes in the characteristics of the natural environment.

Desertification is both a socio-economic and natural process and threatens approximately 3.2 billion hectares of land, where more than 700 million people live.

Desertification problem

A particularly dangerous situation has developed in Africa in the Sahel zone (Senegal, Nigeria, Burkina Faso, Mali, etc.), a transitional bioclimatic zone (up to 400 km wide) between the Sahara Desert in the north and the savanna in the south.

The cause of the catastrophic situation in the Sahel is due to a combination of two factors: 1) increased human impact on natural ecosystems in order to provide food for a rapidly growing population and 2) changed meteorological conditions (prolonged droughts). Intensive grazing leads to excessive pressure on pastures and the destruction of already sparse vegetation with low natural productivity. Desertification is also facilitated by massive burning of last year's dry grass, especially after a period of rain, intensive plowing, lowering the groundwater level, etc. Knocked-out vegetation and highly loosened soils create conditions for intensive deflation of the surface layer of the earth. Changes in natural complexes and their degradation are especially noticeable during droughts. Many ecologists believe that in the list of atrocities against the environment, desertification can be placed second after the destruction of forests.

In the CIS, the Aral Sea region, the Balkhash region, the Black Lands in Kalmykia and the Astrakhan region and some other areas are susceptible to desertification. All of them belong to environmental disaster zones and their condition continues to deteriorate.

As a result of ill-conceived economic activities in these territories, deep irreversible degradation changes have occurred in the natural environment and, first of all, in its edaphic part. This resulted in a sharp decrease in the biodiversity of phyto- and zoocenoses and the destruction of natural ecosystems. Experts note that where, due to the conditions of the relief, soil quality, and the thickness of the first stand, only one sheep could be grazed, tens of times more were grazed. As a result, grassy pastures turned into eroded land. Over the past five years alone, the area of shifting sands in Kalmykia has increased by 50 thousand hectares.

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Consequences of soil degradation

1) Decrease in soil fertility

2) Deterioration of human health and increased morbidity in animals.

Desertification

A living organism reacts sensitively to changes in the chemical composition of the soil. An excess or deficiency of one or another element in the soil leads to negative consequences for the body.

Nitrates and nitrites, entering the human body, interact with hemoglobin in the blood. Hemoglobin contains 2-valent iron, and nitrates convert it into 3-valent iron, as a result of which red blood cells lose their ability to carry oxygen. When 20% of hemoglobin is blocked, oxygen deficiency (anomia) occurs. If 80% of hemoglobin is blocked - death.

3) Weakening the self-cleaning ability of the soil. Soil microorganisms break down pollutants into less toxic compounds.

4) Soil salinization. Occurs with poor drainage and improper watering. This leads to a rise in groundwater levels and the accumulation of easily soluble sodium chloride and sulfate, potassium and sodium carbonate in the soil. Even mild salinity reduces yield by 2 times.

5) Soil acidification. Soil acidity can be natural or secondary. Optimal soil pH: 5.5-8.0. If the pH drops to 3.6-4.0, virtually nothing will grow in that soil.

Combating land degradation

1) Rational use of soils. Elimination of environmentally unsound decisions.

2) Application of appropriate agricultural practices - no-moldboard farming, the use of crop rotation and the rejection of heavy equipment.

3) Reducing soil salinity (increasing water fees)

4) Application of hydraulic measures (strengthening slopes, retention of runoff)

5) Forest reclamation work (agroforestry - planting protective forest strips, land reclamation - drainage of waterlogged lands and swamps).

6) Chemical reclamation. It is divided into liming (soil acidity decreases, heavy metals are converted into insoluble compounds), gypsuming (leads to a decrease in soil salinity) and the use of mineral and organic fertilizers.

7) Land reclamation - a set of works to restore the productivity and economic value of disturbed lands. It takes place in 2 stages:

· Technical reclamation (delivery of land, planning...)

· Biological reclamation (restoration of the biological properties of the earth).

This is achieved by adding fertilizers, liming, and planting shrubs and trees.

Types of impacts on the lithosphere.

Lithosphere is the hard shell of the Earth.

Soil is a complex, multifunctional and multicomponent open multiphase structural system with fertility. Soil is a product of the joint activity of 5 components

Priming
Animals and plant organisms
Climate
Terrain
Age of the territory.

Arable land is 10% of the Earth's land area, pastures and hayfields are 20%, the remaining 70% are cold climate zones and areas unsuitable for agriculture.

The soil participates in the formation of river flow, and also, due to the entry of soil compounds into water bodies, is a factor in their bioproductivity.

Earth is the only planet in the solar system.

Every year, 7 million hectares of arable land are lost due to poor land management practices.

Mariinskaya Trench ©

Earthen bark©

The soil, or rather the Earth, is the only system that has soil©.

Violations of the natural environment are accompanied by the extraction and processing of minerals, this is expressed in the following:

The creation of large-sized quarries and embankments, which leads to the formation of a technogenic landscape, a reduction in land resources, and the depletion and destruction of soils.
Drainage of deposits, water intake for the technical needs of mining enterprises, discharge of mine and waste water depletes groundwater and surface water reserves and deteriorates their quality.
Drilling, blasting, and loading of rock mass causes deterioration in the quality of atmospheric air.
The processes mentioned above, as well as industrial noise, contribute to the deterioration of living conditions and habitats, a reduction in the number of plants and animals, and a decrease in agricultural yields.
Mining, extraction of minerals, burial of solid and liquid waste lead to changes in rock masses, flooding of deposits, and contamination of the subsoil.

Natural deposits are transported©

The main reasons for the decrease in areas suitable for agriculture:

Erosion (natural and artificial)
Pollution (industrial, agricultural, transport, household)
Construction allotment
Negative economic activities (destruction of forests, burning of vegetation, changes in the water regime of territories).
Development of land for mining.

Erosion is the destruction of soil under the influence of water, wind and mechanical means. Accelerated erosion is caused by human activities.

Based on the nature of the removal of soil particles, water and wind erosion are distinguished. Water erosion involves the transfer of soil particles into streams, rivers, and seas, as a result of which the entire cultural layer is washed away. Water erosion also includes coastal erosion. Wind erosion is the movement of dry soil particles.

Soil pollution is achieved by industrial enterprises (mining, thermal power plants using solid fuel). In Russia, about 7,000 hectares of land are occupied by solid waste landfills.

Testing of underground nuclear weapons for peaceful purposes ©.

St. Petersburg ©.

Soil classification:

Tundra gley
Peat bogs
Podzolic
Sod-podzolic
Swamp-podzolic
Forest gray
Meadow-chernozem
Chernozems
Serozems
Brown desert-steppe
Solontsy

Man is nature's friend:

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Land degradation (from the Latin degradatio - lit. decline) of land is a steady deterioration in the properties of the soil as an element of the ecological system, as well as a decrease in its fertility and economic value as a result of the influence of natural or anthropogenic factors.

Soil degradation is a common phenomenon around the world. Although soil quality can be improved through reclamation, most anthropogenic impacts reduce soil quality by directly or indirectly causing soil degradation.

The idea of the causes of soil degradation and soil cover is not fully established. As a rule, degradation phenomena associated with human activity are most actively studied. The changes that occur in this case are mainly local in nature, territorially limited to one or another type of economic activity.

Some of the reasons for soil degradation of natural and anthropogenic nature:

- slow tectonic subsidence or uplift of the territory;
- earthquakes;
- volcanic eruptions (including mud ones), geysers, thermal springs;
- weathering of rocks;
- flooding of lands during the passage of typhoons, tsunamis and tides;
- waterlogging due to changes in thermal conditions;
- improper use of fertilizers and pesticides. The application of high doses of nitrogen fertilizers sometimes negatively affects the soil structure and reduces the erosion resistance of soils. The use of increased doses of pesticides containing salts of heavy metals can also reduce soil fertility, since when processed, beneficial microorganisms and worms are destroyed, and the acidity also changes;
- reclamation works. If the technology of such work is incorrect, the humus layer of the soil is reduced, the fertile layer of soil is covered with soil-forming rock;
- logging. The undergrowth, grass cover, litter and top humus layer of soil are damaged and destroyed. Tractor drags and transportation of timber along temporary roads cause especially great damage to the soil;
- uprooting of forests. Together with the roots of trees, a large amount of humus is carried out of the soil;
- Forest fires. Along with the forest, forest litter and grass are destroyed. The effect of fire spreads to the humus layer of the soil, degradation of forest soils, and fires on drained peat soils occur. On pastures and arable lands, the completely organic layer of soil burns out;
- lack of rational relationships between agriculture and livestock raising;
- destruction of vegetation during fuel procurement;
- destruction of vegetation and soil cover during road and industrial construction, geological exploration, mining, etc.;
- secondary salinization, alkalization and flooding of irrigated lands and soil salinization not associated with irrigation.
- one of the reasons for the reduction in the area of cultivated land is intense water and wind erosion, caused by the growing scale of influence of the anthropogenic factor on soils. Soil erosion has become a scourge of agriculture, despite measures to limit it. In Western European countries, erosion covers 50-60% of the territory, in the USA up to 75% of all lands. Soil destruction manifests itself in its washouts and erosion, in the formation of streams, ravines, dust storms and other negative phenomena. 31% of land is subject to water erosion, and 34% to wind erosion. The annual loss of soil from the Earth's surface reaches 134 t/km2, and up to 60 billion tons of soil cover is washed into the World Ocean.

Desertification. There is a misconception that desertification is the encroachment of deserts into more productive areas. Desertification actually refers to the degradation of land in dry areas that occurs due to various factors, including climate fluctuations and human activities. The soils of desertification areas are characterized by low fertility, which, in combination with low and variable precipitation, leads to the fact that biological productivity in areas of significant desertification does not exceed 400 kg/ha per year of dry matter.

In accordance with climatic conditions, deserts should occupy an area of about 48 million km 2 in the world (including ice sheets, i.e. ice deserts). In fact, according to soil-botanical data, their area reaches 57 million km 2. The difference between these two figures, equal to 9 million km 2, represents anthropogenic deserts. Desertification of varying degrees is developing on another 25 million km 2. One sixth of the world's population lives in areas threatened by desertification. World economic losses from desertification, as of 1990, were estimated at 42 billion dollars annually.

Signs of desertification are: a decrease in the degree of soil cover with vegetation, an increase in the reflectivity (albedo) of the soil surface, a significant loss of perennial plants, especially trees and shrubs, soil degradation and erosion, the encroachment of sand and soil salinization. All these natural processes are typical for arid landscapes, and they are regulated naturally. But when they are interconnected with human actions, many changes become irreversible.

The largest number of drylands is found in Asia and Africa, which account for almost 2/3 of the total area of such lands. This is followed by North America, Australia, South America and Europe. The analysis shows that in all major regions of the world, pastoral lands are most susceptible to desertification. In Africa, Asia, North and South America, Australia and Europe, desertification has already affected 70-80% of all pastures located in dry areas. In second place are rich arable lands (especially in Asia, Africa and Europe), in third place are irrigated lands (especially in Asia).

In Russia, the total area of dry and arid lands is over 610 thousand square meters. km. According to various estimates, about 100 million hectares of land in 35 constituent entities of the Russian Federation are susceptible to desertification or are potentially dangerous in this regard. Desertification processes are most developed in the south of Russia: in the Caspian region, including the Astrakhan region, the Republic of Kalmykia, lowland Dagestan, the south of the Volgograd region, the areas bordering Kalmykia in the Rostov region and the Stavropol Territory.

The most likely causes of desertification are considered to be unfavorable weather conditions, destruction of vegetation, irrational environmental management, mechanization of agriculture, and transport without compensation for damage caused to nature.

Over the past 50 years, an area of just under half of South America has been turned into barren desert. This occurred as a result of excessive overgrazing of pastures, predatory deforestation, unsystematic farming, construction of roads and other engineering structures, rapid growth of population and technical means.

Among the factors leading to desertification in arid regions of the globe, there are common ones that play a special role in intensifying desertification processes. These include:

· destruction of vegetation cover and destruction of soil cover during industrial and irrigation construction;
· degradation of vegetation cover due to overgrazing; destruction of trees and shrubs as a result of fuel procurement;
· deflation and soil erosion during intensive rainfed farming;
· secondary salinization and waterlogging of soils under irrigated farming conditions;
· destruction of the landscape in mining areas due to industrial waste, discharge of waste and drainage waters.

Among the natural processes leading to desertification, the most dangerous are:

1) climatic - an increase in aridity, a decrease in moisture reserves caused by changes in macro- and microclimate;
2) hydrogeological - precipitation becomes irregular, groundwater supply becomes episodic;
3) morphodynamic - geomorphological processes become more active (erosion, deflation, etc.);
4) soil - drying out of soils and their salinization;
5) phytogenic - degradation of soil cover;
6) zoogenic - reduction in the population and number of animals. Land degradation in Russia is caused by a complex of reasons. The most important of them is unsustainable agricultural land use, which poses a real threat to the country's food security. Land degradation is particularly dangerous in the arid (suitable for agriculture) zone of Russia, where these processes are aggravated by drought.

Changes in natural complexes and their degradation are especially noticeable during droughts. In the CIS, the Aral Sea region, the Balkhash region, the Black Lands in Kalmykia and the Astrakhan region and some other areas are susceptible to desertification. All of them belong to environmental disaster zones and their condition continues to deteriorate. As a result of the closure of the Adjidarya Strait in 1980 between the Caspian Sea and the Karobogaz Gulf, serious anthropogenic changes in the ecological balance are occurring. In just 5 years, the bay completely dried out, and a typical salt desert formed over a vast area of 10 thousand km. The vast region of the Aral Sea is an area of catastrophic environmental disturbances. As a result of the regulation of the Amudarya and Syr Darya rivers feeding the sea and the intensive use of their waters for irrigation, the level of the Aral Sea has dropped sharply and the seabed has been exposed over large areas, where desertification processes are now rampant. As a result of ill-conceived economic activities, deep irreversible degradation changes in the natural environment occurred in these territories. This resulted in a sharp decrease in the biodiversity of phyto- and zoocenoses and the destruction of natural ecosystems.

Experts note that where, due to the conditions of the relief, soil quality, and the thickness of the first stand, only one sheep could be grazed, tens of times more were grazed. As a result, grassy pastures turned into eroded land. For example, in the last five years alone, the area of shifting sands in Kalmykia has increased by more than 50 thousand hectares. The natural process of destruction by water and wind of the top layer of soil, washing away and dispersing its particles is greatly enhanced and accelerated when people plow up too much land and do not allow the soil to “rest.” According to geologists, before people began to engage in agricultural activities, graze livestock and plow land, rivers annually carried about 9 billion tons of soil into the World Ocean. Nowadays this amount is estimated at approximately 25 billion tons.

Soil erosion not only reduces fertility and reduces crop yields. As a result of soil erosion, artificially constructed water reservoirs become silted much faster than is usually envisaged in projects, and the possibility of irrigation and obtaining electricity from hydroelectric power plants is reduced. In Russia, soil erosion removes about 50 thousand hectares of land from agricultural use every year. In arid zones, pastures are gradually disappearing. Only stagnation in agriculture so far saves many of them from complete degradation. The economic damage from these unfavorable processes is enormous.

According to expert forecasts, in the near future the area of drought-prone steppe or forest-steppe zones in Russia may almost double; Moreover, this zone will extend to the north up to the southern borders of the Moscow, Vladimir and Nizhny Novgorod regions. The dry steppes of the Volga region and the North Caucasus may give way to real desert. A particularly difficult situation arises when not only the soil layer is demolished, but also the parent rock on which it develops. Then the threshold of irreversible destruction comes, and an anthropogenic desert arises.

5.Biogeochemical cycles, their types and ecological role.

6. Anthropogenic influence on the cycles of basic nutrients in the biosphere.

7. The main stages of change in the relationship between man and nature in the course of its historical development.

8. The problem of global climate change on the planet: possible causes, consequences, solutions.

9. Desertification as a global environmental problem.

10.The problem of providing fresh water as a global environmental problem.

11.The problem of soil degradation: causes and consequences on a global scale.

12.Environmental assessment of the global demographic situation.

13.Global environmental problem of pollution of the World Ocean. What are the reasons and environmental dangers of this process?

14.The problem of reducing biological diversity: causes, environmental consequences, possible solutions to the problem.

15.Environmental factors: concept and classification. Basic mechanisms of action of environmental factors on living organisms.

16.Adaptation: the concept of adaptation, its ecological role.

17. Basic patterns of the action of environmental factors on living organisms.

18.Types of biotic relationships in nature, their ecological role.

19. Concepts – stenobiontity and eurybiontity.

20. The concept of population, its biological and ecological meaning.

21.Number, density, population growth. Regulation of numbers.

22. Fertility and mortality in a population: theoretical and ecological. Their determining factors.

23. Sex structure of the population and its determining factors.

24. Age structure of the population, main types of populations depending on the age ratio.

25.Spatial structure of the population and its determining factors.

26. Ethological (behavioral) structure of the population and its determining factors.

27.Ecological strategies of populations (r- and k-life strategies). Their ecological meaning.

28. Survival and survival curves of organisms in a population, the ecological meaning of survival curves.

29. Population growth curves, ecological significance of each stage of growth.

30. The concept of an ecosystem, its main components, types of ecosystems.

31. Pyramids of numbers, biomass, energy in ecosystems, their ecological meaning.

32.Energy flow in the ecosystem. 10% energy rule.

33.Flow of matter in an ecosystem. The fundamental difference between the flow of matter and energy.

34.Food chains. The effect of toxicant accumulation in food chains.

35. Productivity of ecological systems. The most productive ecosystems of the globe, their environmental problems.

36.Ecological succession, types of succession.

37.Producers, consumers and decomposers, their place in the food chain and ecological role in ecosystems.

38. The place and role of man in the ecological system.

39. Natural and artificial ecosystems, their environmental sustainability.

40. The concept of environmental pollution, natural and anthropogenic pollution.

41. The main types of anthropogenic impact on the environment: chemical, energy, biological pollution of the environment.

42. Ecological situation and human health. Human adaptation to extreme environmental factors.

43. Standardization of environmental quality: goals of regulation, types of standards.

44. The principles underlying the development of maximum permissible concentrations.

45.Habitat monitoring: concept, goals and types of monitoring.

46. Environmental problems of the Far East.

9. Desertification as a global environmental problem.

Desertification or desertification is the degradation of land in arid, semi-arid (semiarid) and arid (subhumid) regions of the globe, caused by both human activity (anthropogenic causes) and natural factors and processes.

Land degradation is the reduction or loss of biological and economic productivity of arable land or pastures as a result of land use. It is characterized by drying out of the land, withering of vegetation, and a decrease in soil cohesion, as a result of which rapid wind erosion and the formation of dust storms become possible.

Information about the dry regions of the world

Dry regions occupy 41 percent of the earth's landmass. More than 2 billion people live in this territory (information from 2000). 90 percent of the population are from developing countries with low development indicators.

Environmental consequences

The consequences of desertification in environmental and economic terms are very significant and almost always negative. Agricultural productivity decreases, the diversity of species and the number of animals decreases, which, especially in poor countries, leads to even greater dependence on natural resources. Desertification limits the availability of basic ecosystem services and threatens human safety. It is an important obstacle to development, which is why the United Nations established the World Day to Combat Desertification and Drought in 1995, then declared 2006 the International Year of Deserts and Desertification, and subsequently designated the period from January 2010 to December 2020 as the UN Decade , dedicated to deserts and the fight against desertification.

10.The problem of providing fresh water as a global environmental problem.

Between 1900 and 1995, global freshwater consumption increased 6-fold, more than double the rate of population growth. Currently, almost 30% of the world's population lacks clean water. If current trends in freshwater consumption continue, by 2025 every two out of three inhabitants of the Earth will live in conditions of water scarcity.

Groundwater supplies the needs of 30% of the world's population. Of particular concern to humanity is their irrational use and methods of exploitation. Groundwater extraction in many regions of the globe is carried out in volumes that significantly exceed nature’s ability to renew it.

Protecting the quality of water resources poses a challenge. The use of water for economic purposes is one of the links in the water cycle. But the anthropogenic link of the cycle differs significantly from the natural one in that only part of the water used by humans returns to the atmosphere through the process of evaporation. Another part of it, especially when supplying water to cities and industrial enterprises, is discharged back into rivers and reservoirs in the form of wastewater contaminated with industrial waste. This process continues for thousands of years. With the growth of the urban population, the development of industry, and the use of mineral fertilizers and harmful chemicals in agriculture, the pollution of surface fresh waters began to acquire a global scale.

The World Ocean is the largest ecological system of planet Earth and consists of the waters of four oceans (Atlantic, Indian, Pacific and Arctic) with all interconnected adjacent seas. Sea water makes up 95% of the volume of the entire hydrosphere. Being an important link in the water cycle, it provides nutrition to glaciers, rivers and lakes, and thereby the life of plants and animals. The sea ocean plays a huge role in creating the necessary conditions for life on the planet; its phytoplankton provides 50-70% of the total volume of oxygen consumed by living beings.

The scientific and technological revolution brought radical changes in the use of the resources of the World Ocean. At the same time, many negative processes are associated with scientific and technological revolution, and among them is the pollution of the waters of the World Ocean. Ocean pollution with oil, chemicals, organic residues, burial sites of radioactive production, etc. is catastrophically increasing. According to estimates, the World Ocean absorbs the main part of pollutants. The international community is actively searching for ways to effectively protect the marine environment. Currently, there are more than 100 conventions, agreements, treaties and other legal acts. International agreements regulate various aspects that determine the prevention of pollution of the World Ocean, including:

prohibition or limitation under certain conditions of discharges of pollutants generated during normal operation (1954);

prevention of intentional pollution of the marine environment with operational waste from ships, as well as partly from fixed and floating platforms (1973);

prohibition or restriction of dumping of wastes and other materials (1972);

preventing pollution or reducing its consequences as a result of accidents and disasters (1969, 1978).

In the formation of a new international legal regime for the World Ocean, the leading place is occupied by the UN Convention on the Law of the Sea (1982), which includes a set of problems of the protection and use of the World Ocean in modern conditions of the scientific and technological revolution. The Convention declared the international seabed area and its resources to be the common heritage of mankind.

Desertification is currently one of the most significant global problems of humanity. During the plowing of fields, myriads of particles of fertile soil cover rise into the air, disperse, are carried away from the fields by streams of water, are deposited in new places, and are irretrievably carried away in huge quantities into the World Ocean. The natural process of destruction by water and wind of the top layer of soil, washing away and scattering of its particles is greatly enhanced and accelerated when a person plows too much land and does not allow the soil to “rest.”

Under the influence of living organisms, water and air, the most important ecosystem, thin and fragile, soil, which is called the “skin of the Earth,” is gradually formed on the surface layers of the lithosphere. This is the guardian of fertility and life. A handful of good soil contains millions of microorganisms that maintain fertility. It takes a century for a layer of soil 1 cm thick to form. It can be lost forever in one field season. According to geologists, before people began to engage in agricultural activities, graze livestock and plow land, rivers annually carried about 9 billion tons of soil into the World Ocean. Nowadays this amount is estimated at approximately 25 billion tons.

A particularly difficult situation arises when not only the soil layer is demolished, but also the parent rock on which it develops. Then the threshold of irreversible destruction comes, and an anthropogenic desert arises. The Shillong plateau in the Cherrapunji region, located in northeast India, presents a striking picture. This is the wettest place in the world, where on average more than 12 m of precipitation falls per year. But during the dry season, when the monsoon rains stop (October - May), the Cherrapunji region resembles a semi-desert. The soils on the slopes of the plateau have been practically washed away, exposing barren sandstones.

As a result of human activity, by the last quarter of the 20th century. More than 9 million km2 of deserts appeared, and they already covered 43% of the total land area.

Desertification and devastation can occur in any climate as a result of the destruction of the natural system. But in arid regions, drought also becomes the “engine” of desertification. Desertification, developing as a result of inept and immoderate economic activity, has more than once destroyed entire civilizations. In schools all over the world, children are taught in history lessons that people need to know history in order to learn lessons for the future. Has humanity learned lessons from the history of the collapse of past civilizations buried under sand? The main difference between the experience of history and today is the pace and scale. Excessively active economic activity, the pressure of which had accumulated over centuries and even millennia, has now been compressed into decades. If earlier individual civilizations perished, buried by sands, now the process of desertification, originating in different places and having different regional manifestations, has assumed a global scale. The accumulation of carbon dioxide in the atmosphere, increased dust and smoke levels in the atmosphere accelerate the aridization of land. This process covers not only arid regions.

The expanding area of deserts contributes to the development of dry climatic conditions, which are likely to have a large influence on the frequency of multi-year droughts. The vicious circle closes.

The fate of forests and the history of humanity on all continents were closely interconnected. Forests served as the main source of food for primitive communities that lived by hunting and gathering. They were a source of fuel and building materials for the construction of dwellings. Forests served as a refuge for people and, to a large extent, as the basis for their economic activity. The life of forests and the life of people, the connections between them are reflected in the culture, mythology, and religion of most peoples of the world. About 10 thousand years ago, before the advent of agricultural activity, dense forests and other forested areas occupied more than 6 billion hectares of land surface. By the end of the 20th century, their area decreased by almost 1/3 and now they occupy only a little more than 4 billion hectares. In France, for example, where forests initially covered about 80% of the territory, by the end of the 20th century. their area decreased to 14%; in the USA, where forests at the beginning of the 17th century. Almost 400 million hectares were covered; by 1920, 2/3 of this forest cover was destroyed.

Dedicated to solving this problem Convention to Combat Desertification in Those Countries Experiencing Serious Drought and/or Desertification, Particularly in Africa(1994). Its main focus is on improving soil fertility and restoration, as well as protecting and rationally using land and water resources. It emphasizes the importance of creating a healthy environment for local people to help them combat soil depletion. It also contains criteria for the development of national action programs by affected countries and gives an unprecedented role to NGOs in the development and implementation of action programs. The treaty, which was signed by 192 countries, came into force in 1996.

Various UN agencies provide assistance in the fight against desertification. UNDP funds efforts to combat desertification through the Center for Dryland Development in Nairobi. IFAD has contributed US$3.5 billion to dryland development projects over more than 27 years. The World Bank organizes and finances programs aimed at protecting fragile drylands and increasing their agricultural productivity. FAO promotes sustainable agricultural development by providing broad, practical assistance to governments. UNEP supports regional programs of action, data assessment, capacity building and public awareness of the issue.

To further raise public awareness of this issue, the UN General Assembly declared 2006 the International Year of Deserts and Desertification, inviting active participation by individual countries, international organizations and civil society.