Природные ресурсы мира = World Natural Resource. Учебно-методическое пособие

- Low-yield/poorly productive and unproductive lands (ice covers, cold and hot/arid deserts, coastal sands, rocks, lakes, rivers and reservoirs, anthropogenic badlands). [18]

The distribution of land resources by regions and countries depends on many factors, like physical-geographical features - relief and climate, the level of demographic pressure and historical features of the territory. Thus, most of the cultivated land is located in Africa and South America. For example, in Southeast Asia, 92% of land area is under agricultural use. Around 40% of the world's arable land accrues to the United States, India, and Russia.

By share of arable land, the leaders are Ukraine, India, Bangladesh, and Denmark (the ratio of the arable area to total area of the country reaches 56-57%).

A high share of arable lands is an indicator of a high natural agrarian potential.

The following countries are the leaders in pasture area:

•Australia

•China

•USA

•Kazakhstan

•Brazil

•Argentina

In the land fund pasture lands prevail in the countries: Mongolia - 75%

Kazakhstan - 70%

Australia and Argentina - 50-55%

Russia is ranked first in the reserves of other lands: 700 million hectares, which occupies much larger area than productive lands. Second place belongs to Canada (355 million hectares), China (307 million hectares), Algeria (195 million hectares), the United States (193 million hectares) and Libya (159 million hectares).

The availability of land resources

The availability of land resources is the relationship between the total land area (of a certain type) to the total amount population (ha/person). According to this indicator, the leaders are Australia (40.4 ha/person) and Canada - (32.4 ha/person), Russia (12.07 ha/person).

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Land Degradation

Arable and pasture lands are under threat due to growing utilization. Every year, between 5 to 7 million hectares of land worldwide is added to the existing degraded farmland. Intensive and irrational farming results in rapid soil erosion, salinization (when evaporation of water brings to the accumulation of salts in the uppermost soil layer on which crops cannot grow). Overirrigation also creates water logging of the topsoil and crop roots are affected, and the crops deteriorate.

Soil

Soil is extremely important for arable cropping. It regulates: soil aeration and gaseous exchange rates; soil temperature; soil infiltration and erosion; the movement and storage of water; nutrient supply; root penetration and development; soil workability; soil trafficability; the resistance of soils to structural degradation.

Soil structure is ranked on the size, shape, firmness, porosity and relative abundance of soil aggregates and clods. Soils with good structure have friable, fine, porous, subangular and subrounded (nutty) aggregates. Those with poor structure have large, dense, very firm, angular or subangular blocky clods that fit and pack closely together and have a high tensile strength.

The loss and degradation of good land are caused by various factors, most of them are related to human development. The primary causes are:

•Deforestation

•Overgrazing

•Agricultural activities

•Increased flooding

•Industrialization

•Overexploitation for fuelwood

The use of chemical fertilizers poisons the soil, and the land becomes unproductive. The expansion of urban and industrial centers results in shrinkage of agricultural land and forests. Soils of various types support a wide variety of crops. Irrational use of our ecosystems leads to loss of valuable soil. Deforestation leads to rapid soil erosion. The soil is washed into streams and is transported into rivers and finally lost to the

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sea. The process is evident in areas of deforestation, which has led to erosion on steep hill slopes, e.g., in the Himalayas and the Western Ghats. Such areas are called ‘ecologically sensitive areas’ or ESAs.

Fig 2. Causes of soil degradation in the world. [11]

Soil conservation practices can reduce soil erosion caused by flooding, wind and other agents.

1)Afforestation

2)Checking Overgrazing 3)Constructing Dams

4)Changing Agricultural Practices:

- Contour plowing - Terracing - No till farming (no-tillage) - Cover Crop - Crop rotation.

Questions:

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CHAPTER IV

FOREST RESOURCES

Forest resources

Forest functions

Classification of forests

Deforestation

Forest resources

Forests represent a complex ecosystem. Forests serve as houses for a large variety of life forms such as plants, mammals, birds, microorganisms, and fungi, which plays a fundamental role in the process of decomposition of dead organic matter and soil enrichment. According to FAO data, about 4 billion hectares of forests cover the earth’s surface. It is approximately 30 % of the Earth's total land area. The forest ecosystem consists of two components:

-the non-living (abiotic)

-and the living (biotic)

Climate, soil refer to the non-living components, and the living component includes plants (trees, shrubs, climbers, grasses and herbs) in the forest, animals, microorganisms, and other forms of life. Such factors, as physical, geographical, climatic and ecological, determine there availability of different types of forests like:

-Evergreen forest (species having leaves all throughout the year)

-Deciduous forest (species having leaf-fall during particular months of the year).

Forest resources can be divided into three categories:

Natural forests, semi-natural (disturbed or partly developed) forests, and plantation.

Forest resources include:

• Forest reserves

• Non-timber forest product ( animals, nuts, seeds, berries, mushrooms, oils, foliage, medicinal plants, peat, fish, spices, and forage).

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Quantitative assessment of forest resources:

•Forest area (the area of all lands belonging to the forest fund of a country),

•Forested area (the area covered by forests),

•Forest coverage in relation to land area

•Volume of wood

Forest Functions

1) Watershed protection

Reduction of surface water flow run-off Prevention against flash floods and soil erosion

Production of prolonged gradual run-off which prevents the droughts.

2) Atmospheric regulation.

Maintainance of carbon dioxide levels important for plant growth Maintainance of the local climatic conditions.

3) Protection against natural resources.

Physical obstacles or barriers that impede downslope mass movements such as rockfalls, landslides, debris flows, and avalanches. Holding soil (by preventing rain from directly washing soil away).

4) Local use (Consumptive use)

•Food - gathering plants, fishing, hunting from the forest

•Fodder

•Fuel wood

•Materials for construction purposes

•Timber – household articles and construction.

•Sericulture

•Apiculture

•Medicinal plants

Market use

5) Habitat for a vast array of plants and animals

About 90% of the total stock of organic matter is concentrated in forests.

In terms of productivity:

•Productive forests are forests, which have potential to reproduce commercial timber.

•Unproductive are forests that can produce only fuel wood.

In terms of accessibility (for economic profitability of development):

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•Accessible

•Inaccessible

Since 1946, FAO has been monitoring the world's forests at 5 to 10 year intervals.

Classification of forests

There are different types of forests, which are generally classified according to location and climate. 1. Tropical rainforests 2. Subtropical forests 3. Mediterranean forests 4. Temperate forests 5. Coniferous forests 6. Montane forests 7. Plantation forests.

Two forest belts are distinguished: northern and southern. The northern - 2 billion hectares.

Russia, Canada, and the USA have the largest timber reserves in the northern belt. Coniferous forests occupy 67%, deciduous forests - 33%. Species diversity is limited; the increment is low (coniferous forests in Russia - 1.3 m³ per 1 hectare, Finland - 2.3 m³, USA - 3.1 m³).

The southern belt occupies 2 billion hectares, 97% are broad-leaved forests. Half of the area is occupied by high forests, the rest are sparse forests, bushes and abandoned lands. The annual growth and total timber reserves are much higher. The leading countries are Brazil, the Democratic Republic of the Congo, and Papua New Guinea.

Deforestation

Up to the 7th-century forests covered up to 70% of the area in Europe. The industrial revolution of the 17th-19th centuries led to the deforestation of Europe, North America, and affected other regions. Forests of the USA (except for Alaska), occupied 384 million hectares in the period of settling by Europeans, and by the middle of the 20th century, the area had reduced by 262 million hectares. In the period 1850-1980 the forested area of the Earth's forests decreased by 15%.

At present 30% of the earth’s land area (> 3,5 billion hectares) is covered by forests, while the original forest cover was estimated to cover approximately six billion hectares [7]. Mostly deforestation has been observed in the temperate and sub-tropical areas. The FAO FRA

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2001 and 2010 reports indicate considerable deforestation in the world during 1990-2010.

In fact many temperate countries now are recording increases in forest area, and deforestation in the developed temperate countries is no longer significant [2]. Nowadays the tropical rainforests capture most attention, and 60 per cent of the deforestation occurred in tropical forests in the period from 1990 to2010 was in moist deciduous and dry forests. Annual change in forest area by region and subregion in the world, in the period from 1990 to 2010 is shown in table 5.

Rowe et al. [15] estimated that 15 % of the world’s forest was converted to other land uses between 1850 and 1980.

Deforestation was estimated to be at the rate of 9.2 million hectares per annum from 1980-1990, 16 million hectares per annum from 19902000. In the period 2000-2010 the rate decreased to 13 million hectares per annum.

Table 5 Annual change in forest area by region and subregion, 1990-2010 [2]

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Over use and irrational use, technological and industrial growth, population growth and increasing consumption levels are major factors causing depletion of forest resources. Some other factors are mining, submergence due to big dams, shifting cultivation, use of forestlands for rehabilitation, agriculture, transport, and tourism. All these activities are causing qualitative as well as quantitative depletion of forests.

Direct causes of deforestation:

•Expansion of farming land

•Logging and fuel wood

•Overgrazing

•Fires

•Mining Urbanization/industrialization and infra-structure

•Air pollution

•Wars and role of the military

•Tourism

Indirect causes of deforestation:

•Colonialism Exploitation by industrialized countries

•The debt burden Overpopulation and poverty

•Transmigration and colonisation schemes

•Land rights, land tenure and inequitable land distribution and resources Economic causes - development/land conversion value, fiscal policies,

•markets and consumerism

•Undervaluing the forest

•Corruption and political cause

Questions:

What are the general characteristics of forest resources? Characterize forests in terms of productivity and accessibility. Describe the roles of forests.

What are the principals of quantitative assessment of forest resources?

List the types of forests.

What was the main reason of deforestation in Europe?

Describe the annual change in forest area by region and subregion in the world.

Describe the causes of deforestation.

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CHAPTER V

WATER RESOURCES

Forest resources

Forest functions

Classification of forests

Deforestation

World water supply and distribution

Water is found everywhere on Earth, and is the only substance that can naturally occur as liquid, solid, or gas. The Earth contains around 1,4 billion km³ of water. Approximately 96 % is stored in the oceans, 1,7 % in glaciers, permanent snow, sea ice, and polar ice caps, while another 1,7 % exists as groundwater, in rivers, lake, wetlands, and the soil. The remaining 0,1 % is concentrated in the Earth’s atmosphere. Water is not evenly distributed over the continents and varies season to season, year to year. Approximately two-thirds of the population – around 4 billion people – lives in locations that receive only one-fourth of the world’s annual precipitation. For example, the Amazon River Basin of the Southern America has approximately 15 % of the world’s surface water runoff, but contains only 0,4 percent of the Earth’s population. Asia, on the other hand, has 69% of the world population, but only 36 % of the Earth’s surface water runoff [10]. Such disparities result in water shortages and need to:

Store water in reservoirs Use groundwater resources Manage water supply system

Water cycle

Mineralogical evidence suggests that water was present on the Earth’s surface by 4.4 billion years ago, soon after accretion, and we know from the existence of sedimentary rocks laid down in water that the

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