Key points to remember :

• Soil Erosion: The removal of the top soil by running water and wind.
• Rain Water Harvesting : It is the process of collecting rain water from roof top and directing it to an appropriate location and storing it for future use.
• Biomes: A region with naturally occurring flora and fauna that have adopted themselves to their environment.
• Mulching : The bare ground between plants is covered with a layer of organic matter like straw. It helps to retain soil moisture.
• Biosphere reserves: Series of protected areas linked through a global network, intended to demonstrate the relationship between conservation and development.
• Temperature and rainfall are two main climatic factors responsible for soil formation. Rainfall contributes in breaking the rocks by applying pressure. Temperature fluctuations between hot and cold also form cracks in the rocks.
• Reasons for land degradation are: Ever-growing demand of the growing population and Destruction of forest‘cover.
• Land is an important resource because it provides surface for agriculture, living, forestry, industries, construction, etc. Most activities take place on land.
• Steps taken by the government include establishment of natural parks and wildlife sanctuaries in different parts of India. Their purpose is conservation of vegetation and wildlife, respectively.
• Three ways to conserve water are as under:
  • Rainwater harvesting: It is a method of collecting water while it rains so that it may come of use in the future.
  • The canals used for irrigation should be properly built so that loss of water does not take place while the water is transported to the field.
  • In dry regions, drip or trickle irrigation is suggested.
• The reasons behind uneven population distribution are mainly the varied conditions of land and climate.
• Three common land use forms are: (i) As cropland, (ii) Pasture, (iii) Forests.
• Human factors affecting land use pattern are population and technology.
• The thin layer of grainy substance covering the surface of the earth is called soil.
• The right mix of minerals and organic matter is needed to make soil fertile.
• The rock from which soil is derived is called parent rock.
• Two factors that threaten soil as a resource are soil erosion and its depletion.
• Shelter belts are used to protect the soil in coastal and dry regions.
• The earth’s surface has about three- fourths water, so it is called “water planet”.
• Fresh water is found in the forms of groundwater, water in rivers and lakes, and water vapour.
• The process involved in the formation of rain is called “water cycle”.
• Africa, West Asia, South Asia, parts of western USA, northwest Mexico, parts of South America, and Australia face water scarcity.
• Water harvesting is a method to save surface run-off.
• A vulture feeds on dead livestock and so it cleanses the environment.
• Evergreen forests never shed their leaves whereas deciduous forests shed their leaves once a year.
• The social programme of planting trees, organized at the community level is called vanamahotsava.

Land

• Land covers about 30% of the total area of the earth’s surface.
• Due to variations in topography, all parts of the land may not be habitable.
• 90% of the world population lives only on 30% of the land area.
• The remaining 70% of the land is either sparsely populated or uninhabited.
• Plains and river valleys are densely populated because they are suitable for agriculture.
• On the other hand, steep slopes and water logged areas are sparsely populated.

Land Use

• Land is used for various purposes; like agriculture, forestry, mining, building houses, roads, industries, etc. Factors which affect the use of land are topography, soil, climate, minerals and availability of water. Human factors also determine the land use pattern. Ownership of land also determines the land use pattern.
• Increasing population means there is an ever growing demand for land. But the availability of land is limited. Land degradation, landslides, soil erosion, desertification are the major threats to the environment.
• Human encroachment has led to large scale destruction of forest cover and arable land. This is creating a danger for quality of land. Land degradation can be prevented by afforestation, land reclamation, regulated use of chemical pesticide and fertilizers, and by checking overgrazing.

Soil

• The topmost layer of land which is composed of grainy substance is called soil. Soil is made up of organic matter, minerals and weathered rocks. Soil formation takes place because of weathering of rocks. The soil becomes fertile because of the right combination of minerals and organic matter.
• Soil Profile : The arrangement of different layers of soil at a place is called soil profile. The typical soil profile is composed of following layers:
  1. Topsoil: Topsoil is composed of humus and fine particles of clay and sand.
  2. Subsoil: This is the second layer of soil. It is composed of sand, silt and clay.
  3. Weathered Rock Material: The third layer is composed of large pieces of rocks.
  4. Bedrock: The last layer of soil profile is composed of huge rocks.

Factors of Soil Formation:

Following are the factors of soil formation:

• Parent Rock: The parent rock determines the colour, texture, permeability, chemical property and mineral content of the soil.
• Climate: Temperature and rainfall influence the rate of weathering.
• Relief: Altitude and slope determine the accumulation of soil at a place.
• Flora, fauna and microorganism: These are the biotic factors which affect the rate of humus formation.
• Time: Time determines the thickness of soil profile.

Soil Erosion

Removal of topsoil is called soil erosion. Deforestation, overgrazing, overuse of chemical fertilisers or pesticides, rain-wash, landslides and floods are the factors which lead to soil erosion.

Methods of Soil Conservation:

• Mulching: In this method, the bare ground is covered with organic matter like straw. Covering the soil helps in retaining the moisture in soil.
• Contour Barriers: Contour barriers are made by placing stone, grass or soil along the contour. Trenches are made in front of the barriers to collect water. Contour barriers help in preventing soil degradation which may happen due to rainwash.
• Rock Dam: Rocks are piled up to make a dam. Such dams slow down the flow of water. Thus, it prevents gullies and soil loss.
• Terrace Farming: Terrace farming is done in hilly areas. Plots are made in the shape of terraces to ensure flat surface for growing the crops. It helps in reducing soil erosion which may happen because of run-off.
• Intercropping: In this method, different crops are grown in alternate rows. Crops are grown at different times. It helps in preventing soil erosion from rain wash.
• Contour Ploughing: In this method, ploughing is done parallel to the contours of the hill slope. This helps in forming a natural barrier and prevents water from flowing down the slope.
• Shelter Belt: This method is used in coastal areas and in dry regions. Rows of trees are planted along the boundary of the farmland. This helps in preventing soil erosion from wind.

Water

About three-fourths of the earth’s surface is covered with water. But most of the water on earth is in the oceans. Ocean water is saline and hence is not fit for human consumption. Just 2.7% of the total water on the earth is available as freshwater. But 70% of the total freshwater on the earth is available as frozen ice in glaciers and icebergs. This leaves less than 1% of the total water on earth for human consumption. This is available as groundwater, as surface water and as water vapour.

Hence, freshwater is a precious resource for us. The total volume of water on the earth remains constant. Water keeps on getting cycled through oceans, the air, the land and back to ocean; through a process called water cycle.

Human beings use water for a variety of purposes; like drinking, bathing and washing. Water is also used in production of various things for our use. Moreover, water is used in agriculture, industries and in electricity generation.

Increasing population has resulted in exploitation of water on an even larger scale. This has resulted in shortage of water at many places. Shortage of drinking water is a major problem in many parts of the world. Almost all the continents are facing the problem of water scarcity.

Conservation Of Water Resources

• Access to clean and adequate water is a major problem in the world. Overuse and pollution of water have made it unfit for use at many places. Sewage, agricultural chemicals and industrial effluents are often discharged into water bodies either in partially treated or untreated form. They pollute the water with various kinds of contaminants. Treatment of these effluents can help in controlling water pollution.
• Forest and vegetation cover slow the surface runoff and thus help in recharging the groundwater. Surface runoff can also be reduced by applying the methods of water harvesting.
• Canals should be properly lined to minimize the losses by seepage. Sprinklers and drip irrigation help in minimizing the use of water for irrigation and thus help in conservation of water.

NATURAL VEGETATION AND WILDLIFE

Biosphere: Natural vegetation exists only in the biosphere. The narrow zone of contact between the lithosphere, hydrosphere and atmosphere; in which life exists is called biosphere.

Ecosystem: The living beings are inter-related and interdependent on each other for survival. This life supporting system is called ecosystem.

Importance of Natural Vegetation: Vegetation provides shelter to animals and provides us with timber and many other forest produce. Plants also produce oxygen when they make food and oxygen is the gas we breathe. Plants protect soil from degradation. Plants help in recharging the groundwater.

Wildlife: Animals, birds, insects as well as the aquatic life forms comprise the wildlife. We get meat and leather from animals. Honey bees provide us with honey. Insects are the major pollinators and thus help not only the plants but also the human beings. Some animals play the role of scavengers and clean the dead remains of animals. All animals play important role in maintaining the balance in the ecosystem.

DISTRIBUTION OF NATURAL VEGETATION

Temperature and moisture determine the growth of vegetation in a particular region. Forests, grasslands, scrubs and tundra are the major vegetation types in the world.
Huge trees can thrive in areas of heavy rainfall. Thus, dense forests are present in areas which have abundant supply of water. The size and density of trees decreases with relative decrease in moisture.
Short stunted trees and grasses grow in the regions of moderate rainfall. Thorny shrubs and scrubs grow in dry areas which get low or negligible rainfall. The Tundra vegetation is found in cold Polar Regions and comprises of mosses and lichens.

• Evergreen Forests: Trees of evergreen forests do not shed their leaves at a particular time in a year. Evergreen forests are found in tropical regions which get plenty of sunshine and rainfall.
• Deciduous Forests: Trees of deciduous forests shed their leaves at a particular time in a year. Deciduous forests are found in subtropical regions which get moderate sunshine and rainfall.

CONSERVATION OF NATURAL VEGETATION AND WILDLIFE
Deforestation, soil erosion, construction activities, forest fires, tsunami and landslides are some of the factors which are causing extinction of forest and wildlife resources. Poaching is another concern which is leading to extinction of valuable wildlife.

The government has made national parks, wildlife sanctuaries, and biosphere reserves to protect the natural vegetation and wildlife.
Many awareness programmes; like social forestry and Vanamahotsava are also encouraged to conserve the wildlife and forests.
Many laws have been passed to make poaching an illegal and punishable offence. In India, killing of lions, tigers, deer, etc. have been banned.
An international convention CITES has been established that lists several species of animals and birds in which trade is prohibited. CITES stands for Convention on International Trade in Endangered Species of Wild Fauna and Flora. About 5,000 animal species and 28,000 plant species are being protected under the CITES.