12th Class Biology Biodiversity Conservation And Wild Life Conservation


Category : 12th Class

It may be defined as the most efficient and most beneficial utilization of the natural resources. Conservation is also defined as the rational use of the environment to provide a high quality of living for the mankind.

Aim of conservation : The true aim of conservation, thus, includes.

(1) To insure the preservation of a quality environment that considers aesthetic, recreational as well as product needs.

(2) To insure a continuous yield of useful plants, animals and materials by establishing a balanced cycle of harvest and renewal.

Living resource conservation has three specific objectives

(1) To maintain the essential ecological processes and the life support system : This system has five elements (air, water, land, flora and fauna) which are interconnected, interrelated and interdependent; deterioration in one inevitably affects the other four elements.

(2) To preserve the biological diversity : It includes two related concepts genetic diversity and ecological diversity. The genetic diversity is the amount of the genetic variability among individuals of a single species (intraspecific genetic variability) as also between species (interspecific genetic variability). The ecological diversity means the species richness. It is the number of species of the flora and fauna found in a region (for example, India has about 45,000 species of plants and about 65,000 species of animals).

(3) To ensure that any utilization of the species and ecosystems is sustainable : In fact, natural resources may be conserved by efficient utilization which requires a proper balance between the supply and demand. Sustainable utilization means planned utilization so that a continuous yield of the useful plants, animals and materials may be obtained.

The conservation of the following resources is necessary

(1) Minerals : Minerals are largely nonrenewable inorganic resources that are presently mined from lithosphere. Availability/distribution is quite unequal Malayasia and Indonesia are rich in tin, tungsten and manganese but deficient in molybdenum. North America has abundant molybdenum but little tin, tungsten and manganese. South Africa has rich deposits of gold, platinum and uranium but little iron and silver. India has abundant iron, manganese, dolomite, chromite and mica but is deficient in lead, potassium, phosphorus, nickel, copper, silver and gold. Phosphate rocks have recently been discovered in Jawar Kota in Rajasthan. Mineral resources of scarce elements (e.g., silver, copper, mercury, tungsten) are liable to be exhausted within next 20-100 years. With continued use even plentiful minerals will become scarce and hence expensive, e.g., iron, aluminium.

(i) Degradation of environment : Every step of mineral extraction, processing, refinement and disposal causes degradation of environment.

(a) Mineral processing releases a number of pollutants into air. It also produces a number of wastes which bring about water and soil pollution.

(b) Mining not only damages the land, it also pollutes soil water and air.

(c) Mine dust destroys nearby vegetation and makes the soil barren. It is called mine spoil.

(ii) Conservation of minerals

(a) Reuse : An article can be reused several times, e.g., 16-17 times a glass bottle. Life of a machine/article can be prolonged with small care. However, all products cannot be reused.

(b) Low waste : Use and throw tendency should be checked where a durable and repairable article is concerned. Other points of wastage should be checked and wastage controlled.

(c) Manufacturing waste : It should not be thrown but reprocessed to be used in other industries. 

(d) Substitution : Scarce metals which can be replaced by more abundant metals, e.g., copper in electric wires with aluminium, metallic pipes with plastic pipes. Plastics, ceramics and high strength glass fibres are being used in place of steel, tin and copper in many industries.

(e) Smaller articles : Smaller and sleeker articles should be made wherever feasible.

(f) Recycling : A number of metals can be recycled through reprocessing, e.g., gold, lead, nickel, steel, copper, aluminium, zinc. Recycling and reuse reduce pressure on mining and processing industries besides energy consumption and pollution. However, some minerals are lost during use, e.g., zinc, lead, chromium in paints.

(2) Forests : Forests are extensive self-sustained wooded tracts of land with abiotic community predominated by woody vegetation consisting of trees and shrubs with a close canopy. Woodland is closer to human habitation, possesses open canopy and is managed and maintained by human beings. Forests contain 90% of the terrestrial biomass. Forestry is branch of science which is connected with establishment, protection, management and exploitation of forests. Silviculture (= sylviculture) is a branch of forestry connected with cultivation and breeding of forest plants.


Forest cover in India


Area (Sq.km)

% Geographic area


Dense forests (> 40% canopy cover)




Open forests (10-40% canopy cover)




Mangrove (< 10% canopy cover)








Scrub (< 10% canopy cover)




Nonforest (Other Land Use)








(i) Forest functions : Forests have three types of function :

(a) Productive functions (Economic Uses) : Forests provide a number of articles of economic use, e.g., wood, fruit, resins, alkaloids, essential oil, latex, pharmaceuticals.

(b) Regulative functions : They regulate global biogeochemical cycles, particularly carbon and water, check floods and drought by absorption, storage and release of water etc.

(c) Protective functions (Ecological functions) : They provide protection from excessive cold, excessive heat, drought, noise, radiations and smells besides providing shelter and conserving water and soil.

(ii) Economic uses

Wood consumption is estimated at  \[3-2\] billion \[{{m}^{3}}.\text{ }46%\] of wood is used in industry while 54% is consumed as fuel wood. Consumption of fuelwood is low in advanced countries (16%) while it is high in other countries \[(75-80%).\] Larger pieces of wood are used in timber. After timber, the major industrial consumer of wood is paper industry consumes the maximum amount of bamboo.

(iii) Ecological uses

(a) Protection of land : Plant cover protects soil from drastic changes in temperature, action of wind, action of rain drops, holding soil, preventing landslides and making the soil spongy as well as fertile.

(b) Climate : Moderating and moistening effects.

(c) Frequency of rainfall : Increases. Atmospheric humidity becomes high.

(d) Pollution : Forests reduce atmospheric pollution absorbing gases and collecting SPM.

(e) Shelter : To wild animals. Over 40 million tribals and villagers live in forests. The number of cattle grazing in forests is 200 million.

(iv) Retention of subsoil water : Plant litter and humus prevent run-off, hold water like a sponge and allow percolation resulting in perennial fresh water through springs.

(v) Deforestation : It is removal, decrease or deterioration of forest cover of an area. In 1900, forests occurred in 7000 million ha which were reduced to 2890 million ha in 1985 and about 2400 million ha in 2000. Tropical forests have come down from 1600 million ha to 938 million ha. In India, one third of the land was covered by forests in late nineteen thirties. In 1951 it was only 23%.

Causes : (a) Jhuming (b) Hydroelectric projects (c) Forest fires (d) Human establishments (e) Overgrazing (f) Requirement of wood (g) Quarrying and mining.

(vi) Effects

(a) Shrinking fuelwood : In Himalayas a woman spends half day on collecting fuel. In India, availability of fuel-wood is 58 million \[{{m}^{3}}/yr\] against requirement of \[300\text{ }million\text{ }{{m}^{3}}.\]

(b) Reduced timber : There is decreased availability of timber and other farm products.

(c) Change in climate : Deforestation results in reduced rainfall, increased drought, hotter summers and colder winters.

(d) Global warming : Deforestation increases atmospheric \[C{{O}_{2}}\] content by releasing carbon stored in organic matter and reduced primary productivity.

(e) Rainfall : Amount and periodicity of rainfall decreases. In drier areas deforestation, therefore, leads to desertification or formation of desert.

(f) Drought : There is very little water in rivers during dry season causing drought.

(g) Loss of biodiversity and germplasm etc.

(vii) Conservation and management of forests : Forests cover has to be increased to reverse the effect of past deforestation. For this sustained efforts are made for reforestation and afforestation. Tree plantation movement or Van Mahotsava is being carried out in India since 1950 where by both government and private agencies perform tree plantation during July and February every year. Conservation of forests aims at management of forests in such a way as to maintain them at optimum form and derive optimum sustainable benefit for present as well as future generations. Two major strategies are adopted.

(a) Production or Commercial forestry : It is plantation of useful trees and shrubs for meeting the commercial requirements without causing any undue demand on the natural forests. It is of three types – social forestry, agroforestry and production plantation.

(b) Protection or Conservation forestry :

  • Degraded forests are mended through sylviculture practices. The forests are allowed to recoup before allowing its exploitation.
  • Certain forests included under sanctuaries and national parks are not allowed to be exploited.
  • Well stocked and mature forests are exploited scientifically.
  • Prevention of scraping and Litter removal.
  • Advanced silviculture.
  • Pesticides.
  • Fire fighting equipment.
  • Census.
  • Economy in extraction and use of timber.
  • Sustained yield block cutting : Cutting is allowed only in nonvulnerable forests at a rate which is equal to their regeneration capacity.
  • Chipko movement : It is movement initially meant for protecting trees but now meant for preservation of environment including habitat and wildlife.

(viii) Other forms of forestry

(a) Social forestry (Started in 1976 by NCA) : Raising quick growing multipurpose plants in common village lands for meeting requirement of fodder, firewood and small timber.

(b) Urban forestry : It is plantation of fruit, flower and shade bearing plants in urban areas to reduce pollution and ultimate yield of wood.

(c) Production plantation : It is growing of industry required trees on specific, either fallow or free grazing lands. Production plantation decreases pressure on real forests.

(d) Reserve forests : They are forests grown over ecologically fragile areas where our water regimes are not located. Felling of trees and grazing are not allowed.

(e) Agroforestry : It is plantation of multipurpose trees/shrubs/horticulture plants/grasses alongwith crops for stabilising soil, meeting the need of fodder, fruit and timber of the community. It is of three types – agri-silvicultural, agri-pastoral and agri-silvi-pastoral.

(3) Grasslands (Rangeland) : They are biomes dominated by grasses and herbs (especially leguminous). Grasslands provide forage to cattle and support wildlife based on grazing food chain. Tall grasses are used in thatching and as fuel. Grasslands are quite stable because highly branched fibrous root systems hold the soil particles firmly and prevent soil erosion. They are, however, prone to invasion by trees and shrubs as well as desertification. The total area under grass cover is about 18% of total land in India. Therefore, the area available for grazing in India is roughly 37% (19% forested + 18% grassland).

(i) Grassland degradation : Grasslands have been put to three types of pressures.

(a) Overgrazing : At one time in the history of human civilisation, cattle were reared in large number. The number continues to be high. For example in arid and semiarid areas of India, the number of grazing animals is 2-10 times higher than their grasslands can support.

(b) Erosion : Overgrazing denudes the soil of plant cover. Trampling by cattle decreases soil porocity. The exposed hardened soil undergoes erosion by wind and water. Wind erosion is more common where drought conditions prevail for long periods. It causes desertification or conversion of once fertile land into desert.

(c) Conversion : Overpopulation and pressure to raise agriculture yield for feeding it. As a result several grasslands with fertile soils have been converted into agricultural lands, e.g., North American prairies. The pressure on remaining less fertile grasslands increases for feeding cattle.

(ii) Grassland management

(a) Grazing should be limited to only that number of animals which can be comfortably supported by a piece of grassland.

(b) Removal of tree seedlings, bushes, shrubs and weeds which tend to reduce productivity of grasslands.

(c) Occasional seeding with high yielding leguminous herbs for maintaining soil fertility.

(d) Grasslands should be closed to grazing when new plant growth is to take place, like rainy season.

(e) A grassland should be divided into blocks with each block be allowed to be grazed on rotational basis. This allows other blocks to recover.

(f) Reducing loss of soil and water from the grassland by contour bunding.

(g) Occasional controlled burning of dried mulch to promote release of nutrients and prevent growth of tree and shrubs.

(4) Soil erosion and Soil conservation : Top soil is the vital part of the soil and serves as the chief source of nutrition for plants (feeding zone). Loss or disturbance of top soil by natural agents like water, wind, gravity or ice is called soil erosion.

Soil erosion has been called ‘creeping death of the soil’ by Rama Rao.

Soil erosion is of two types :

  • Geological or Natural erosion : It is caused by nature.
  • Accelerated or Artificial erosion : It is caused by man and animals.

(i) Types of soil erosion

(a) Water erosion : It is caused by fast running water or by continuous heavy rain. It may be :

  • Sheet erosion : Due to heavy rain, top fertile soil is removed in the form of thin sheet.
  • Rill erosion : Fast running water cut stream or groove like structure in soil.
  • Gully erosion : On steep slopes, fast running water cuts the soil deep and form channel like structure called gullies.
  • Rparian erosion : During floods fast running water cut off the margins of river.

Due to heavy rains the minerals are also lost from top soil and soil becomes less fertile.

(b) Wind erosion : Soil erosion by wind is common in dry places and most servere in arid regions where soil is chiefly sandy and the vegetation is poor or even absent.

The wind throws away smallest soil particles into air where they get suspended giving a dusty appearance to the air. It is called suspension. By this method the soil particles are transported to longer distance.

(c) Land slide or Slip erosion : The hydraulic pressure caused by heavy rains and gravitational force cause the fall off the rocks in hilly areas.

(d) Overfelling (Deforestation) and Overgrazing erosion : These process reduce vegetation thus make the soil surface open for erosion (sheet erosion).

(ii) Soil conservation : Prevention of soil erosion is called as soil conservation.

Methods of soil conservation

(a) Strip copping : Crops are arranged in bands or strips to check the flow of water.

(b) Crop rotation : Crop rotation is the method of alternative sowing of leguminous and cereal crops (wheat , maize). The rotation of crops can be planned depending upon the climatic conditions, type, slope and properties of soils.

Such crops which check soil erosion should be sown during the rainy season. Legumes are useful in rotation of crops because of having nodulated roots. Soil fertility is usually maintained in the field by rotation of crops. The minerals which are consumed by cereal crop in first year are again supplied by leguminous crops in the second year.

(c) Reforestation or Afforestation : Growing of forest trees is most effective in controlling soil erosion. Afforestation also helps in prevention of floods. Indiscriminate felling of trees have resulted in the formation of extensive ravines along Yamuna and Chambal area. The Government of India has introduced the festival of ‘Van Mahotsava’. In this festival planting of trees is done on open waste land.

(d) Terracing : Hilly slopes are divided into small flat fields called as terraces to check the flow of water.

(e) Contour farming : It is the oldest method in low rain fall area. Field is divided in furrow and ridges. Ridges at same level called as contour.

(f) Green manuring : Basically its practice is meant for increasing soil fertility but it also checks soil erosion.

(g) Dry farming : A practice for cultivation of crops in low and moderate rainfall areas.

(h) Mulching : Basal plants parts are used to make a soil cover which help in moisture conservation.

(5) Water resources : Three fourth surface of earth (71% of total) is covered by oceans which contain 97.5% of total water. It is marine water with about 3.5% salt content. Only 2.5% water is fresh water which occurs on land. Most of this water (1.97%) occurs as frozen ice caps and glaciers. 0.5% water (fresh water) occurs as ground water. Rivers and lakes contain 0.02%, soil 0.01%, while atmosphere possesses 0.001% of water as vapours.

Fresh water is the major renewable resource in terrestrial habitats being essential component of all living beings, a habitat for several organisms, determinant of vegetation and climate, floods and droughts which also has a number of human uses.

(i) Problems related to water resources

(a) Nearly 40% of human population resides in arid and semi arid areas where most of time, energy and efforts are spent in procuring water for domestic and agriculture use.

(b) At most of the other places more water is withdrawn from surface and subsurface reservoirs than their recharging. As a result many wetlands have dried up. Ground water is becoming scanty at many places.

(c) Supply of fresh water to urban and industrial areas has always been a problem because of the huge amount involved. The average consumption of fresh water per person in modern society is \[350-700\] litres per day. Further, several industries consume large quantities of fresh water. The disposal of used water is still another problem. As a result there is a great amount of misuse and abuse of fresh water.

(d) Excessive irrigation in arid/semiarid areas increases soil salinity.

(e) Over-withdrawal of ground water in coastal regions results in movement of saline water from sea in underground aquifers, resulting in spoilage of water quality.

(f) Deforestation, especially in the hilly areas has reduced water absorption, storage in catchment areas, greater incidence of soil erosion and floods during rainy season. At other times the water supply is very little.

(ii) Conservation of water resources : A number of measures are required for optimum utilisation and conservation of fresh water resources.

(a) Rainwater harvesting : Surface storage and recharging of groundwater should be carried out.

(b) Afforestation : It helps in preventing soil erosion, reduces surface run off, retains water and protects water sheds for continued water supply.

(c) Industry : Wastage should be reduced. Waste water can be recycled.

(d) Domestic water supply : Wastage should be reduced. Waste water should be treated and used in irrigation and other purposes.

(e) Irrigation : Assured irrigation is available to only 40% area as compared to over 90% in advanced countries. There is a lot of wastage of agriculture water because only 50% of water supplied to soil is useful, the rest goes waste. Bricklining of irrigation channels and sprinkling technique of irrigation are recommended to save water.

(iii) Management of water resources

(a) Dams and Reservoirs : They can be constructed to control floods and ensure round the year supply of water besides generation of electricity.

(b) Desiltation : Dredging and desiltation of water bodies should be undertaken regularly to prevent decrease in capacity for storage. \[\to\]

(c) Desalination : Sea water and saline underground water can be converted into fresh useful water through desalination.

(d) Canals : They are made to carry water in arid and semiarid area.  

(6) Fisheries : Fishes are also one of the important biotic resources and are greatly valued by man as food. Unfortunately, in the last few year fish fauna of our inland waters has greatly deplected on account of overexploitation and pollution of natural waters due to sewage and industrial wastes. It is therefore, necessary that these colourful creatures of our aquatic environment should be preserved. Fishery managers have developed many techniques to improve fish habitats. Some are :

(a) Large, artificial fielding reefs in the offshore waters of the oceans and freshwater lakes to provide hiding places and additional food which attracts the fish.

(b) Spawning channels to replace vital spawning areas destroyed or no longer accessible.

(c) Fix toxicants to destroy undesirable fish populations and restore the balance in favour of the game or commercial fish.

(d) Weed control.

(e) Fertilization and artificial enrichment.

(f) Various in-stream devices to make pools, provide cover, wash out slit, etc.

(g) Aeration and recirculation of lakes and reservoirs.

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