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Forest Conservation & Deforestation Notes | Study Biology Class 12 - NEET

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It is conducted by two methods

1. Protection or conservation forests : By making national park and Biosphere Reserve.
2. Production or commercial forestry : It is two types
(a) Social forestry : To grow trees and shrubs on unused farmland, road sides, rail sides, community land etc.
(b) Agro Forestry : woody species are grown in combination with herbaceous crops either at the same time or in time sequence.

Taungya system : Growing agricultural crops between rows of planted trees.

Shifting Cultivation or Jhum Cultivation : It is a major cause of deforestation. Many tribal communities practice slab and burn agriculture in tropical and subtropical regions of Asia. Africa and Oceania. This consists cutting down trees and setting them or fire and raising crops on the resulting ash called “Juming” in north eastern India.

Low lying area's covered with shallow water are called wet land's. The wet lands are transitions, zones between terrestrial and aquatic area's. 6% of the world land surface is occupied by wet lands.
Marshes : Wetlands where grass - like plants dominate.
Swamps : Wetlands where trees or shrubs dominate.
Riverine forest : Periodically Flooded forest found in lowland along streams.
Mangrove is a salty water swamp.


The degradation of natural resources can occur, not just by the action of pollutants but also by improper resource utilization practices.

(i) Soil erosion and desertification : The development of the fertile top-soil takes centuries. But, it can be removed very easily due to human activities like over-cultivation, unrestricted grazing, deforestation and poor irrigation practices, resulting in arid patches of land. When large, barren patches extend and meet over time, a desert is created. Internationally, it is particularly due to increased urbanization.

(ii) Water logging and soil salinity : Irrigation without proper drainage of water leads to water logging in the soil. Besides affecting the crops, water logging draws salt to the surface of the soil. The salt then is deposited as a thin crust on the land surface or starts collecting at the roots of the plants. This increased salt content is inimical to the growth of crops and is extremely damaging to agriculture. Water logging and soil salinity are some of the problems that have come in the wake of the Green Revolution. This leads to 'sem' problem in many canal irrigated areas of India.

Deforestation :
Deforestation is the conversation of forested areas to non-forested ones. According to an estimate, almost 40% forests have been lost in the tropics, compared to only 1% in the temperate region. The present scenario of deforestation is particularly grim in India.

At the beginning of the twentieth century, forests covered about 30% of the land of India. By the end of the century, it shrunk to 19.4%, whereas the National Forest Policy (1988) of India has recommended 33% forest cover for the plains and 67% for the hills.

How does deforestation occur? A number of human activities contribute to it. One of the major reasons is the conversion of forest to agricultural land so as to feed the growing human population. Trees are axes of timber, firewood, cattle ranching and for several other purposes.

Slash and burn agriculture, commonly called as Jhum cultivation in the north-eastern state of India, has also contributed to deforestation. In slash and burn agriculture, the farmers cut down the trees of the forest and burn the plant remains.

The ash is used as a fertilizer and the land is then used for farming or cattle grazing. After cultivation, the area is left for several years so as to allow its recovery. The farmers then move on to other areas and repeat this process. In earlier days, when Jhum cultivation was in prevalence, enough time-gap was given such that the land recovered from the effect of cultivation. With increasing population, and repeated cultivation, this recovery phase is done away with, resulting in deforestation.

What are the consequences of deforestation? One of the major effects is enhanced carbon dioxide concentration in the atmosphere because trees that could hold a lot of carbon in their biomass are lost with deforestation. Deforestation also causes loss of biodiversity due to habitat destruction, disturbs hydrological cycle, causes soil erosion, and may lead to desertification in extreme cases.

Reforestation is the process of restoring a forest that once existed but was removed at some point of time in the past. Reforestation may occur naturally in a deforested area. However, we can speed it up by planting trees with due consideration to biodiversity that earlier existed in that area.

Case study of People's Participation in Conservation of Forest

People's participation has a long history in India. In 1731, the king of Jodhpur in Rajasthan asked one of his ministers to arrange wood for constructing a new place. The minister and workers went to a forest near a village, Khajadli inhabited by Bishnois, to cut down trees.

The Bishnoi community is known for its peasful co-existence with nature. The effort to cut down trees by the kings was thwarted by the Bishnois.

A Bishnoi women Amrita Devi showed exemplary courage by hugging a tree and daring king's men to cut her first before cutting the tree. The tree mattered much more to her than her own life.

Sadly, the king's men did not heard to her pleas, and cut down the tree along with Amrita Devi.
Her three daughters and hundreds (total 363 peoples of other Bishnois followed her, and thus lost their lives saving trees.

Nowhere in history do we find a commitment of this magnitude when human beings sacrificed their lives for the cause of the environment. The Government of India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for individuals or communities from rural areas that have shown extraordinary courage and dedication in protecting wildlife.
Government of India instituted Indra Gandhi Priydarshni; Vraksh Mitra Award for forest conservation.

You may have heard of the Chipko Movement of Garhwal Himalayas. In 1974, local women showed enormous bravery in protecting trees from the axe of contractors by hugging them. People all over the world have acclaimed the Chipko movement.

Realising the significance of participation by local communities, the Government of India in 1980s has introduced the concept of Joint Forest Management (JFM) so as to work closely with the local communities for protecting and managing forests. In return for their services to the forest, the communities get benefit of various forest products (e.g., fruits, gum, rubber, medicine etc.) and thus the forest can be conserved in a sustainable manner.




The International Union for Conservation of Nature and Natural Resources. (Switzerland)


The World Wildlife Fund.


India Board for Wildlife.


The Bombay Natural History Society.


The Wildlife Preservation Society of India.


Central Pollution Control Board.


International Biology Programme.


Man and Biosphere Programme.


United Nation Environment Programme.


National Museum of Natural History.


United Nations Development Programme.


Biosphere Reserve Programme.


Zoological Survey of India.


Botanical Survey of India


Central Arid Zone Research Institute, Jodhpur.


Convention and International Trade in Endangered Species of Wild Fauna and Flora. (1976)


Forest Research Institute, Dehradun.


Wild Life Institute of India, Dehradun.


United Nations Educational Scientific and Cultural Organization.

28th February

 Science Day

21st March

   World Forest Day

22nd April

    Earth Day

5th June

 World Environment Day

7th July

  Van Mahotsav Day

11th July

 World Polulation Day

16th September

 World Ozone Day

3rd October

  World Animal Day

4th October

World Habitat Day

1st Week of October

  Wild life week

2nd December

 National Pollution prevention day or National environment day

3rd Decern ebr

 World Conservation Day

22th May

 World Biodiversity Day


MIC [Methyl Isocyanate] was released in Bhopal gas tragedy on 3rd December 1984. which is used in the production of "Savin" insecticide in Union Carbide.
Tetraethyl lead and tetramethyl lead are formed by combustion of petroleum. They are known to hamper haemoglobin formation.
The disease produced by use of lead polluted water is called as plumbism.
Lead caused nervousness and anaemia in human beings. It also damages kidney.
Lead concentration in blood is considered alarming if it is 10 μg/500 ml.

Common dust disease is known as Pneumoconiosis.
Disease due to cotton dust in testile workers is - Lung fibrosis or Byssinosis.
Disease due to coal dust - Anthracosis.
Disease due to asbestos dust - Asbestosis.
In stone grinders disease due to silica dust - Sillicosis.
In iron mill disease due to iron dust - Siderosis.
Cadmium causes anaemia, hypertension, damage to liver and kidneys. In Japan it caused bone softening or skeleton deformitcis called Itai-Itai disease or Ouch-Ouch.

Stone leprosy is caused due to acid rain because due to acid rain outer surface of metals, marbles and stone gets destroyed.

Blue Baby disease : This disease is caused by the high amount of nitrate in water. It is also known as Methaemoglobinaemia or cyanosis.

Hypertension and Uremia : Caused by Copper.

Arsenic : It causes black-foot disease and poisoning in fodder plants which are eaten by live stock and causes their death.

Fluorides : The higher concentration of fluorides causes chlorosis or necrosis in tips and margin of leaf (leaf lamina). The compounds of fluorine reach in the animals through the fodder and causes abnormal calcification of teeth, this is called Fluorosis.

Note : The experts hold that the maximum level of fluoride which the human body can tolerate is 1.5 parts per million (ppm). When ingested in excess over a long period of time causes "Fluorosis".

EL Nino effect : It is the process in which water of Pacific ocean get warm, in this process warm water current flow to Ecuador & Peru in between 5 to 8 years at christmas time. Effect of EL Nino is flood, drought and monsoon damage in India.

Cesium (Cs) accumulates in muscles and causes muscular pain.

Strontium-90 is radioactive element which causes Leukamia and bone cancer.

Iodine isotope-131[I131] causes damage of RBC, bone marrow, Lymph nodes and Skin cancer.

Tobacco and smoke contain seven poly cyclic hydrocarbon and Radio active Polonium-210, which is carcinogen and causes Lung cancer.
Aldehydes produce irritation in the gastrointestinal and respiratory tract.
Phenols caused damage to spleen, Kidney, liver and lungs.

D.D.T. caused Cerebral haemorrhage and malfunctioning of sexual maturtity.

Largest source of air pollution (80%) caused by automobiles in the cities i.e., CO(77.2%).Nitrogen oxide (7.7%), Hydrocarbons (13.7%), SO2, NH3, Aldehyde and Lead [in the form of Pb(C2H5)4 and Pb[(CH3)4 as antiknocking agent]. Lead is an air pollutant. Automobiles also reduce atmosphereic O2 which is utilised in oxidation.

Particulate pollutants [soot] are Carcinogenic [Cancer causing].

The particulate matter released to the atmosphere by mechanical operations include a number of trace metals contained in the flyash. Some of harmful trace metals are Antimony, Arsenic, Beryllium, Cadmium, Germanium, Lead, Mercury, Nickel, Selenium, Vanadium and Yttrium.




The National Environment (Protection) Act (NEPA) 1986 : This act clearly brings the protection of water and soil quality, and the control environmental pollutants.


The insecticide Act, 1968 : This act deals with the regulation of import, manufacture, sale, transport, distribution and use of insecticides with a view of preventing risk to human health and other organisms.


The water (Prevention and control of pollution) Act. 1974 : This act deals with the preservation of water quality and the control of water pollution with a concern for the detrimental effects of water pollutants on human health.


The air (Prevention and Control of Pollution) Act. 1981 : This act deals with the preservation of air quality and the control of air pollution with a concern for the detrimental effects of air pollutants on human health and also on the biological world.


In 1987, important amendments to the air Act.1981 were made and noise was recognised as an air pollutants.

Conference on human environment in 1972 held at Stockholm.

International Biological Programme (IBP) 1967-74.

The united Nations, conference on desertification was held in Nairobi (Kenya) in 1977 under the United Nations Environment Programme (UNEP).

Type of Lakes -
(i) Eutrophic lake - They are shallow water lakes which contain high amount of organic materials and nutrients. They have little O2 because decomposers rapidly use it up. Chironomous larva are commonly present in it. eg., Dal lake of Kashmir
(ii) Oligotrophic lakes - These are deep lakes which have less amount of organic materials and nutrient.
(iii) Dystrophic lake - Maximum amount of undecomposed organic matter is present. eg., Marshy lake.

Third pollution or land scape pollution : To make Fertile-land barren by dumping wastes. eg., ash, insustrial waste.
Incineration : Solid wastes burning in presence of oxygen.
Pyrolysis : Solid wastes burning (combution) in the absence of oxygen.
Flu gas : Gas which release of from chimnies.
Plume : Smoke which release from chimnies.
Hydro thermal vents : These are hot water springs in the deep ocean having high concentration of H2S, ocean water oxidizes H2S producing energy which is used by bacteria, Filter-Feeders (clams) eat the bacteria so that this food chain based on chemical energy.
Phytotrons : A such type of house where plants are grown in controlled environment.
Hydrocarbon : Are also known as volatile organic carbons (VOC).
Snow blindness : In human eye cornea absorbs U.V.-B radiation, and a high dose of U.V.-B radiations causes inflammation of cornea, called snow-blindness cataract.

Electronic wastes is also called e-wastes.

Ganga Action plan for controlling pollution in ganga (1985) included city :

(i) Kolkata

(ii) Kanpur.

Land of maximum wind mills - Netherland.
Largest wind will complex in India, Lamba (Gujrat)
At 50 ppm, CO converts 7.5% of haemoglobin in to carboxy haemoglobin with in 8 hours.
Maximum grean house gas released by - USA
Cotton dust is an important pollutant in Ahmedabad.

CEPHERI : An institution established in India to check pollution i.e., "Central Environmental and Public Health Engineering Research Institute" (CEPHERI).
This institution submits the measures on the basis of results of detailed survey.
NEERI : National Environmental Engineering Research Institute - Nagpur. (Environmental plannig organisation is related with NEERI)
IPCC : The "Intergovermental Panel on Climate Change".
I.A.P. :Index of atmospheric pollution prepared with the help of lichens.
I.W.P. : Index of water pollution, prepared by Daphnia, E.coli, Trout.
M.P.N. : Most probable number of E.coli in water.


The increase in the concentrations of green house gases in the in the atmosphere as affected by human activities 

Green house gases

Pre-industrial concentration - 1750 AD

Concentration in 2000 AD

Increase since ~ 1750 AD

Atmospheric life-time (years)

Carbon dioxide (C02)

280 ppm

368 ppm


5 - 200

Methane (CH4)

700 ppm

1750 ppb



Nitrous oxide (N70)

270 ppb

316 ppb



Chlorofluorocarbons (CFC - 11) + Hydroflurocarbons (HFC - 23)

0282ppt 45-260



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