Revision Notes for Class 8 Science Conservation Of Plants And Animals
Class 8 Science students should refer to the following concepts and notes for Conservation Of Plants And Animals in standard 8. These exam notes for Grade 8 Science will be very useful for upcoming class tests and examinations and help you to score good marks
Conservation Of Plants And Animals Notes Class 8 Science
CBSE Class 8 Science Conservation of Plants and Animals Chapter Notes. Learning the important concepts is very important for every student to get better marks in examinations. The concepts should be clear which will help in faster learning. The attached concepts made as per NCERT and CBSE pattern will help the student to understand the chapter and score better marks in the examinations.
CONSERVATION OF PLANTS AND ANIMALS
1. Deforestation 2. Biodiversity 3. Conservation of Forests & Wildlife
4. Biosphere Reserve 5. Threatend Species 6. National Parks and Sanctuaries
7. Red Data Book 8. Migration 9. Reforestation
POINTS TO BE REMEMBER
Deforestation : The loss or continual degradation of forest habitat due to natural or human activities.
Afforestation : Planting of trees on a large scale to regenerate forest.
Desertification : The process of conversion of fertile land into deserts due to the removal of top layer of soil.
Ecosystem : The basic unit of ecology which consists of the biotic and abiotic components.
Reforestation : It is the restocking of the destroyed forests by planting new trees.
Fauna : The community of animals in a specific region or habitat.
Flora : The plant life of particular area.
Endemic species : The species that are exclusively found in any geographical unit like a state, zone or a country or a habitat type are referred as endemic species.
Sanctuaries : The protected area which is reserved for the conservation of animals only and human activities upto a certain extent are allowed in these areas.
National Park : The large and diverse reserves to protect whole sets of ecosystem including flora, fauna, landscape and historical objects of an area are termed as national park.
Biosphere Reserve : A biosphere reserve is a unique concept which includes one or more protected areas and surrounding lands that are managed to combine both conservation and sustainable use of natural resources.
We have read in earliar classes that humans use a number of natural resources for their survival. However, as human population has been increasing at a high rate, the natural resources are also being used in greater quantity than ever before. With recent advances in science and technology, people now have a higher standard of living. As a result, there is a far great demand for the natural resources. It is for this reason that the natural resources must be 'conserved' so that there will be enough resources available for the future generations.It must be clearly understood that conservation does not mean that we have to stop the use of these resources completely. It only means that we have to use the resources wisely and judiciously. conservation is the wise and judicious use of resources. The overuse or wastage of resources would lead to imbalanaces among the various components of nature.
Aims of conservation
* To preserve the quality of environment, i.e., maintain a pollution-free environment.
*To ensure a continuous yield of useful plants, animals and materials for generations to come
Conservation of Plnats and Animals
*Importance of Forests
• Forests are natural habitat of wild animals and plants.
• Roots of trees keep the topsoil bound and prevent it from being washed away through water erosion as well as through wind erosion.
• Trees give a large amounts of water by the process of transpiration. This helps in formation of rain clouds and bringing fresh water to the earth.
• Forests help in maintaining oxygen and carbondioxide levels in atmosphere.
• Forests also act as saviour from various solar radiations.
• Forests provide raw material for paper industry.
• Forests have various protective functions like prevention of drought, protection against wind, cold, noise, radiations and even conservation of soil and water.
• Forests are important for production of timber, bamboos, food and wide variety of compounds like resins, alkaloids, essential oils, latex and various pharmaceutical products.
Forests are home to several kinds of plants and animals. The number and type of plants and animals found in a forest depends on the soil and climatic conditions of the region. For example, a type of forests called the rainforests are believed to house of millions of the species of plants and animals, some of them yet undiscovered by human beings. Rainforests cover less than 6% of the earth's total land surface, but are home for up to almost three-fourths of all known species of plants and animals.
The loss or continual degradation of forest habitat due to natural or human activities is called deforestation.
Large scale cutting of trees is called deforestation
Causes of Deforestation
Trees are cut in the forest on a large scale to clear the land for some useful purposes listed below.
• Procuring land for agricultural use.
• Procuring timbers for building houses, roads, railway tracks, dams, etc.
• Procuring land for setting up industries and mining.
• Procuring land for setting up special economic zones (SEZ).
• To obtain forest products like wood, food, rubber, honey, resins, etc.
Natural Causes of deforestation
(i) Forest fire (ii) Drought
CONSEQUENCES OF DEFORESTATION
• Flood and Droughts : Trees check the flow of rainwater. When mountain slopes and uplands are deforested, the water rushes down and causes rivers to overflow and flood in lower lands. The silt carried by the water from denuded slope chokes rivers and aggravates the problem of flooding. Siltation of rivers not only causes floods, but harms fisheries and waterways.
Deforestation can lead to droughts as well. Forests hold water and release it slowly. When they are cut down, the water rushes down very fast, and the uplands, especially, are deprived of water soon after the rains. By holding water and improving the water-retaining capacity of the soil, forests also help recharge groundwater. In India, deforestation of the Himalayas has changed perennial streams into seasonal streams, which run out of water soon after the monsoon. It has causes an acute shortage of water even in Cherapunji (in Meghalaya), which is one of the wettest place in the world.
• Induces More Soil Erosion : The top soil is easily carried away by wind or water in the absence of tree cover, thus increases soil erosion. The soil thus loses its fertility. Gradually a fertile land gets converted into a desert. It is called desertification.
• Imbalance of Atmospheric Gases
• Change in Climate : Most (over 95%) of the warter absorbed by trees from the soil is released into the air during transpiration. This increases rainfall and brings down temperature in the region around a forest. Naturally, when a large area is deforested, there are changes in the climate of that area.
Deforestation can also lead to global changes in the weather pattern by increasing the amount of carbon dioxide in the air. This is because trees absorb carbon dioxide from the air. Cutting down trees means a loss of this service. Also, when trees are used as fuel, the carbon locked in them is released into the air as carbon dioxide. Even when they are used as timber or for other purposes, the branches and leaves rot and carbon dioxide is released into the air. It is estimated that the destruction of tropical forests alone accounts for more than 25% of the carbon dioxide released into the air annually.
Global warming is believed to be causing uncharacteristically frequent and severe cyclones, floods, droughts and forest fires across the world. It is also affecting plants and animals in the polar region. According to one study, for example, the number of emperor penguins in the Antarctic has reduced alarmingly due to global warming.
• Natural Calamities : Deforestation increases the chances of natural calamities such as floods, droughts, landslides, cloudburst, etc.
• Destruction of Natural Habitat : Cutting of trees on a large scale destroys the natural habitat of several plants, animals and microorganisms. This disturbs the ecological balance in nature. Several food chains and food webs get affected due to this imbalance.
The destruction, degradation or modification of forests endangers the survival of the organisms in it. It may even cause some to become extinct (disappear) from a region, a country or the world.
Habitate destruction often has a direct impact on the lives of the people living near forests. It makes wild animals stray into villages and destroy crops, kill livestock or even attack people. It also disturbs natural pollinators, like birds, bats, butterflies and bees. The pollinators move away to other areas and stop pollinating the crop and fruit plants cultivated near forests.
• Scarcity of Forest Products
• Reducing Water Table : In the absence of tree cover, rainwater cannot infiltrate into the ground to recharge the aquifer. It leads to the lowering of ground water level in the absence of replenishment
STEPS FOR THE CONSERVATION OF FORESTS
• The people living in cities, villages, forests, etc., must be educated about the importance of forests through Government and Non-Government social agencies. As a matter of fact, people must realise that cutting a tree is a crime like killing a human being or an animal.
• The forst department must be highly organised. They should see to it that no illegal felling of trees take place and the criminals must be brought to justice.
• As we need wood for various purposes, we cannot altogether stop cutting the forests. Therefore, Forest Department must earmark the trees in a given forest, so that only dead or very old trees are cut. Furthermore, for cutting each tree, two or more tree saplings should be planted so that in 10 years or more they grow into fully grown trees.
• As the forests provide grass for the domestic animals, people living around the forest let their animals in it for grazing. This should be altogether stopped. It is because the grazing animals, especially the goats and the sheep uproot the grass. This leads to soil erosion. Instead, the grass should be cut manually and then fed to the animals. Furthermore, the grazing animals trample the young saplings, thereby, slowing down the growth of trees.
• In summer, the grass in the forest is very dry. Any spark can set it on fire. Thus, the people living in the forest must be taught not to leave uncovered fire or throw butts of burning cigarettes or "bidis" carelessly in the dry grass. Any forest fire leads to large economic loss and makes the land infertile.
• Timberwood should be used only where it is absolutely necessary. For example, doors, windows, chairs, tables, etc., can be easily made from plastics and they are durable like wood.
• Large amounts of wood and grass are used in the manufacture of paper. The wood and grass are converted into pulp by chemicals. The pulp is then converted into paper by the use of machines. The paper so produced finds use in printing books, newspapers, copy books and for packaging. Every year vast tracts of forest are cut to prepare paper. This leads to deforestation. To reduce the deforestation we must recycle the waste paper, by again converting it into pulp. This no doubt reduces the quality of paper, but can be used for packaging. Furthermore, in order to reduce deforestation, the cleared forest land should be replanted with fast growing grass and bamboo. This will meet future requirements of paper industry. Even the old cotton clothes should be collected and sent to paper mills for making pulp and the paper.
CONSERVATION OF FORESTS
The maintenance and upkeep of forest is called forest conservation. The following steps should be undertaken to conserve them.
1. Massive afforestation work should be undertaken to cover large areas of land with appropriate trees.
2. Felling of trees in the forest should be banned.
3. Every piece of barren land should be planted with trees.
4. Weeds, damaged trees, crowded trees, diseased trees, etc. should be removed.
5. Forest fire must be prevented.
6. Forest nurseries should be established on a large scale.
(A) Give answer of following questions :
1. What is soil erosion ?
2. How deforestation affect increasing concentration of CO2 ?
3. How deforestation affect Land-slides and floods ?
4. How increased carbondioxide concentration is responsible for increase in temperature of earth ?
5. Define flora.
6. How building houses and factories affect deforestation ?
7. Mention the effect of overgrazing on biodiversity.
8. What is importance of forests ? Write a short note on it.
9. Mention main causes of deforestation.
10. Write consequences of deforestation.
(B) Fill in the blanks :
1. Restocking of the destroyed forests by planting new trees is called ...................
2. ...................act as saviour from various solar radiations.
3. Forest helps in maintaining oxygen and ................... level.
4. Loss of water in the form of water vapour through stomata of green leaves is called ...................
5. The animals found in a particular area called ...................
(C) Fill out the true and false statements from following :
1. The natural causes for the destruction of forests are draughts, floods, storms and forest fires.
2. About 40% of the wood used in the world every year goes into making paper.
3. The Thar desert in the north west of india is an example of nature made desert.
4. Deforestation is an important cause of increase in global temperature.
5. Forests are natural habitat of wild animals and plants.
Ans. 1. T 2. T 3. F 4. T 5. T
Biodiversity or Biological Diversity
If you look around yourself, you may get to see several different kinds of plants and animals. A typical neighbourhood park may be home to a variety of flowers, each differing in size, shape, colour, and smell. The kind of trees found here could range from big trees such as the banyan tree to small bushes that may have been planted to border the pavement.
Biodiversity refers to existence of a wide range of different types of organisms in a given place at a given time.
Variety of life on earth and variability among living organisms.
Variety of life forms and habitats found in a particular area.
Uses of Biodiversity
1. Source of food and improved varieties : Biodiversity is used to modern agriculture in three ways as a source of
(a) New crops (b) Material for breeding improved varieties (c) New biodegradable pesticides.
2. Drugs & Medicines : e.g. Morphine : Papaver somniferum [Analgesic], Quinine- Chincona ledgeriana [Treatment of malaria], Taxol- Taxus brevifolia [Anticancer drug].
3. Aesthetic and cultural benefits : e.g. Ocimum sanctum- Tulsi, Ficus religiosa- Pipal, Prosopis cineraria- Khejri.
4. Ecosystem services
Project Tiger : 'Project Tiger' is one of the successful operations for conserving wildlife in India. There were about 40,000 Bengal tigers in 1910. There was a sharp decline in their numbers to 1827 in 1972. The main reasons for the extinction of tigers are hunting, deforestation and taming of rivers for human needs. Realizing this decline, a project named 'Project Tiger' was initiated in 01 April 1973. The project was funded by the World Wide Fund for Nature.
The project focussed on protecting tiger habitats by creating sanctuaries and extending the existing ones. Under this project, there are 18 tiger reserves in India.
1. Jim Corbett National Park (Uttaranchal)
2. Periyar National Park (Kerala)
3. Ranthambore National Park (Rajasthan)
4. Kanha National Park (Madhya Pradesh)
5. Sariska National Park (Rajasthan)
6. Sunderban National Park (West Bengal)
Species : A group of population which are capable of interbreeding.
This means that the members of a species can reproduce fertile offspring only with the members of their own species and not with members of other species.
Endemic Species : Those species of plants and animals which are found exclusively in a particular area.
Plant and animal species confined to specific geographic areas are called endemic species.
Sal, Wild mango, Bison, Indian giant squirrel and flying squirrel are endemic species in Pachmarhi Biosphere Reserve.
Some Endemic Species of India
1. Lion-tailed Macaque (Western Ghats) 2. Malabar Parakeet (Malabar region)
3. Nilgiri Langur (Nilgiri hills) 4. Nilgiri Tahr (Nilgiri hills)
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