Forests: Our Lifeline Class 7 Science Notes - Chapter 17


Clearing of forests and trees eventually using that land for other purposes like agriculture and other human activities. The main causes for deforestation are:
(i) agricultural expansion
(ii) livestock grazing
(iii) Illegal logging, which is cutting, processing of trees in prohibited land.
(iv) human infrastructure expansion
(v) overpopulation


Consequences of Deforestation

(i) The source of conversion of carbon dioxide to oxygen is reduced. Plants use photosynthesis to convert carbon dioxide to oxygen. This process leads to Global Warming.
(ii) Pollution increases as there is a decrease of plants, which give out fresh air to breathe.
(ii) Ground water level also gets lowered. Desertification and droughts are the results of deforestation.

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Wildlife Conservation

Conservation of forest and wildlife

  • Many NGO’s are working towards creating public awareness for conserving depleting forest cover and vanishing wildlife.
  • Central and state governments in India have set up national parks and wildlife sanctuaries to protect forests and endangered species in wildlife.

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Species is a group of populations, which are capable of interbreeding (reproducing fertile offspring).

Flora and fauna

The plants and animals observed in a specific region are referred to as flora and fauna of that region.

Biosphere Reserves

Biosphere and Biodiversity

  • Biosphere is that part of the earth in which living organisms exist and is a sum of all the ecosystems.
  • Biodiversity, refers to the variety of organisms existing on the earth, their interrelationships and their relationship with the environment.

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Endemic species

Endemic species are species of plants and animals that are exclusively found only in a particular region or area.

Wildlife Conservation Projects

(i) Biosphere Reserve- Large areas which conserve biodiversity and civilization of that region. They preserve and protect tribal groups in addition to wildlife.  Eg: Pachmarhi Biosphere Reserve.

(ii) Zoo- Wild animals are kept for research, preservation and also for public exhibition and tourism. Eg: Mysore zoo, Indira Gandhi zoological park.

(iii) National Park- Reserved habitats for both flora and fauna especially endangered species. National parks cover large areas where animals can freely move around. E.g. Gir forest national park, Periyar national park.

(iv) Sanctuary- Sanctuaries are largely protected habitats for animals. E.g. Krishna wildlife sanctuary.

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Make the World a Greener Place

Recycling of Paper

Paper is recycled so that more trees do not have to be cut down to create more paper. It is important that we conserve trees and reduce the use of paper as much as possible.

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Reforestation is restoring of the cleared or destroyed forests by planting new trees.


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  • Extinction is the dying out or death of all members of a species.
  • Human intervention (either directly or indirectly) has become the leading cause of species extinction.
  • Eg: Animals like the Dodo bird, Tasmanian wolf are extinct.

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Tiger Project

Endangered animals
Animals whose count is reducing to an extent that they might face extinction are known as the endangered animals. Eg: Giant panda, tiger. Red Data Book is a source(reference) book, keeping a record of all the plant and animals that are endangered.
Ecosystem is the region consisting of all the living plants, animals and microorganisms in an area along with non-living components such as climate, soil, river deltas, etc.


Migration is defined as the movement of organisms in large numbers from one place to another.

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Frequently asked Questions on CBSE Class 7 Science Notes Chapter 17: Forests Our Lifeline

What is ‘Virgin vegetation’?

Virgin vegetation is also known as natural vegetation. Hence the vegetation which has been grown naturally without human help is called virgin vegetation.

What are ‘Monsoon forests’?

Monsoon forests are open deciduous or partially deciduous forest of tropical regions that develops in areas with alternating seasons of heavy rainfall and prolonged drought.

What are ‘Montane forests’?

Montane ecosystems refer to any ecosystem found in mountains. Dense forests are common in areas of moderate elevations.

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