Notes of Ch 17 Forests: Our Lifeline Class 7th Science

Revision Notes of Ch 17 Forests: Our Lifeline Class 7th Science

Topics in the chapter


  • Forest
  • Deforestation
  • Effect of deforestation
  • Independence of plants and animals in forest
  • Canopy
  • Food chain
  • Food web
  • Importance of forests
  • Conservation of forests

Forest

→ It is a large area of land thickly covered with trees, bushes etc.

→ It is a system comprising various plants, animals and micro-organisms.

→ It is also protect the soil from erosion.

→ It influences climate, water cycle and air quality.

→ The uppermost layer of forest is trees followed by shrubs, the herbs to the lowest layer of vegetation.

→ Different layers of vegetation provide shelter and food for birds, animals and insects.

→ The components of forest are interdependent on one another.

→ Forest keeps on growing and changing. Also forest can regenerate.

Deforestation

→ It is a process of cutting down of trees is known as deforestation.

Effect of deforestation

→ Due to deforestation the amount of carbon dioxide in air will increase, which increase the temperature of earth.

→ Deforestation cause floods because soil lost the capacity to hold water.

→ Insects, animals, birds will not get food and shelter.

→ It cause endanger lives and environment.

Independence of plants and animals in forest

→ Animals and plants depend on each other to remain alive.

→ Organisms interact with each other and their physical environment to derive energy and survive.

Canopy

→ It is the aboveground portion of a plant community or crop, formed by plant crowns.

→ In terms of forest canopy refers to the upper layer formed by mature tree crowns and including other biological organisms.

Food chain

→ It is an interdependence of organisms which shows that who eats whom is known as food chain.

→ Interdependence of producer to consumer and form of various linkages that appears as a chain is known as food chain.

Food web

→ It is a system of interdependent food chain used to represent various relationships in organisms is called food web.

Importance of forests

→ It purify air

→ It prevent soil erosion

→ Forest is noise absorbers

→ It provide timber

→ It provide shelter to the animals

→ It helps in to control floods

Conservation of forests

→ Control forest fires

→ Promote afforestation

→ Do not allow overgrazing

→ Protect wildlife

→ Social forestry

→ Establishment of national parks and bio-reserves.

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