CBSE – 7th Standard Science

Chapter 17 – Forests: Our Lifeline

Chapter 17 

Forests: Our Lifeline


  • Forest provides a home for many animals and plants.
  •  Several other trees, shrubs, herbs and grasses are found in the forest.
  • The trees were also covered with different types of creepers and climbers
  • The forest floor provides favorable conditions for seeds to germinate and develop into seedlings
  • The branches of the tall trees look like a roof over the other plants in the forest, it is called a canopy.


  • Branchy part of a tree above the stem is known as the crown of the tree they are of different types and sizes.
  • These had created different horizontal layers in the forest.
  • Giant and tall trees constituted the top layer followed by shrubs and tall grasses, and herbs formed the lowest layer.
  • Every part of the forest is dependent on the other parts.
  • If one component is removed all other components would be affected.


  • The plants help to provide oxygen for animal respiration.
  • They also maintain the balance of oxygen and carbon dioxide in the atmosphere.
  • That is why forests are called lungs.
  • Micro-organisms eat .the dead plant and animal tissues and convert them into a dark coloured substance called humus.



  • The micro-organisms which convert the dead plants and animals to humus are known as decomposers, nutrients of the dead plants and animals are released into the soil.


  • Dead animals become food for vultures, crows, jackals and insects.
  • The decaying animal dung also provides nutrients to the seedlings to grow.
  •  In this way, the  nutrients are cycled. So, nothing goes waste in a forest
  • Trees take in water from their roots and release water vapour into the air through evaporation.
  • Many people also live in the forest.
  • Some of them may belong to different tribes. Depend mostly on the forests.
  • The forest provides them with food, shelter, water and medicines.
  • Larger number of herbivores means increased availability of food for a variety of carnivores.
  • The wide variety of animals helps the forest to regenerate and grow.
  •  Decomposers help in maintaining the supply of nutrients to the growing plants in the forest.
  • Therefore, the forest is a ‘dynamic living entity’   full of life and vitality.”
  • The forest also acts as a natural absorber of rainwater and allows it to seep. It helps maintain the water table throughout the year.
  • Forests not only help in controlling floods but also help maintain the flow of water in the streams so that we get a steady supply of water.,
  •  If trees are not present, rain hits the ground directly and may flood the area around it.
  • Heavy rain may also damages the soil.
  •  Roots of trees normally bind the soil together, but in their absence the soil is washed away or eroded.
  • Forests provide us with oxygen.
  • They protect soil and provide habitat to a large number of animals.
  • Forests help in bringing good rainfall in neighboring areas.
  • We get various products from the forests surrounding us.
  • Forest is a system comprising various plants, animals and micro-organisms.
  • In a forest, trees form the uppermost layer, followed by shrubs.
  • The herbs form the lowest layer of vegetation.
  • Different layers of vegetation provide food and shelter for animals, birds and insects.
  • The various components of the forest are interdependent on one another.
  • The forest keeps on growing and changing, and can regenerate.
  • In the forest, there is interaction between soil, water, air and living organisms.
  • Forests protect the soil from erosion.
  • Soil helps forests to grow and regenerate.
  • Forests are the lifeline for the forest-dwelling communities.
  • Forests influence climate, water cycle and air quality.
  • Cutting of these forests is called as deforestation


  • The effects of deforestation are very large, such as


CBSE 7th Standard Science

CTN’s handcrafted quick & easy revision notes to help the students understand the concepts and revise the chapters.

You will also get comprehensive question bank which will not only help the student prepare for the exams, but also secure better grades and marks in their exams.

CBSE 7th Standard Science Syllabus and Revision Notes

  • Chapter 1 – Nutrients in plants
  • Chapter 2 – Nutrition in Animals
  • Chapter 3 – Fibre to Fabric
  • Chapter 4 – Heat
  • Chapter 5 – Acids bases and salts
  • Chapter 6 – Physical and Chemical Changes
  • Chapter 7 – Weather, Climate and Adaptations of Animals to Climate
  • Chapter 8 – Winds, Storms and Cyclone
  • Chapter 9 – Soil
  • Chapter 10 – Respiration in Organisms
  • Chapter 11 – Transportation in Animals and Plants
  • Chapter 12 – Reproduction in Plants
  • Chapter 13 – Motion and Time
  • Chapter 14 – Electric Current and its Effects
  • Chapter 15 – Light
  • Chapter 16 – Water: A Precious Resource
  • Chapter 17 – Forests: Our Lifeline
  • Chapter 18 – Waste water Story