Class 7: Forests - Our Lifeline

Forests – Our Lifeline

Introduction and Role of Forests

1. Why did people object to cutting the forest for setting up a factory?
   People objected because forests act as:
   1. Green lungs (they give us oxygen).
   2. Water purifying systems (they help in cleaning and storing water).
   3. Home for many plants and animals.
   4. They help in keeping the balance of nature.
2. Why are forests called green lungs?
   1. Forests have many green plants.
   2. Plants take in carbon dioxide and release oxygen during photosynthesis.
   3. This oxygen is used by animals for breathing.
   4. Thus, forests act like lungs for the Earth.

Visit to the Forest

3. Why did Tibu ask the children to keep quiet in the forest?
   Because noise can disturb the animals living there, and animals give warning calls when disturbed.
4. What is a forest canopy?
   The branchy part of tall trees that looks like a roof over shorter plants is called canopy.
5. What is the difference between Crown and Canopy?
   1. Definition:
   Crown is the branchy part of a single tree above the stem, while Canopy is the roof-like cover formed by the crowns of many trees.
   2. Scope:
   Crown is about one tree only, while Canopy is about many trees together ir a forest area.
   3.Appearance:
   Crown looks like one tree's umbrella, while Canopy looks like a big green roof made by many umbrellas together.
   4. Level/Layer:
   Crown is part of an individual tree, while Canopy is the top forest layer formed by tall trees.
   5. Effect on light and rain:
   Crown blocks light and rain only under that single tree, while Canopy strongly reduces light and slows rain over a large area, keeping the forest floor cool and moist.
   6. Measurement:
   Crown is measured for one tree (size/shape of that tree's top), while Canopy is measured for an area (how much of the sky is covered by tree tops in that place).
   
6. What are understoreys in the forest?
   The different layers of vegetation in a forest below the canopy are called understoreys. They include:
   1. Tall trees (top layer).
   2. Shrubs and tall grasses (middle layer).
   3. Herbs and small plants (lowest layer).
7. Name some plants that the children saw in the forest.
   Sal, teak, semal, sheesham, neem, palash, fig, khair, amla, bamboo, and kachnar.
8. Where do new trees in the forest come from?
   New trees grow from the seeds produced by plants and trees. Forest floor provides favourable conditions for seeds to germinate and grow.

Forest Products

8. List some products we get from forests.
   Plywood, fuel wood, paper, boxes, matchsticks, furniture, gum, oils, spices, fodder, medicinal plants, sealing wax, honey, and timber.
9. Fill in the blanks (Plants and their products):
   - Gum → Babool
   - Timber → Sheesham
   - Medicinal → Neem
   - Oil → Sandalwood

Food Chain and Food Web

10. What is a food chain? Give an example from the forest.
    A food chain shows how energy passes from one organism to another.
    Example: Grass → Insects → Frog → Snake → Eagle.
11. How are food chains in the forest connected?
    Many food chains are linked to form a food web. If one chain is disturbed, it affects others. Example: If trees are cut, herbivores will not get food, so carnivores will also suffer.

Decomposers, Humus and Nutrient Cycle

12. What is humus? What is its importance?
    - Humus is a dark substance formed when dead plants and animals decay.
    - Importance: It adds nutrients to the soil and makes it fertile.
13. What are decomposers? Give examples.
    Decomposers are small organisms and microorganisms that break down dead plants and animals into humus.
    Examples: Mushrooms, bacteria, fungi, insects, millipedes, beetles, ants.
14. Why is the decaying matter on the forest floor warm?
    Because during decomposition, microorganisms release heat energy.
15. How are nutrients recycled in the forest?
    1. Dead plants and animals decay to form humus.
    2. Humus releases nutrients into the soil.
    3. These nutrients are absorbed by roots of living plants.
    4. This cycle goes on again and again.
    Thus, nothing goes waste in a forest.

Importance of Forests

16. Why are forests called a habitat?
    Because they provide food, water, shelter and protection to a large number of plants and animals.
17. How do forests help in rainfall?
    Forests release water vapour through transpiration, which helps in cloud formation and brings rainfall.
18. How do forests prevent soil erosion?
    Roots of trees hold the soil tightly. When trees are cut, soil is carried away by wind and water, causing erosion.
19. How do forests help in preventing floods?
    Forest soil and leaf litter absorb rainwater and allow it to seep slowly into the ground. This prevents flooding and maintains water table.
20. How do forests help in controlling pollution?
    1. They absorb carbon dioxide and noise.
    2. They release oxygen and keep the air clean.
    3. They keep the weather cool.

Consequences of Cutting Forests

21. What will happen if forests disappear?
    1. Carbon dioxide in air will increase → Earth's temperature will rise.
    2. Animals will not get food and shelter.
    3. Soil will not hold water → Floods will occur.
    4. Life and environment will be endangered.
22. How has human activity reduced forests?
    Roads, buildings, industries, overgrazing, and cutting trees for wood have reduced forests.

Preservation of Forests

23. What can we do to preserve forests?
    1. Plant more trees.
    2. Stop cutting trees unnecessarily.
    3. Control overgrazing.
    4. Use forest products wisely.
    5. Create awareness among people.
24. Summarise the importance of forests.
    1. Provide oxygen for breathing.
    2. Provide food, fodder, medicines, timber, and other products.
    3. Prevent soil erosion, floods, and natural disasters.
    4. Maintain water table and help in rainfall.
    5. Provide habitat for wildlife.
    6. Keep pollution under control.

Important Note: Forests are essential for maintaining ecological balance and supporting life on Earth. We must all contribute to forest conservation efforts.