Forest: Our Lifeline CBSE Notes class 7th Science

Forests: Our Lifeline

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1. Forest

➥ A forest is a large area covered chiefly with trees and undergrowth, serving as a natural habitat for diverse species of plants and animals.

2. Canopy

➥ The uppermost branches and leaves of tall trees form a roof-like structure called the canopy.

3. Understoreys

➥ The layer of vegetation beneath the canopy is called the understorey, consisting of shrubs and small plants.

4. Dependence of Plants and Animals on Forests

1. Plants provide oxygen, food, and shelter for animals.
2. Animals help in pollination and seed dispersal.
3. Forests maintain ecological balance and biodiversity.

5. Food Chain

➥ A food chain shows how energy flows through an ecosystem, from producers to consumers.

1. Producers: Plants that make their own food through photosynthesis.
2. Consumers: Animals that depend on plants or other animals for food.
• Primary Consumers: Herbivores that eat plants.
• Secondary Consumers: Carnivores that eat herbivores.
• Tertiary Consumers: Top predators in the food chain.
3. Decomposers: Microorganisms that break down dead plants and animals into nutrients.

6. Food Web

➥ A food web consists of interconnected food chains, showing a more complex flow of energy in an ecosystem.

7. Natural Vegetation of India

1. Tropical Rainforests: Dense forests found in regions with heavy rainfall, containing evergreen trees.
2. Tropical Deciduous Forests: Also called monsoon forests; trees shed leaves in dry seasons.
3. Thorn Forests: Found in arid regions, consisting of thorny bushes and shrubs.
4. Tidal Forests: Mangrove forests found in coastal regions.
5. Coniferous Forests: Forests in mountainous regions, dominated by cone-bearing trees.

8. Importance of Forests

1. Forests are a vital resource providing timber, medicinal plants, and other products.
2. They maintain air humidity and rainfall by releasing water vapor.
3. Forests act as air purifiers by absorbing carbon dioxide.
4. They prevent soil erosion and maintain fertility.
5. Forests provide firewood, fodder, and livelihood for communities.

9. Deforestation

➥ Deforestation refers to the large-scale clearing of forests for agriculture, urbanization, or other activities.

10. Effects of Deforestation

1. Soil Erosion: Loss of fertile topsoil due to lack of vegetation cover.
2. Global Warming: Increased carbon dioxide levels causing temperature rise.
3. Floods: Lack of trees reduces water absorption, leading to flooding.
4. Droughts: Decreased rainfall due to deforestation.
5. Depletion of Water Table: Reduced water retention in soil.
6. Loss of Habitat: Wildlife loses shelter and food sources.

11. Conservation of Forests

1. Afforestation: Planting trees to restore forests.
2. Preventing Forest Fires: Taking measures to control accidental fires.
3. Stopping Mining in Forest Lands: Reducing exploitation of forested areas.
4. Preventing Overgrazing: Controlling the number of grazing animals.
5. Chipko Movement: A forest conservation movement in India that focused on preventing deforestation.

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