Class 8 Science Notes Chapter 7 (Conservation of Plants and Animals) – Science Book

We've made detailed notes for NCERT Class 8 Science Chapter 7: Conservation of Plants and Animals, tailored for government exam preparation.

Chapter 7: Conservation of Plants and Animals

Focus: Understanding the importance of biodiversity, the threats it faces (especially deforestation), and the methods employed for its conservation.

1. Deforestation and its Causes

• Definition: Deforestation is the clearing of forests on a large scale and using that land for other purposes.
• Causes:
  • Man-made:
    • Procuring land for cultivation (Agriculture).
    • Building houses, factories, and infrastructure (Urbanization & Industrialization).
    • Making furniture or using wood as fuel.
    • Overgrazing by animals.
  • Natural:
    • Forest fires.
    • Severe droughts.

2. Consequences of Deforestation

• Climate Change: Increases temperature and pollution levels on Earth. Increases the level of carbon dioxide (CO2) in the atmosphere, leading to global warming (as plants consume CO2 for photosynthesis).
• Lowering of Groundwater Level: Reduces water infiltration into the soil, disrupting the water cycle.
• Soil Erosion: Tree roots bind the soil. Removal of trees exposes the topsoil, which is easily removed by wind or water, leading to erosion.
• Desertification: Removal of fertile topsoil exposes lower, hard, rocky layers, reducing humus and fertility. Fertile land gradually gets converted into deserts.
• Loss of Biodiversity: Destroys habitats for countless plants and animals, leading to a decline in their populations and potential extinction.
• Disruption of Water Cycle: Reduces rainfall and affects the overall water balance.
• Decreased Water Holding Capacity of Soil: Leads to increased chances of floods.

3. Conservation of Forest and Wildlife

• Necessity: To protect our biodiversity, maintain ecological balance, preserve genetic diversity, and ensure the availability of resources for future generations.
• Methods: Establishing protected areas like Biosphere Reserves, Wildlife Sanctuaries, and National Parks. Implementing laws and policies (like the Forest Conservation Act). Promoting reforestation and sustainable practices.

4. Biodiversity

• Definition: Refers to the variety of living organisms existing on the Earth, their interrelationships, and their relationship with the environment. It includes diversity within species, between species, and of ecosystems.
• Flora: Refers to all the plant life found in a particular area. (Example: Sal, Teak, Mango, Jamun found in Pachmarhi Biosphere Reserve).
• Fauna: Refers to all the animal life found in a particular area. (Example: Chinkara, Blue-bull, Barking deer, Cheetal, Leopard, Wild dog, Wolf found in Pachmarhi Biosphere Reserve).

5. Endemic Species

• Definition: Species of plants and animals that are found exclusively in a particular geographical area and nowhere else naturally.
• Vulnerability: They are more vulnerable to extinction because habitat destruction, introduction of new species, or climate change in their specific area can wipe them out completely.
• Examples (from Pachmarhi Biosphere Reserve):
  • Flora: Sal, Wild Mango.
  • Fauna: Bison, Indian giant squirrel, Flying squirrel.

6. Species

• Definition: A group of populations whose members are capable of interbreeding naturally amongst themselves and producing fertile offspring. Members of a species share common characteristics.

7. Protected Areas

• Purpose: Areas designated for the protection and conservation of ecosystems and their constituent flora and fauna. Human activities like plantation, cultivation, grazing, felling trees, hunting, and poaching are prohibited or strictly regulated.
• Types:
  • Wildlife Sanctuary: Areas reserved for the protection of wild animals, providing suitable living conditions. Limited human activities (like grazing by livestock, collecting medicinal plants/firewood by forest dwellers) may be permitted, but activities that harm wildlife are prohibited. (Example: Bori Sanctuary in Madhya Pradesh).
  • National Park: Areas reserved for wildlife where they can freely use the habitats and natural resources. They are typically larger and provide a higher level of protection to the entire ecosystem (flora, fauna, landscape, historic objects). Human activities are highly restricted. (Example: Satpura National Park in Madhya Pradesh - India's first Reserve Forest).
  • Biosphere Reserve: Large areas of protected land meant for the conservation of wildlife, plant and animal resources, and the traditional life of the tribal people living in the area. They aim to conserve the biodiversity and culture of that area. A biosphere reserve may contain other protected areas within it (e.g., Pachmarhi Biosphere Reserve includes Satpura National Park and Bori & Pachmarhi Wildlife Sanctuaries).

8. Threatened Species

• Concept: Species whose populations have declined to levels where they face a high risk of extinction.
• Categories:
  • Endangered Species: Animals whose numbers are diminishing to a level that they might face extinction if the causal factors continue to operate. (Examples: Tiger, Snow Leopard, Great Indian Bustard, Lion-tailed Macaque).
  • Vulnerable Species: Species likely to become endangered unless the circumstances threatening their survival and reproduction improve.
  • Extinct Species: Species that no longer exist anywhere on Earth. (Examples: Dodo, Dinosaurs).

9. Ecosystem

• Definition: Consists of all the living organisms (plants, animals, microorganisms) in an area along with the non-living components such as climate, soil, river deltas, etc. All components are interdependent.

10. Red Data Book

• Definition: The source book which keeps an international record of all endangered animals and plants.
• Purpose: To provide information for monitoring the status of species and guiding conservation efforts.
• Maintained by: IUCN (International Union for Conservation of Nature) - This is an important fact for exams.
• Different books exist for plants, animals, and other species.

11. Migration

• Definition: The seasonal movement of a species (especially birds) from one habitat to another in search of favourable climate conditions, food, or for breeding purposes.
• Reason: To escape harsh, cold conditions or find suitable breeding grounds.
• Example: Siberian Cranes migrate thousands of kilometres from Siberia to places like Bharatpur in Rajasthan (India) during winter.

12. Recycling of Paper

• Importance: Paper is made from wood pulp (trees). Recycling paper saves trees, reduces energy and water consumption used in manufacturing paper, and decreases the use of harmful chemicals.
• Fact: It takes approximately 17 full-grown trees to make one tonne of paper.
• Benefit: Helps in conserving forests. Paper can be recycled 5-7 times.

13. Reforestation

• Definition: Restocking of destroyed forests by planting new trees.
• Methods:
  • Natural Reforestation: If the deforested area is left undisturbed, it can re-establish itself over time.
  • Planned Reforestation: Planting trees, preferably of the same species that were found in that forest.
• Recommendation: We should plant at least as many trees as we cut.
• Forest (Conservation) Act, India: Aims at preservation and conservation of natural forests and meeting the basic needs of the people living in or near the forests.

14. Project Tiger

• Objective: A wildlife conservation project launched by the Government of India in 1973 to protect the Bengal tiger in its natural habitats and ensure its survival.
• Significance: One of the most successful conservation ventures, aimed at maintaining a viable tiger population in India.

Key Takeaways for Exams:

• Definitions: Deforestation, Biodiversity, Flora, Fauna, Endemic Species, Species, Ecosystem, Migration, Reforestation.
• Distinctions: Wildlife Sanctuary vs. National Park vs. Biosphere Reserve (purpose, level of protection, examples).
• Causes and Consequences of Deforestation.
• Threatened Species Categories: Endangered, Extinct.
• Red Data Book: Purpose and maintaining body (IUCN).
• Examples: Pachmarhi Biosphere Reserve, Satpura National Park, Bori Sanctuary, Siberian Crane, Project Tiger.
• Importance of Paper Recycling and Reforestation.

These notes cover the essential concepts and facts from Chapter 7 relevant for government exam preparation, focusing on clarity, accuracy, and key information as per the NCERT Class 8 syllabus.