Biodiversity and Conservation – Class 11 Geography Chapter 14 Notes & NCERT PDF

Class 11GeographyChapter 14NCERT book: Fundamentals of Physical Geography - Geography Class 11

Notes and a simple summary of Chapter 14 of the NCERT Class 11 Geography book, with the official chapter PDF, flashcards, an MCQ quiz and an AI tutor for your doubts.

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Chapter 14: Biodiversity and Conservation

Introduction

This chapter (Unit VI: Life on the Earth) explains biodiversity and why its conservation matters. The weathering mantle, shaped by solar energy and water, is the basis for the diversity of vegetation and hence biodiversity — areas rich in these inputs have a wide range of biodiversity.

Today's biodiversity is the result of 2.5–3.5 billion years of evolution. Before humans, the earth supported more biodiversity than at any other time; since humans emerged, it has declined rapidly, with species going extinct due to overuse.

Estimates of the number of species range from 2 million to 100 million, with 10 million as the best estimate. New species are found regularly; about 40 per cent of South American freshwater fishes are not yet classified.

Tropical forests are very rich in biodiversity.

The average half-life of a species is 1–4 million years, and 99 per cent of species that ever lived are now extinct.

Biodiversity is richer in the tropics; towards the poles there are larger populations of fewer species.

Key Concepts

1. What is Biodiversity?

Bio (life) + diversity (variety) = the number and variety of organisms in a specified region. It includes plants, animals, micro-organisms, their genes and the ecosystems they form — variability within and between species and ecosystems. Biodiversity is our living wealth.

2. Levels of Biodiversity

Genetic diversity — variation of genes within a species. Humans all belong to Homo sapiens but differ in height, colour and appearance because of genetic diversity. It is essential for healthy breeding of a species.

Species diversity — the variety of species in an area, measured by richness, abundance and types. Areas rich in species are hotspots.

Ecosystem diversity — differences between ecosystem types and the diversity of habitats and ecological processes within them. Ecosystem boundaries are not rigid, so demarcation is difficult. (Example: grasslands and sholas in Indira Gandhi National Park, Annamalai, Western Ghats.)

3. Importance of Biodiversity

Biodiversity has shaped human culture, and humans have shaped biodiversity. It plays three roles:

Ecological role — every organism takes what it needs and also contributes to others. Species capture and store energy, produce and decompose organic matter, cycle water and nutrients, fix atmospheric gases and regulate climate. The more diverse an ecosystem, the more stable and productive it is, and the better it adapts to change.

Economic role — biodiversity supplies food crops, livestock, forests, fish and medicinal resources. Crop diversity is called agro-biodiversity. Treating biodiversity as a reservoir of resources for food, pharmaceuticals and cosmetics has led to its deterioration and to conflicts over resources.

Scientific role — each species gives clues about how life evolved and functions, and the role of each species in ecosystems.

Ethical view — every species has an intrinsic right to exist; it is morally wrong to cause extinction. The level of biodiversity indicates the health of our relationship with other species.

4. Loss of Biodiversity

A growing human population has increased consumption of natural resources.

Tropical regions cover only about one-fourth of the world's area but hold about three-fourths of the human population. Over-exploitation and deforestation are rampant there.

Tropical rain forests contain 50 per cent of the species on earth, so their destruction harms the whole biosphere.

Natural calamities — earthquakes, floods, volcanic eruptions, forest fires, droughts.

Pesticides and pollutants — hydrocarbons and toxic heavy metals destroy weak and sensitive species.

Exotic species — species introduced into a habitat where they are not natural; they have often damaged local biotic communities.

Poaching — tigers, elephants, rhinoceros, crocodiles, minks and birds hunted for horns, tusks and hides, making some endangered.

5. IUCN Categories of Threatened Species

The International Union for Conservation of Nature and Natural Resources (IUCN) classifies threatened species into three categories:

Endangered — in danger of extinction. The IUCN publishes the Red List of threatened species. (Example in the book: Red Panda.)

Vulnerable — likely to become endangered in the near future if threats continue; survival not assured as populations have fallen greatly.

Rare — very small world populations, confined to limited areas or thinly scattered. (Example: Humboldtia decurrens, a highly rare endemic tree of the southern Western Ghats.)

6. Conservation of Biodiversity

All life forms are interlinked; disturbing one causes imbalance in others and may threaten human existence itself.

People need to adopt environment-friendly practices so development is sustainable. Conservation with sustainable use needs the involvement of local communities and local institutions. The key is to continue the process of conservation.

India and 155 other nations signed the Convention on Biodiversity at the Earth Summit, Rio de Janeiro, Brazil, June 1992.

World Conservation Strategy — suggested steps

(i) Preserve endangered species.

(ii) Plan and manage to prevent extinction.

(iii) Preserve varieties of food crops, forage plants, timber trees, livestock and their wild relatives.

(iv) Each country should identify and protect habitats of wild relatives.

(v) Safeguard habitats where species feed, breed, rest and nurse their young.

(vi) Regulate international trade in wild plants and animals.

India's measures — the Wild Life (Protection) Act, 1972, under which national parks and sanctuaries were established and biosphere reserves declared.

Mega diversity centres — tropical countries holding a large share of the world's species: 12 countries — Mexico, Colombia, Ecuador, Peru, Brazil, Democratic Republic of Congo, Madagascar, China, India, Malaysia, Indonesia and Australia.

Biodiversity hotspots

The IUCN has identified hotspots to focus resources on the most vulnerable areas.

Hotspots are defined by their vegetation, because plants determine the primary productivity of an ecosystem.

Most hotspots rely on species-rich ecosystems for food, firewood, cropland and timber income.

In Madagascar, about 85 per cent of plants and animals are found nowhere else. In wealthy regions like Hawaii, unique species are threatened by introduced species and land development.

Diagrams to Know

Three levels of biodiversity — genetic within species → species within an area → ecosystems within a landscape.

A world map of ecological hotspots, including the Western Ghats and Eastern Himalayas regions.

Key-Facts Sheet

Species estimates: 2–100 million; best estimate 10 million.

Evolution: 2.5–3.5 billion years; 99% of species ever lived are extinct.

Tropics: ¼ of area, ¾ of population; rain forests hold 50% of species.

IUCN categories: endangered, vulnerable, rare; the Red List.

Earth Summit: Rio de Janeiro, June 1992; Wild Life (Protection) Act: 1972.

12 mega diversity countries, including India.

Exam Focus

MCQ from the exercise: conservation matters for all organisms; threatened species are those in danger of extinction; national parks are for conservation; biodiversity is richer in tropical regions; the Earth Summit was held in Brazil.

30-word: What are hotspots? Outline: areas rich in species diversity, defined by vegetation, which IUCN targets for conservation.

What are exotic species? Outline: species introduced into a habitat where they are not natural inhabitants, often harming local communities.

150-word: Causes of biodiversity loss and steps to prevent it. Outline: population pressure, deforestation, calamities, pollution, exotic species, poaching → World Conservation Strategy steps, Wild Life Act 1972, community involvement.

Key Terms

Biodiversity (जैव विविधता)

Genetic diversity (आनुवंशिक विविधता)

Species diversity (प्रजातीय विविधता)

Ecosystem diversity (पारितंत्र विविधता)

Agro-biodiversity (कृषि जैव विविधता)

Hotspot (तप्त स्थल / हॉटस्पॉट)

Endemic (स्थानिक)

Endangered species (संकटापन्न प्रजाति)

Vulnerable species (सुभेद्य प्रजाति)

Rare species (दुर्लभ प्रजाति)

Exotic species (विदेशी प्रजाति)

Mega diversity centre (वृहत् विविधता केंद्र)

Biosphere reserve (जीवमंडल निचय)

Conservation (संरक्षण)

Common Mistakes

Confusing genetic diversity (within a species) with species diversity (number of species).

Mixing up vulnerable (may become endangered) with endangered (already in danger of extinction).

Thinking biodiversity is richest near the poles — it is richest in the tropics.

Forgetting that hotspots are defined by vegetation.

Writing the wrong year or place for the Earth Summit — it was Rio de Janeiro, June 1992.

💡 Key Learning Points

✓Biodiversity is the number and variety of organisms, their genes and ecosystems in a region.
✓It exists at three levels: genetic, species and ecosystem diversity.
✓Biodiversity plays ecological, economic and scientific roles, and every species has an intrinsic right to exist.
✓Population pressure, deforestation, calamities, pollution, exotic species and poaching cause biodiversity loss.
✓Conservation includes IUCN categories, the World Conservation Strategy, the Wild Life (Protection) Act 1972 and hotspots.

👨‍🏫 Teaching Tips

→Start with a schoolyard survey: list the plants, insects and birds students can find in 15 minutes.
→Use the example of human variety to explain genetic diversity.
→Show a world map of hotspots and locate the Western Ghats and the 12 mega diversity countries.
→Assign groups to research one endangered Indian species from the IUCN Red List.
→Hold a debate on development vs conservation using a local forest or wetland example.
→Do the project work: map national parks, sanctuaries and biosphere reserves in your state.
→Discuss an exotic species problem, such as invasive weeds in Indian lakes.

📋 Assessment Questions

Define biodiversity and explain its three levels.
Describe the ecological, economic and scientific roles of biodiversity.
What are the major causes of biodiversity loss?
Explain the IUCN categories of threatened species.
What steps did the World Conservation Strategy suggest for conserving biodiversity?

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