NCERT Revision Notes · Class 9 Social Science
Life on Earth
Understanding Society: India and Beyond — Class 9, Part 2
How climate and landforms decide what life grows where (biomes), how humans and nature depend on each other, and why and how we must conserve forests, wildlife and shared natural resources.
1. What is a Biome?
Biome = a large natural region of the world where certain types of plants and animals live under similar climatic conditions.
Word origin: bio (Greek bios = life) + -ome (a suffix meaning a group of biological constituents).
A biome is a broad environmental region. An ecosystem is like a neighbourhood inside it, where plants, animals and non-living things interact closely.
Think of the Earth as a giant patchwork quilt — each patch has its own colours, weather and living beings.
Factors that decide a biome: temperature, precipitation (rainfall) patterns, dominant plant species, growth forms of vegetation.
2. Types of Biomes
A. Terrestrial (land-based)
| Biome | Climate | Plants | Animals / Examples |
|---|---|---|---|
| Forest (Tropical rainforest) | Hot & wet all year; near the Equator, 23.5°N – 23.5°S | Dense, layered forest | Amazon Basin, Congo Basin, SE Asia; in India — Andaman & Nicobar, North-East |
| Grassland | Moderate rainfall — not enough for dense forest | Mainly grass, very few trees | Temperate: prairies (N. America), steppes (Asia) — fertile, used for farming. Tropical (Savanna): Africa — lions, elephants, giraffes |
| Desert | Driest biome, very little rain. Hot (Sahara) or cold (Gobi) | Cacti, sparse vegetation, sandy soil | Camels, lizards, snakes; Rann of Kutch — one of the world's largest salt deserts |
| Tundra | Coldest; near Arctic & Antarctic. Long harsh winters, short summers. Soil frozen all year = permafrost | Only mosses, lichens, small shrubs (no trees) | Reindeer, arctic fox, polar bear. Very fragile — small temperature change upsets it |
- Temperate deciduous biome — broad-leaved trees that shed leaves seasonally; moderate temperature, distinct seasons.
- Taiga biome — coniferous forests of pines, spruces and larches.
Layers of a rainforest (top to bottom)
Emergent layer Upper canopy Understory / lower canopy Forest floor. Sunlight decreases as you go down.
Rainforests are the richest storehouse of biodiversity and are called a 'gene bank' because they preserve unique genetic material.
B. Aquatic (water-based)
- Cover about three-fourths of the Earth's surface.
- Freshwater — rivers, lakes, ponds, wetlands. Needed for drinking water and agriculture; home to fish, frogs, insects.
- Marine — oceans, seas, coral reefs. Rich in biodiversity; store and distribute heat, so they influence the Earth's climate.
Biome pyramid
Biome pyramid = a graphical representation showing the relationship between organisms in a biome in terms of energy, number or biomass.
- Base = producers (plants and algae) — they capture solar energy by photosynthesis.
- Then herbivores (primary consumers) carnivores (secondary) top predators (tertiary).
- As we move up, number of organisms, biomass and available energy all decrease — because energy is lost as heat at each trophic level.
3. Biodiversity & Its Conservation
Biodiversity = the variety of life on Earth — plants, animals, microorganisms and the ecosystems they live in. It includes the number of species, the genetic differences within a species, and the variety of habitats and ecological processes.
Five geographical aspects of conservation
- Hotspots of biodiversity — regions rich in unique species found nowhere else. In India: the Himalaya, the Western Ghats, North-East India, Andaman & Nicobar Islands.
- Ecosystem-based conservation — the strategy must suit the setting, e.g. mangrove protection on coasts, afforestation in mountains.
- Protected areas — national parks, wildlife sanctuaries, biosphere reserves, World Heritage Sites; chosen by geography to preserve habitats and prevent habitat fragmentation.
- Geographical barriers & corridors — rivers, mountains and valleys control animal movement and gene flow; used to plan wildlife corridors.
- Human–environment interaction — sustainable practices vary with geography, e.g. terrace farming in hills, agroforestry in plains.
- Namdapha National Park — Arunachal Pradesh (four big cats)
- Rann of Kutch — Gujarat (salt desert, wild ass, flamingos)
- Gahirmatha beach — Odisha (Olive Ridley turtles)
- Gulf of Mannar — Tamil Nadu (coral reefs, dugong)
- Pachmarhi — Madhya Pradesh (Satpura, biosphere reserve)
- Achanakmar–Amarkantak — Chhattisgarh / MP (source of Narmada & Son)
4. Forests, People & Livelihoods
Ecotourism
Ecotourism = travelling to nature-friendly places without harming the environment and while supporting local people.
- Unlike mass tourism it stresses minimal environmental impact, respect for local communities and learning about ecosystems.
- Thenmala, Kollam district, Keralam — India's first planned ecotourism destination. Name means 'Honey Hill'. In the Western Ghats, a UNESCO World Heritage Site. Locals employed as guides and eco-guards.
- Swadesh Darshan 2.0 Scheme (Ministry of Tourism) — develops sustainable tourism destinations with community involvement.
Forest dwellers — their connection with forests
| Role | What they do |
|---|---|
| Knowledge holders | Traditional knowledge of herbs, plants and forest resources, passed down generations helps biodiversity conservation |
| Livelihood & income | Gather and process non-timber forest products (NTFPs) — tendu leaves, mahua flowers, honey, lac, bamboo |
| Household needs | Firewood, fodder, wild fruits, roots, tubers, medicinal plants |
| Forest protection | Led movements — Bishnoi Movement (Rajasthan, Amrita Devi) which influenced the Chipko Movement (Uttarakhand, women hugged trees) |
| Cultural & social | Forests linked to rituals, festivals and beliefs — they are guardians of ecological and cultural traditions |
Women play a vital role in collecting and managing forest resources and in keeping traditional knowledge alive. Communities such as the Gonds and Bhils perform rituals to honour forest deities before collecting resources.
Sacred groves
- Small forest patches protected by local communities for religious and cultural reasons.
- India has over 1,00,000 sacred groves, many unrecorded.
- Local names: Devrai, Devarakadu, Kavu, Sarna.
- Though small, they are rich biodiversity hotspots and often protect water sources.
Geographical Indication (GI) tag
GI tag = an intellectual property right identifying a product as originating from a specific place, where its quality or reputation is essentially linked to that geographic origin.
| GI product | State | Known for |
|---|---|---|
| Ramban Sulai Honey | Jammu & Kashmir | Antioxidant, distinct flavour |
| Tezpur Litchi | Assam | Bright colour, high pulp |
| Channapatna Toys | Karnataka | Made from Wrightia tinctoria, locally 'Aale mara' |
| Kandhamal Haldi | Odisha | High curcumin, grown by tribal communities |
| Erode Manjal (turmeric) | Tamil Nadu | Cooking & ayurvedic medicine |
| Nilgiri Tea | TN / Keralam / Karnataka | Depends on Western Ghats ecosystem |
| Tripura Queen Pineapple | Tripura | Sweetness and aroma |
| Khasi Mandarin | Meghalaya | Citrus from forest-rich hills |
5. Challenges Faced by Forest Communities
- Poor access to healthcare, education and clean water.
- Women exposed to fuelwood fumes health problems. (PMUY — Pradhan Mantri Ujjwala Yojana gives LPG connections to reduce this.)
- Conflict between conservation laws and survival — restrictions on forest use, deforestation and commercial exploitation limit their access.
- Natural disasters — floods, landslides, forest fires.
- Human–wildlife conflict — crops damaged by elephants, monkeys, wild boars; sometimes direct attacks.
- Discrimination and neglect; forest produce sold at low prices need for processing and marketing facilities.
Forest fires. As per the Forest Survey of India (FSI), about 36% of India's forest cover is prone to forest fires, of which nearly 4% is extremely prone. Causes: climate change + human-induced factors.
Fire needs three things together — fuel, heat and oxygen. Prevention works by removing any one: fire lines and controlled burning (remove fuel), ban on open flames (remove heat), water and sand (cut off oxygen).
6. Government Efforts for Forest Dwellers
- FRA, 2006 — Scheduled Tribes and Other Traditional Forest Dwellers (Recognition of Forest Rights) Act. Recognises rights over forest land and resources; allows collection of minor forest produce; grants ownership of small cultivated plots.
- JFM — Joint Forest Management: local communities help protect forests and share the produce.
- PESA — Panchayats (Extension to Scheduled Areas) Act.
- DAJGUA — Dharti Aaba Janjatiya Gram Utkarsh Abhiyan.
- PM JANMAN — Pradhan Mantri Janjati Adivasi Nyaya Maha Abhiyan.
Case study — Mendha Lekha
- Small tribal village in Gadchiroli district, Maharashtra; inhabited mainly by the Gond tribe.
- First village in India to gain rights over its forest resources under the FRA (2006).
- Follows the principle Mawa Nate Mawa Raj — "our village, our rule". All decisions taken collectively through the Gram Sabha.
- Protects and sustainably uses 1,800 hectares of forest — regulates tree cutting, prevents forest fires, promotes bamboo as a renewable resource.
- Revenue from forest produce is spent on community welfare — education and infrastructure.
- Shows that traditional knowledge + rights + duties + democratic participation can achieve sustainable conservation.
7. Ecological Commons
Ecological commons = natural resources such as forests, rivers, lakes, grazing lands, air and biodiversity that are shared by a community and used collectively. They are not owned by any single individual and are managed through traditional rules.
Threats: population growth, industrial use and privatisation are shrinking and degrading the commons.
Two case studies
- Fisheries in Bihar — historically, large landowners controlled water bodies and diara waterfronts, marginalising fishing communities. The Bihar Fish Jalkar Management Act, 2006 introduced a commons-based management model with community-led management and public access. Result: steady growth in fish production.
- Water tanks built by the Gond kings — between 800 and 1200 CE the Chandella and Bundela kings built around 8,000 tanks in Bundelkhand. Others: keres (Karnataka), eri tanks (Tamil Nadu), chevuru tanks (Andhra Pradesh & Odisha), ahar pynes (Bihar), and huge three-sided katas funded by the Gond kings in Gondwana. India has more than 15 lakh functional tanks today.
Quick Revision
Life on Earth · Revision notes for Class 9 Social Science.
Based on the NCERT textbook Understanding Society: India and Beyond — Class 9, Part 2. Figures taken from the same chapter for study purposes.