What is a biome?
The biosphere is the part of Earth where life exists: land, water and air together. A biome is a very large area of the biosphere with a similar climate and a similar set of plants and animals.
Two things mostly decide the biome: temperature and rainfall. Soil and height also matter.
Major land biomes of the world
| Biome | Climate | Plants and animals |
|---|---|---|
| Tropical rainforest | Hot and wet all year (> 200 cm rain) | Tall, dense evergreen trees in layers; monkeys, parrots. Most species of any biome. |
| Savanna | Hot, with a long dry season | Tall grass with scattered trees; zebras, lions, elephants. |
| Desert | Very dry (< 25 cm), hot days, cool nights | Cactus, thorny bushes; camels, lizards. |
| Temperate grassland | Warm summers, cold winters, moderate rain | Grass, few trees; bison, horses. Good farmland. |
| Taiga (coniferous forest) | Long cold winters, short summers | Pine, fir, spruce with needle leaves; moose, bears. |
| Tundra | Very cold, frozen ground, little rain | Mosses, lichens, small shrubs; reindeer, polar foxes. |
Water has biomes too: oceans, coral reefs, rivers, lakes and mangroves.
Biosphere reserves in India
A biosphere reserve is a large protected area that saves nature and supports the people living around it. India has 18 biosphere reserves; 12 of them are in UNESCO's world network. Examples: Nilgiri (the first, 1986), Sundarbans, Gulf of Mannar, Nanda Devi, Nokrek, Great Rann of Kutch, Panna, Cold Desert.
Each reserve has three zones:
- Core zone: fully protected; no human activity except monitoring.
- Buffer zone: around the core; research, education and limited use.
- Transition zone: outer part; villages, farming and eco-friendly work.
Forest dwellers and ecotourism
Forest dwellers are communities, many of them tribal, who live in or near forests and depend on them for food, fuel, medicine, fodder and income from minor forest produce like honey, tendu leaves, bamboo and mahua. Many follow traditions like sacred groves, where no tree is cut. The Forest Rights Act (2006) recognises their rights over land and produce they have used for generations.
Ecotourism is responsible travel to natural places that keeps the environment safe and benefits local people: local guides, homestays, limited visitors, no plastic. If done badly (too many tourists, hotels inside forests) it can harm the very nature it depends on.
Forest and wildlife conservation; forest fires
Why forests matter: they give oxygen, hold soil, store water, absorb CO₂, and are home to wildlife.
Threats: cutting for farms, mines and roads, hunting and poaching, invasive plants, and fires.
Ways to conserve:
- Protected areas: national parks (strict protection), wildlife sanctuaries, tiger and elephant reserves.
- Laws: Wild Life (Protection) Act 1972, Forest Conservation Act 1980.
- Projects: Project Tiger (1973), Project Elephant.
- People's action: Chipko movement (Uttarakhand, 1970s) where villagers hugged trees; the Bishnoi community protecting blackbucks and khejri trees; joint forest management.
Forest fires need three things: heat, fuel (dry leaves) and oxygen (wind). Most are started by people: careless campfires, burning fields, cigarettes. They destroy trees, animals and soil. Prevention: clear fire lines (strips with no fuel), watchtowers and satellite alerts, and never leave a fire burning.
Key formulas and definitions
- Biome is decided mainly by Temperature + Rainfall
- Cold → hot: Tundra, Taiga, Grassland, Desert, Savanna, Rainforest
- Biosphere reserve zones: Core (protected) → Buffer (research) → Transition (people)
- Fire triangle: Heat + Fuel + Oxygen; remove one and the fire stops
- India: 18 biosphere reserves (12 in UNESCO network)
Worked examples
1. A place gets 300 cm of rain a year and stays hot all year. Which biome?
Tropical rainforest.
2. Why do taiga trees have needle-shaped leaves?
Needles lose little water and let snow slide off, which helps in long cold winters.
3. A research station is allowed but no village. Which zone of a biosphere reserve is this?
The buffer zone (research is allowed; the core has no activity, the transition zone has villages).
4. How does a fire line stop a forest fire?
It removes the fuel. With nothing to burn, one side of the fire triangle is missing, so the fire stops there.
5. A forest of 500 km² loses 2% of its area each year. How much is lost in 3 years (simple, 2% of 500 each year)?
2% of 500 = 10 km² a year; 3 × 10 = 30 km².
Common mistakes
- Thinking a biome is one small forest. A biome is a very large region across many countries.
- Mixing up biosphere reserve zones. People live in the transition zone, not the core.
- Thinking forest dwellers always harm forests. Many protect them through traditions like sacred groves.
- Thinking forest fires are mostly natural. In India most are started by people.