Biomes
Large climate regions of the Earth, land and water, and the threats they share
Scope: Biomes as large climate-defined regions. The whole zone of life is covered in the note on the biosphere.
In one minute
A biome is a large region of the Earth with a distinct climate and the plants and animals suited to it. Examples are a desert, a tropical rainforest and a tundra.
Biomes are either on land or in water. Exams ask for the kinds of biome, one example of each, and the threats they face.
Exam focus
- Frequency: Rarely asked
- Usually asked as: Short answer (4 to 6 marks)
Legal provision
No Indian Act defines a biome. The concept matters because many protections are designed around regions of distinct life.
- Section 2(b), Biological Diversity Act, 2002: biological diversity includes diversity "of eco-systems", which covers the variety found across biomes.
- Conservation tools: sanctuaries, national parks and biosphere reserves are used to protect samples of different biomes.
Meaning and definition
A biome is a large geographical region marked by a distinct climate and by the plant and animal communities adapted to it. An ecosystem can be as small as a pond. A biome spreads across a continent.
- Biomes
- Terrestrial (land)Tropical rainforest, savanna, desert, temperate grassland, temperate forest, taiga, tundra.
- Aquatic (water)Freshwater, marine, estuaries.
Detailed explanation
Step 1: the main biomes
| Biome | Climate | Typical life | Example |
|---|---|---|---|
| Tropical rainforest | Warm, humid, heavy rain | Dense evergreen trees, parrots, insects | Amazon Basin |
| Savanna | Hot, seasonal rain | Grasses, acacia, lions, elephants | African savanna |
| Desert | Very little rain | Cacti, shrubs, reptiles | Thar Desert |
| Temperate grassland | Moderate rain, hot summers, cold winters | Grasses, bison | North American prairies |
| Temperate forest | Moderate, with four seasons | Deciduous trees, deer | Eastern United States |
| Taiga | Long cold winters, mild summers | Conifers, moose, wolves | Siberian taiga |
| Tundra | Extremely cold, little precipitation | Mosses, lichens, Arctic fox | Arctic tundra |
| Freshwater | Non-saline water | Algae, fish, amphibians | Ganga river system |
| Marine | Salt water | Coral, plankton, whales | Coral reef systems |
| Estuary | Fresh and salt water mix | Mangroves, crabs, migratory birds | Sundarbans |
Step 2: why biomes matter
Biomes hold biodiversity, help control climate and supply timber, food and medicine. They also provide services such as pollination and the recycling of nutrients. This is why law and treaties aim to protect samples of each kind.
Step 3: threats
The threats are much the same across biomes: deforestation, climate change, pollution, overuse and loss of habitat. The harm shows in different ways. A desert may spread, a forest may shrink, and an estuary may change in salinity.
Example. Rising sea level and cyclones threaten the mangroves of the Sundarbans estuary. Cutting and pollution compound the damage. A treaty or a court order aimed at that estuary protects one whole biome.
Don't confuse: biome and ecosystem
| Point | Biome | Ecosystem |
|---|---|---|
| Size | Continental or regional | Any size, down to a pond |
| Defined by | Climate and typical plants and animals | Living and non-living things interacting |
Inside the concept. The Thar Desert, with its low rainfall and drought-hardy shrubs, is a biome.
Just outside it. One oasis in that desert, with its pool, palms and insects, is an ecosystem within the biome.
Common mistakes
- Calling a single pond a biome. A pond is an ecosystem.
- Listing only land biomes. Freshwater, marine and estuary biomes are also biomes.
- Treating the biosphere as one more biome. The biosphere contains all biomes.
Leading case laws
No Indian case turns on the meaning of biome. Protection of particular biomes appears in cases on forests, coasts and wetlands, covered in the notes on those topics.
How to write this answer in the exam
5-mark answer
- Definition of biome.
- Terrestrial and aquatic types.
- Two or three examples with climate.
- Common threats.
10-mark answer
- Definition and scale.
- Classification: terrestrial and aquatic.
- Table of the main biomes with climate, life and example.
- Importance of biomes.
- Threats and conservation tools.
- Difference from ecosystem and biosphere.
Key points to remember
- Biome: large region defined by climate and its adapted life.
- Terrestrial: rainforest, savanna, desert, grassland, temperate forest, taiga, tundra.
- Aquatic: freshwater, marine, estuary.
- Threats: deforestation, climate change, pollution, overuse, habitat loss.
- Biomes are larger than ecosystems and smaller than the biosphere.
Quick self-test
1. Name the two broad groups of biome.
Terrestrial (land) and aquatic (water).
2. Is the Thar Desert a biome or an ecosystem?
A biome. A single oasis within it would be an ecosystem.
3. Name two threats common to most biomes.
Any two of deforestation, climate change, pollution, overuse and habitat loss.