Major Biomes of the World
The world's major biomes — rainforest, savanna, desert, Mediterranean, grassland, taiga, tundra — with climate, vegetation, soils and realms for UPSC.
SyllabusGS I · Salient features of world physical geography; distribution of key natural resources
Prerequisites: Soil Formation and the Soils of India · Pressure Belts, Winds and Jet Streams
The Hook: The Richest Forest on the Poorest Soil
In August 2019, fires across the Brazilian Amazon made headlines worldwide and set off a debate about deforestation, cattle ranching and the future of the world’s largest tropical rainforest. One of the facts that emerged in that debate surprises most people: land cleared from the rainforest often loses its fertility within a few years.
How can the most productive ecosystem on land stand on poor, leached soil? The answer — nutrients are held in the living forest, not in the ground — shows how climate, vegetation and soil work as one system. That system is a biome.
The Core Concept
A biome is a large natural community of plants and animals occupying a major region, shaped mainly by climate (temperature and rainfall) and recognised by its dominant vegetation. Biomes broadly follow the climatic belts set by latitude, pressure and winds, modified by altitude and distance from the sea.
The major terrestrial biomes
| Biome | Climate | Vegetation | Soil and fauna | Where |
|---|---|---|---|---|
| Tropical rainforest (equatorial) | Hot and wet all year; little seasonal change; daily convectional rain | Dense, evergreen, multi-layered (emergents, canopy, understorey); hardwoods such as mahogany, ebony, rosewood; lianas and epiphytes | Highest biodiversity on land; soils heavily leached and nutrient-poor — nutrients cycle rapidly through the biomass | Amazon basin, Congo basin, South-East Asia; in India, the Western Ghats and North-East |
| Tropical deciduous (monsoon) forest | Hot; seasonal rain with a long dry season | Trees shed leaves in the dry season — teak, sal, bamboo | Commercially valuable timber | India, Myanmar, Thailand, northern Australia |
| Tropical savanna | Hot; distinct wet summer and dry winter | Tall grasses with scattered trees (acacia, baobab); fire-adapted | Large herds of grazing animals and their predators | East Africa (Serengeti); Llanos (Orinoco basin, Venezuela–Colombia); Campos (Brazilian Highlands); northern Australia |
| Hot desert | Very low rainfall; extreme daily temperature range | Xerophytes — cacti, thorny scrub, deep or wide roots, fleshy stems, small or waxy leaves | Sparse; nocturnal, burrowing animals | Sahara, Arabian, Thar, Kalahari, Atacama, Australian deserts |
| Mediterranean | Hot, dry summers; mild, wet winters | Evergreen, drought-resistant shrubs and trees — maquis (Europe), chaparral (California); olives, cork oak | “Orchard lands”: citrus fruits, grapes, olives | Mediterranean basin, California, central Chile, south-western Cape, south-western Australia |
| Temperate grassland | Continental — hot summers, cold winters, moderate rainfall | Short grasses, few trees | Deep, fertile, humus-rich soils (chernozem); “granaries of the world” — wheat and livestock | Prairies, Pampas, Steppes, Veld, Downs (see table below) |
| Temperate deciduous forest | Four distinct seasons; rain throughout the year | Broad-leaved trees that shed leaves in autumn — oak, beech, maple | Fertile brown forest soils; much of it cleared for farming | Western and central Europe, eastern USA, eastern China, Japan |
| Taiga (boreal coniferous forest) | Long, severe winters; short, cool summers | Conifers — pine, spruce, fir, larch; needle-shaped leaves, conical shape to shed snow; softwood for pulp and paper | Acidic podzol soils; fur-bearing animals | Broad belt across northern North America and northern Eurasia (Canada, Scandinavia, Siberia) |
| Tundra | Very cold; short summer; permafrost | No trees — mosses, lichens, sedges, dwarf shrubs | Reindeer and caribou; Arctic fox; indigenous peoples such as the Inuit and Sami | North of the tree line in the Arctic; also high mountains (alpine tundra) |
Grasslands of the world — a favourite matching topic
| Grassland | Type | Region |
|---|---|---|
| Prairies | Temperate | North America (USA and Canada) |
| Pampas | Temperate | Argentina and Uruguay |
| Steppes | Temperate | Eurasia (Ukraine to Central Asia) |
| Veld (Velds) | Temperate | South Africa |
| Downs | Temperate | Australia (Murray–Darling basin) |
| Canterbury | Temperate | New Zealand (South Island) |
| Savanna | Tropical | Africa (largest extent) |
| Llanos | Tropical | Venezuela and Colombia (Orinoco basin) |
| Campos | Tropical | Brazilian Highlands |
Biogeographic realms
Alfred Russel Wallace divided the world’s land fauna into broad zoogeographic realms:
| Realm | Region |
|---|---|
| Palaearctic | Europe, northern Africa, Asia north of the Himalaya |
| Nearctic | North America (north of tropical Mexico) |
| Neotropical | Central and South America |
| Ethiopian (Afrotropical) | Africa south of the Sahara |
| Oriental (Indo-Malayan) | South and South-East Asia, including most of India |
| Australian | Australia, New Guinea and nearby islands |
Wallace’s Line runs between Bali and Lombok and between Borneo and Sulawesi, marking a sharp change from Asian (Oriental) to Australian fauna — deep water channels kept the two faunas apart even when sea levels were low.
India lies mostly in the Oriental realm, with Palaearctic elements in the Himalaya and Trans-Himalaya. The Wildlife Institute of India’s classification divides India into ten biogeographic zones: Trans-Himalaya, Himalaya, Desert, Semi-arid, Western Ghats, Deccan Peninsula, Gangetic Plain, North-East, Coasts and Islands.
graph TD
A[Climate: temperature and rainfall] --> B[Hot and wet all year: Tropical rainforest]
A --> C[Hot with dry season: Savanna or monsoon forest]
A --> D[Very dry: Desert]
A --> E[Dry summer, wet winter: Mediterranean]
A --> F[Continental, moderate rain: Temperate grassland]
A --> G[Cold, long winters: Taiga]
A --> H[Very cold, permafrost: Tundra]Why biomes matter for UPSC
- Climate change is shifting biome boundaries — tree lines are moving poleward and upslope, and permafrost thaw in the tundra releases carbon.
- Land-use change has converted large parts of temperate grasslands to farmland and is clearing tropical forests for agriculture and ranching.
- Biomes connect to Mains GS III topics: biodiversity, carbon sinks, and the livelihoods of forest and pastoral communities.
Memory Anchors
Temperate grasslands — “Please Pass Some Very Delicious Cake”: Prairies (N. America) · Pampas (Argentina) · Steppes (Eurasia) · Veld (South Africa) · Downs (Australia) · Canterbury (New Zealand).
Tropical grasslands — “Savanna, Llanos, Campos” = “SLC” — Africa, Venezuela, Brazil.
Mediterranean shrubs: Maquis is the Mediterranean’s; Chaparral is California’s.
Taiga vs tundra: Taiga has Trees (conifers); tundra has no trees (lichens, mosses).
Wallace’s Line: “Bali to Lombok — Break in Life.”
For Prelims
- Tropical rainforests have the highest biodiversity but nutrient-poor, leached soils; most nutrients are held in the vegetation.
- Llanos — Venezuela and Colombia; Campos — Brazil; Pampas — Argentina; Veld — South Africa; Downs — Australia; Steppes — Eurasia; Prairies — North America.
- Maquis and chaparral are Mediterranean shrub vegetation of Europe and California respectively.
- Taiga — coniferous softwoods, podzol soils; tundra — permafrost, mosses and lichens, no trees.
- Wallace’s Line separates Oriental and Australian faunas between Bali and Lombok.
- India has ten biogeographic zones (Wildlife Institute of India).
For Mains
- Dimensions: climatic controls on biomes; soil–vegetation relationships; human use (agriculture, timber, grazing); threats (deforestation, desertification, climate change, invasive species); conservation.
- Keywords: biome, ecotone, xerophyte, permafrost, nutrient cycling, carbon sink, tree line, biogeographic realm, endemism.
- Value-addition: the rapid loss of fertility on cleared rainforest land explains why shifting cultivation (jhum in India’s North-East) traditionally moved plots; temperate grasslands became the world’s wheat belts because of their deep, humus-rich soils.
Common Traps
Practice
Prelims
Match the grasslands with the regions where they are found:
| Grassland | Region |
|---|---|
| A. Pampas | 1. South Africa |
| B. Llanos | 2. Australia |
| C. Downs | 3. Argentina |
| D. Veld | 4. Venezuela and Colombia |
Select the correct answer using the code given below.
Solution
Pampas — Argentina (3); Llanos — Venezuela and Colombia (4); Downs — Australia (2); Veld — South Africa (1).
Answer: D
Consider the following statements:
- The taiga is dominated by coniferous trees that yield softwood.
- Permafrost and tall trees are characteristic of the tundra.
- Chaparral is the Mediterranean-type shrub vegetation of California.
Which of the statements given above is/are correct?
Solution
- Statement 1 — correct. Pine, spruce, fir and larch dominate the taiga; their softwood is used for pulp and paper.
- Statement 2 — wrong. The tundra has permafrost but no trees; vegetation is limited to mosses, lichens, sedges and dwarf shrubs.
- Statement 3 — correct. The European equivalent is maquis.
Answer: B
Wallace’s Line, which marks a sharp boundary between Asian and Australian fauna, passes between which of the following pairs of islands?
Solution
Wallace’s Line passes through the deep strait between Bali and Lombok and continues between Borneo and Sulawesi. Sumatra and Java both lie on the Asian side; Sri Lanka and Madagascar are unrelated to the line.
Answer: A
Mains
Explain why tropical rainforests, despite their luxuriant vegetation, have nutrient-poor soils. What are the implications for agriculture after deforestation?
Solution
Introduction: Tropical rainforests are the most productive and biodiverse land ecosystems, yet their soils are typically infertile. The explanation lies in climate and nutrient cycling.
Body:
- Leaching: heavy rainfall all year washes soluble nutrients and bases out of the soil; intense weathering leaves iron and aluminium oxides (laterisation).
- Rapid decomposition: high temperature and humidity break down leaf litter quickly, so little humus accumulates.
- Closed nutrient cycle: plant roots and fungi absorb released nutrients almost at once; most nutrients are stored in the living biomass, not the soil.
- After deforestation: the nutrient store is removed or burnt; rain leaches the remaining ash nutrients; yields fall within a few seasons; soils may harden; erosion increases; farmers move on to clear more forest.
- Indian link: traditional shifting cultivation (jhum) in the North-East relied on long fallow periods to let the forest restore fertility; shortening fallow cycles degrades land.
Conclusion: Rainforest fertility belongs to the forest, not the soil. Sustainable options — agroforestry, longer fallows, and protecting intact forest — work with this system rather than against it.
Quick Revision
| Point | One-liner |
|---|---|
| Biome | Large community shaped mainly by climate |
| Rainforest | Highest biodiversity; leached, poor soils |
| Savanna | Grass with scattered trees; wet–dry seasons |
| Mediterranean | Dry summer, wet winter; maquis, chaparral |
| Temperate grasslands | Prairies, Pampas, Steppes, Veld, Downs, Canterbury |
| Tropical grasslands | Savanna (Africa), Llanos, Campos |
| Taiga | Conifers, softwood, podzols |
| Tundra | Permafrost, mosses and lichens, no trees |
| Wallace’s Line | Between Bali and Lombok |
| India | Oriental realm; ten biogeographic zones |
Key Takeaways
- Biomes are climate written in vegetation: temperature and rainfall decide which plants dominate.
- Soil and vegetation co-evolve — fertile grassland soils became wheat belts; rainforest fertility lives in the trees.
- Grassland names and their continents are a reliable Prelims matching question; climate change and land-use change are the Mains angle.
Related Topics
- Soil Formation and the Soils of India
- Biogeography and Soils — quick revision
- Natural Vegetation and Wildlife
- Ecology and Ecosystems
- Climatology