Global Biomes

What Global Biomes covers

Global biomes is examined in Unit AS 1, Physical Geography. It covers the global distribution of biomes, the tundra biome: climate and soils, the temperate grassland biome: climate and soils and climate change and tundra ecosystems.

The 4 subtopics

Each one has its own page.

• The global distribution of biomesWhat a biome is, where the tropical rainforest, hot desert, temperate grassland and tundra each lie, and why the real pattern does not follow neat latitudinal bands.Open →
• The tundra biome: climate and soilsTemperature regime of the tundra, active layer and characteristics of a typical tundra soil.Open →
• The temperate grassland biome: climate and soilsClimate of the temperate grassland biome and process of calcification in a temperate grassland soil.Open →
• Climate change and tundra ecosystemsAlready happening to permafrost as the climate warms and permafrost carbon feedback.Open →

What you need to know

Answer each one before you reveal it.

Take Global Biomes further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Biome vs Ecosystem

  Biome: a global-scale plant and animal community defined by climate. Ecosystem: a community of organisms and the physical setting it interacts with, at any scale.

• Tundra vs Temperate grassland

  Tundra: a cold zone of low shrubs, mosses and lichens over permafrost. Temperate grassland: a mid-latitude zone of deep-rooted grasses on fertile soils.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What is a biome?

   Model answer

   A biome is a very large-scale ecosystem, covering a large part of a continent, in which a distinctive community of plants and animals has developed in response to the climate of that zone. Its vegetation has a characteristic structure and the species within it share adaptations to the same conditions of temperature, moisture and light. Because climate is arranged in broad latitudinal belts, biomes are too, though relief, ocean currents and distance from the sea modify the pattern.

2. 2

   Where in the world is the tropical rainforest biome found?

   Model answer

   In a discontinuous belt straddling the Equator, mostly within about ten degrees north and south of it and extending in places to the tropics. The three great blocks are the Amazon basin of South America, the Congo basin of central Africa, and South East Asia and the islands of Indonesia, Malaysia and New Guinea. Smaller areas occur in Central America, the eastern coast of Madagascar, west Africa and north-east Australia. The distribution follows the zone where the Intertropical Convergence Zone brings high temperatures and heavy convectional rainfall throughout the year.

3. 3

   Where are the hot desert biomes found, and why are they where they are?

   Model answer

   They are centred on latitudes of about twenty to thirty degrees north and south, along and just outside the tropics, and they are typically on the western sides of continents and in continental interiors. The main examples are the Sahara and Arabian deserts, the Kalahari and Namib in southern Africa, the Atacama in South America, the Australian deserts, and the Mojave and Sonoran deserts of North America. They occur there because the descending limb of the Hadley cell creates a belt of subtropical high pressure, in which sinking air warms and dries and cloud cannot form. This is reinforced by great distance from the sea in continental interiors, by rain shadows behind mountain ranges, and by cold offshore currents that chill and stabilise the air along coasts such as the Atacama and the Namib.

4. 4

   Where is the temperate grassland biome found?

   Model answer

   In the continental interiors of the mid-latitudes, broadly between about thirty and fifty-five degrees north and south. The main areas are the Prairies of the United States and Canada, the Steppes stretching from Ukraine across southern Russia into central Asia, the Pampas of Argentina and Uruguay, the Veld of South Africa, and the Canterbury Plains of New Zealand. They lie too far from the ocean, and often in the rain shadow of mountain ranges, for enough rainfall to support forest, but they receive enough for a continuous cover of grasses.

5. 5

   Where is the tundra biome found?

   Model answer

   In the high latitudes of the northern hemisphere, generally north of about sixty to sixty-six degrees, forming a belt between the northern edge of the coniferous forest, or taiga, and the permanent ice of the Arctic. It covers northern Alaska, the northern mainland and islands of Canada, the ice-free coastal fringe of Greenland, northern Scandinavia, Iceland and a vast area of northern Siberia. It is overwhelmingly a northern hemisphere biome because at the equivalent southern latitudes there is almost no land, only the Southern Ocean; small equivalent areas occur on the Antarctic Peninsula and on sub-Antarctic islands. Alpine tundra also occurs above the treeline on high mountains in lower latitudes.

6. 6

   Why does the vegetation of a biome change as you move from the Equator to the poles?

   Model answer

   Because the two factors that limit plant growth, warmth and moisture, change systematically with latitude. Insolation is intense and year-round at the Equator and becomes progressively weaker and more seasonal towards the poles, so the length of the growing season shortens from twelve months to less than three. Rainfall varies with the general circulation of the atmosphere, being heavy where air rises at the Equator, minimal where it sinks at the tropics, and moderate in the mid-latitude belt of depressions. As warmth and water become scarcer, vegetation becomes shorter, simpler in structure, less diverse and less productive, so tall, multi-layered, evergreen rainforest gives way through desert scrub, grassland and coniferous forest to low, ground-hugging tundra.

What is inside Levo

Six ways to work the same material.

Global Biomes revision questions

What does Global Biomes cover in CCEA A-Level Geography?

4 subtopics: the global distribution of biomes, the tundra biome: climate and soils, the temperate grassland biome: climate and soils and climate change and tundra ecosystems. Each one has its own page with questions and model answers.

How is Global Biomes organised?

By the CCEA 3910 specification, subtopic by subtopic, so it matches the order you are taught it in.