Biomes (Cambridge (CIE) AS Environmental Management)

Revision Note

Author

Alistair Marjot

Expertise

Biology & Environmental Systems and Societies

Terrestrial Biomes

Biomes are large-scale ecological communities or ecosystem types that are characterised by their dominant vegetation, climate and other abiotic factors that shape their biotic communities
Biomes cover large geographic areas (different ecosystems can be found within a single biome):
- These larger zones have similar climatic and ecosystem characteristics
Terrestrial biomes (i.e. non-aquatic biomes) are classified into four major classes:
- Forest
- Grassland
- Desert
- Tundra
These major classes can be divided into further categories, for example:
- Forest biomes are dominated by trees and are categorised into tropical rainforests, temperate deciduous forests and boreal forests
- Grassland biomes are characterised by grasses and herbaceous plants and are categorised into savanna and temperate grasslands
- Desert biomes are characterised by low rainfall and are dominated by cacti and other drought-resistant plants - they can be further divided into subcategories such as hot deserts, cold deserts, coastal deserts and semi-arid deserts
- Tundra biomes are found in high latitudes and are characterised by low temperatures and permafrost - they can be further divided into subcategories such as arctic tundra and alpine tundra

Forest

Forest Biomes

Characteristics	Tropical rainforest	Temperate forest	Boreal forest
Location	Low latitudes Within Tropics: 23.5° north and south of equator E.g. Amazon in South America, New Guinea, Southeast Asia, Zaire Basin	Between 40°–60° north and south of equator E.g. Western Europe, northeast USA, Eastern Asia	Between 50°–60° north and south of equator E.g. Canada, Russia, Scandinavia
Annual precipitation	Over 2000 mm	750–1500 mm (all year round)	300–900 mm (all year round)
Temperature range	26 to 28°C	Over 0° C in winter 20 to 25°C in summer	-30°C in winter Up to 20°C in summer
Seasons	No seasons: hot and wet all year round	Four seasons of equal length	Two main seasons: winter and summer
Growing season	All year round	6–8 months	2–3 months
Soils	Relatively infertile due to leaching and rapid uptake of nutrients by plants	Relatively fertile and nutrient rich due to decomposition of organic matter over autumn and winter	Not very fertile: often acidic, with permafrost Shallow soil with a thick litter layer due to slow decomposition
Biodiversity	Approx. 50% of world's plant and animal species live within the rainforest biome Example flora: mahogany, teak trees, lianas, orchids Example fauna: Toucans, jaguars, frogs, snakes	Wide range of animals and plants with higher biodiversity than boreal forests Example flora: deciduous trees e.g. beech, oak, birch Example fauna: deer, rabbits, squirrels, bears	Less biodiverse than temperate forests Example flora: coniferous trees Example fauna: squirrels, bears, reindeer, wolves

Grassland

Grassland Biomes

Characteristics	Savanna	Temperate grasslands
Location	5°–30° north and south of equator North and south of tropical and monsoon forest biomes E.g. central Africa: Tanzania, Kenya	40°–60° north and south of equator E.g." veldts" of South Africa, "pampas" of Argentina, "steppes" of Russia, "plains" of USA
Annual precipitation	800–900 mm	250–750 mm
Temperature range	15–35°C	-40 to 40°C
Seasons	Wet and dry season	Four seasons
Growing season	During wet season (4–5 months)	During summer (dependent on temperature)
Soils	Free draining with thin layer of humus Not very fertile: most nutrients near surface	Fertile soil
Biodiversity	Wide range of plant and animal species Greatest diversity of hoofed animals Grasses, baobab and acacia trees Zebras, elephants, giraffes	Large numbers of plant and animal species Grasses, sunflowers Bison, antelopes, rabbits

Desert

Desert Biomes

Characteristics	Hot desert
Location	15°–30° north and south of equator North Africa e.g. Sahara, Southern Africa e.g. Kalahari and Namib, Australia, Middle East
Annual precipitation	Below 250 mm
Temperature range	Daytime temperatures can reach 50°C but average around 25°C Night time temperatures below 0°C
Seasons	Summer and winter
Growing season	All year round
Soils	Infertile, dry
Biodiversity	Low biodiversity Cacti, yucca Spiders, scorpions, camels, meerkats

Tundra

Tundra Biomes

Characteristics	Tundra
Location	North of the Arctic Circle and Antarctica
Annual precipitation	Less than 250 mm
Temperature range	Below 0°C for 6–10 months
Seasons	Winter and summer
Growing season	6–10 weeks
Soils	Thin infertile soil Permafrost
Biodiversity	Low biodiversity Small grasses, mosses, lichen Snowy owls, snow bunting, tundra swan Arctic foxes, hares and wolves Polar bears, musk ox and caribou

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