Distribution and Characteristic of Biomes (Edexcel IGCSE Geography)

Distribution & characteristics of biomes

• There are 11 biomes in Earth's biosphere

• A biome is a group of ecosystems around the world with similar characteristics

Biome distribution

• Latitude: with distance from the equator temperatures and sunshine hours decrease 

• Precipitation: areas of high pressure experience low rainfall, and areas of low-pressure experience high rainfall

• Altitude: an increase in altitude leads to a decrease in temperature

• Continentality: locations further inland heat up more quickly in the summer and cool more quickly in the winter

• Ocean currents: warm and cold currents circulate in the oceans either warming or cooling the adjacent land 

Tropical biomes

Tropical rainforest characteristics

• Location

  • Low latitudes

  • Within the Tropics 23.5^° north and south of the equator

  • Amazon in South America, New Guinea, Southeast Asia, Zaire Basin

• Precipitation and temperature range

  • Over 2000mm of precipitation

  • Between 26-28^oC

• Seasons

  • No seasons - hot and wet all year round

  • Growing season - all year

• Soils

  • Infertile due to leaching and rapid uptake of nutrients by plants

• Biodiversity

  • About 50% of the world's plant and animal species live in the rainforest biome

  • Four layers of vegetation

    • Plants include mahogany, teak trees, lianas, orchids

  • Animals include toucans, jaguars, frogs and snakes

Temperate monsoon forest

• Location

  • Between 5° - 30^° north and south of the equator

  • Found in India, Central America, Southeast Asia

• Precipitation and temperature

  • Between 700-2000 mm of precipitation

  • Summer temperatures between 30-45^oC

  • Winter temperatures between 15-30^oC

• Seasons and growing season

  • Three seasons 

    • Cool, dry

    • Hot, dry

    • Rainy season

  • During the rainy season and cool, dry season

• Biodiversity

  • High levels of biodiversity

  • Range of plants including hardwood, deciduous trees, teak, mahogany, lianas and orchids

  • Animal species include monkeys, parrots, jaguars, panthers, snakes, frogs

Temperate & boreal forest biomes

Temperate forest

• Location

  • Between 40^°-60^° north and south of the equator

  • Main locations include Western Europe, North-east USA, Eastern Asia

• Precipitation and rainfall

  • Average precipitation between 750-1500 mm

  • Winter temperatures over 0^oC

  • Summer temperatures between 20^oC-25^oC

• Seasons and growing season

  • Four seasons of equal length - spring, summer, autumn and winter

  • A 6-8 month growing season

• Soils

  • Fertile soils

  • Nutrient-rich due to the decomposition of organic matter over autumn and winter

• Biodiversity

  • A wide range of animals and plants

  • Deciduous trees including beech, oak, birch

  • Animals include deer, rabbits, squirrels, bears

Boreal forest

• Location

  • Between 50^°-60^° north and south of the equator

  • Includes Canada, Russia, Scandinavia

• Precipitation and temperature

  • Between 300-900 mm of precipitation annually

  • Winter temperatures average -30^oC

  • Summer temperatures reach an average 20^oC

• Seasons and growing season

  • Two main seasons, winter and summer

  • A growing season of 2-3 months

• Soils

  • Not very fertile often acidic and contains permafrost

  • Shallow soil with a thick litter layer due to slow decomposition

• Biodiversity

  • Less biodiverse than temperate forests

  • Coniferous trees 

  • Animals include squirrels, bears, reindeer, wolves

Tropical & temperate grassland biomes

Tropical grasslands

• Location

  • North and south of the tropical and monsoon forest biomes 5^°-30^° north and south of the equator

  • Countries include Central Africa - Tanzania, Kenya

• Precipitation and temperature

  • Precipitation is between 800-900 mm

  • Temperatures range from 15^°C to 35^°C

• Seasons and growing seasons

  • The grasslands have a wet and dry season

  • The growing season is between 4-5 months (in the wet season)

• Soils

  • Free-draining soils with a thin layer of humus

  • Soils are not very fertile most nutrients near the surface

• Biodiversity

  • Wide range of plant and animal species 

  • Plants include grasses, baobab and acacia trees

  • Animals include zebras, elephants, giraffes

  • The greatest diversity of hoofed animals

Temperate grasslands

• Location

  • The Velds of South Africa, the Pampas of Argentina, and Steppes of Russia and the plains of the USA

  • Between 40^°-60^° north and south of the equator

• Precipitation and temperature

  • Between 250 - 750 mm

  • Temperatures vary between -40^°C to 40^°C

• Seasons and growing seasons

  • Four seasons

  • Growing season over the summer (dependent on temperature)

• Soils

  • Fertile soil

• Biodiversity

  • Large numbers of plant and animal species

  • Grasses, sunflowers

  • Bison, antelopes, rabbits

  • Grasses and trees

Desert biomes

• Location

  • Between 15^° - 30^° north and south of the equator

  • North Africa - Sahara, Southern Africa - Kalahari and Namib, Australia. Middle East

• Precipitation and temperature

  • Precipitation is below 250 mm annually

  • Daytime temperatures up to 50^°C but average around 25^°C

  • Night time temperatures below 0^°C

• Seasons and growing season

  • Two seasons summer and winter

  • Growing season is all year round

• Soils

  • Soils are infertile

• Biodiversity

  • Low diversity

  • Cacti, yucca

  • Spiders, scorpions, camels, meerkats

Tundra biomes

• Location

  • North of the Arctic Circle and Antarctica

• Precipitation and temperature

  • Less than 250 mm of precipitation

  • Temperatures are below 0^°C for 6-10 months 

• Seasons and growing season

  • Two seasons, winter and summer

  • Growing season of 6-10 weeks

• Soils

  • Thin infertile soil

  • Permafrost

• Biodiversity

  • Low biodiversity

  • Animal species include Arctic fox, polar bears, snowy owls. Arctic wolves, Arctic hares, caribou

  • Plant species include small grasses, mosses, lichen