Distribution and Characteristic of Biomes (Edexcel IGCSE Geography)

Distribution & Characteristics of Biomes

Spec point — 4GE1-S6.068

• 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

Map showing the distribution of the world biomes

Tropical Biomes

Spec point — 4GE1-S6.068

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 & Boreal Forest Biomes

Spec point — 4GE1-S6.068

Deciduous & coniferous forest biomes

Deciduous 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

Coniferous 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

Spec point — 4GE1-S6.068

Savanna & temperate grassland biomes

Savanna

• 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

Spec point — 4GE1-S6.068

Hot and cold desert biomes

Hot desert

• 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

Cold desert

• Location

  • Central Asia, Southeastern South America

• Precipitation and temperature

  • Precipitation is below 250 mm annually
  • Summer temperatures up to 10^°C
  • Winter temperatures can be as low as -40^°C

• Seasons and growing season

  • Two seasons summer and winter

• Soils

  • Soils are infertile

• Biodiversity

  • Low diversity
  • Shrubs and grasses
  • Camels, snakes, snow leopards

Tundra Biomes

Spec point — 4GE1-S6.068

Tundra and polar 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

Exam Hint You may be asked to describe and explain the distribution of biomes or climate patterns. Consider the following;

• Biome distribution

• Latitude

• Country and continent names

• Factors which affect the distribution - latitude, altitude, ocean currents, continentality

• Climate patterns

  • Temperature - maximum and minimum
  • Seasonal variations
  • Rainfall totals, maximum and minimum