Biome Distribution & Characteristics (Edexcel GCSE Geography B)
Revision Note
Written by: Bridgette Barrett
Reviewed by: Jenna Quinn
Impact of Climate on Biome Distribution
There are 9 biomes in Earth's biosphere
Biome distribution
The main factor affecting biome distribution is climate
Each biome has its own distinct characteristics which are determined by its climate, this affects:
Length of the growing season
Temperature and precipitation levels, which in turn, impact on the amount of plant growth
This impacts on each biome's biodiversity
The hotter and wetter a place is, the more plant species there tends to be
These provide food and habitats for animals; so the greater the number of animal species
Worked Example
Define the term biodiversity
(1 mark)
Answer
The number of species / how many species there are (1)
OR
The diversity/variety/types/kinds /number of life/organisms/animals & plants (must have both) (1)
Tropical Biomes
Characteristics | Tropical Rain Forest | Tropical Monsoon Forest |
|---|---|---|
Location | Low latitudes Within the Tropics 23.5° north and south of the equator Amazon in South America, New Guinea, Southeast Asia, Zaire Basin | 5° to 30° north and south of the equator India, Central America, Southeast Asia |
Annual Precipitation | Over 2000mm | Between 700 - 2000mm |
Temperature Range | 26-28°C | 30-45°C in summer and 15-30°C in winter |
Seasons | No seasons: hot and wet all year round | Three seasons Cool, dry Hot, dry Rainy season |
Growing Season | All year round | During the rainy season and cool, dry season |
Soils | Infertile due to leaching and rapid uptake of nutrients by plants |
|
Biodiversity | Approx. 50% of the world's plant and animal species live within the rainforest biome Four layers of vegetation: mahogany, teak trees, lianas, orchids Toucans, jaguars, frogs, snakes | High levels of biodiversity Hardwood, deciduous trees, teak, mahogany, lianas and orchids Monkeys, parrots, jaguars, panthers, snakes, frogs |
Temperate and Boreal (Taiga) Forest Biomes
Characteristics | Temperate Forest | Boreal (Taiga) Forest |
|---|---|---|
Location | Between 40°- 60° north and south of the equator Western Europe, northeast USA, Eastern Asia | Between 50°- 60° north and south of the equator Canada, Russia, Scandinavia |
Annual Precipitation | 750-1500mm (all year round) | 300-900mm (all year round) |
Temperature Range | Over 0° C in winter and summer between 20°C-25° C | -30°C in winter and up to 20°C in summer |
Seasons | Four seasons of equal length | Two main seasons: winter and summer |
Growing Season | 6-8 months | 2-3 months |
Soils | Fertile soils 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 | Wide range of animals and plants higher biodiversity than boreal forests Deciduous trees: beech, oak, birch Deer, rabbits, squirrels, bears | Less biodiverse than temperate forests Coniferous trees Squirrels, bears, reindeer, wolves |
Hot Deserts
Characteristics | Hot Desert |
|---|---|
Location | 15° - 30° north and south of the equator North Africa - Sahara, Southern Africa - Kalahari and Namib, Australia, Middle East |
Annual Precipitation | Below 250mm |
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 |
Biodiversity | Low diversity Cacti, yucca Spiders, scorpions, camels, meerkats |
Grassland Biomes
Characteristics | Savanna | Temperate Grasslands |
|---|---|---|
Location | North and south of the tropical and monsoon forest biomes 5° - 30° north and south of the equator Central Africa - Tanzania, Kenya | The 'veldts' of South Africa, the 'pampas' of Argentina, and 'steppes' of Russia and the 'plains' of the USA 40°- 60° north and south of the equator |
Annual Precipitation | 800-900mm | 250-750mm |
Temperature Range | 15°C to 35°C | -40°C to 40°C |
Seasons | Wet and dry season | Four seasons |
Growing Season | During the wet season (4-5 months) | During the summer (dependent on temperature) |
Soils | Free draining with a thin layer of humus Not very fertile most nutrients near the surface | Fertile soil |
Biodiversity | Wide range of plant and animal species Grasses, baobab and acacia trees Zebras, elephants, giraffes Greatest diversity of hoofed animals | Large numbers of plant and animal species Grasses, sunflowers Bison, antelopes, rabbits Grasses and trees |
Tundra Biomes
Characteristics | Tundra |
|---|---|
Location | North of the Arctic Circle and Antarctica |
Annual Precipitation | Less than 250mm |
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 Snowy owls, snow bunting and tundra swan Arctic foxes, hares and wolves Polar bears, musk ox and caribou Small grasses, mosses, lichen |
Worked Example
State two characteristics of the temperate forest biome
(2 marks)
Answer
Deciduous / seasonal trees (1)
Seasonal climate / four seasons / idea of seasons (‘warmer summer but colder winter’) (1)
Hotter/wetter than another named biome (‘cooler than rainforest’) (1)
May rain throughout year (1) or all year round (1)
Northern limit of approximately 40 to 60 degrees (1)
Southern limit approximately 30 to 40 degrees (1)
Covers UK / much of Europe / valid named countries (1)
Structure of forest e.g. mentions multiple layers (1)
Broad leaves (1)
High Biodiversity – relative to other named biome (1)
Detail of food chain e.g. ‘top predator is brown bear’ (1)
Nutrient rich soils (1) or ground litter (1)
Examiner Tips and Tricks
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
Impact of Local Factors on Biome Distribution
The distribution of biomes can also be affected by local factors including:
Altitude: Increases in altitude lead to decreases in temperature
Rock and soil type: soil pH (acidity/alkalinity) affects the plant species which will grow and the mineral content of soil is affected by the types of rock
Drainage: the moisture content of the soil affects the plant species which will grow
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
Biotic and abiotic
All biomes consist of biotic and abiotic elements
These components are all interlinked and changes in one can lead to changes in the others this is known as interdependence
Interdependence
Soil (abiotic) is formed from dead plant and animal (biotic) together with minerals and particles from weathered rock (abiotic)
Soil, water and solar energy (abiotic) then provides nutrients and moisture for plants (biotic) to grow
As part of photosynthesis plants take in CO2 and release oxygen which ensures that the balance of gases in the atmosphere is maintained
The plants (biotic) are then eaten by animals (biotic) which also eat each other
When they die the nutrients are then returned to the soil (abiotic) through decomposition
If one component of this system is affected, for example vegetation being cut down, this will impact on all the other components
Fewer nutrients will be added to the soil through decomposition
There will be less food and fewer habitats so animal species will decrease
The soil will not be protected from sun and rain so there will be increased soil erosion
CO2 will increase
There will be less transpiration and therefore, less precipitation
Worked Example
Explain one way in which vegetation helps soil to develop
(2 marks)
Answer
Soils depend on plants for nutrients (1), delivered by decomposition/death of litter/roots/dead plants (1)
Plants biologically weather the bedrock (1) creating the fragments/particles which make up soil (1)
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