Distribution & Characteristics of Large-Scale Ecosystems (Edexcel GCSE Geography A)
Revision Note
Written by: Jacque Cartwright
Reviewed by: Bridgette Barrett
Distribution of Large-Scale Ecosystems
An ecosystem is a natural environment which includes flora (plants) and fauna (animals) that live and interact in a particular environment
Flora, fauna and bacteria are known as the living or biotic components of the ecosystem
Ecosystems are dependent on non-living or abiotic components and include:
Climate
Soil
Water
The biotic components of the ecosystem have a complex relationship with the abiotic components
Any changes to one component will lead to a change in the other
There are 9 large-scale ecosystems or biomes in Earth's biosphere
Large ecosystem distribution
The main factor affecting ecosystem distribution is climate
Temperatures are lower at higher latitudes, so boreal forests are colder than tropical rainforests
Length of the growing season: longer in warmer climates
Precipitation levels: the global circulation system influences precipitation rates due to descending air
Sunshine hours: lower sunshine hours in tundra ecosystems mean less sunlight for photosynthesis than in tropical rainforests, slowing plant growth
Each ecosystem has its own distinct characteristics, which are determined by its climate
Distribution of the World's Biomes
Distribution of large-scale ecosystems
Characteristics of Large-Scale Ecosystems
Characteristics of Large-Scale Ecosystems
Ecosystem | Location | Precipitation | Temperature | Vegetation | Animals |
|---|---|---|---|---|---|
Tropical rainforest (TFR) | Amazon, Brazil | Total annual rainfall between 2000mm and 2200mm | Small range between 26° and 30° C | Four layers are made up of emergent, canopy, under-canopy, and shrub layers. Lianas grow up the trees, epiphytes grow on the trees, evergreen appearance | Sloths Monkeys Armadillo Snakes Insects |
Temperate forest | UK, Europe | Total annual rainfall is around 1000mm | Temperature range between 4°C and 18°C | Four layers made up of canopy, sub-canopy, herb and ground. Oak is a dominant species. Trees lose their leaves in winter | Rabbits Deer |
Boreal forest | Russia | Total annual rainfall around 500mm | Temperature range between -10°C and 15°C | Evergreen trees with needles (less transpiration) and thick bark (protection from cold), shallow roots | Deer Wolves Black bears |
Tropical grassland | East Africa | Distinctive wet (May–October) and dry seasons | Small temperature range between 25°C and 30°C | Scrub, grasses and occasional trees, e.g. acacia | Many animals migrate long distances in search of food. Wildebeest Giraffes Elephants |
Temperate grassland | Pampas, Argentina | Total annual rainfall around 500mm | Temperature range between 10°C and 18°C | Distinctively devoid of trees. Buffalo grasses | Foxes Skunks Small herds of guanacos Bush dogs Many bird species |
Deserts | Great Sandy Desert, Australia | Very low and unpredictable | Average temperature range between 30°C and 35°C. However, there can be massive difference between day and night | Shrubs, cacti, very little vegetation | Camels Dingoes Kangaroo |
Role of Climate & Local Factors in Ecosystem Distribution
Global climate influence
| Tropics | Polar | Mid-latitudes |
|---|---|---|---|
Sun | More concentrated | Weak | Moderate |
Pressure | Usually low | Usually high | Unsettled |
Air | Warm, humid and rising | Cold, dry and descending | Warm and moist; rises and descends |
Diversity | High biodiversity | Low biodiversity | Moderate |
Influenced by ITCZ | Yes | No | No |
Local factors
Local Factors
Altitude | For every 100 metres of ascent, temperatures decrease by roughly 1°C. The air becomes less dense and does not hold heat as easily |
Prevailing wind | Winds blowing across oceans will bring moisture and rainfall, whereas winds blowing across warmer continents will bring warm, dry air |
Soils | Different vegetation requires different soil types. Thinner soils, such as in the Boreal forests, contain less organic matter and may be more acidic, whereas in the Tropical rainforest, soils are more nutrient-rich because of the decaying litter layer |
Distance from the sea | The land heats and cools faster than the sea. Therefore, coastal areas have a lower temperature range than areas inland. On the coast, winters are relatively mild, and summers are cool. Inland, temperatures are higher in the summer and colder in the winter |
Ocean currents | Warm ocean currents, especially in the North Atlantic, moderate the land temperatures of cold areas |
Relief/Topography | Hills and mountains play a decisive part in local weather patterns, especially where moist air is forced to rise and cool, forming precipitation |
Examiner Tips and Tricks
You may be asked to describe and explain the distribution of biomes. Consider the following:
Biome distribution
Latitude
Country and continent names
Factors which affect the distribution: latitude, altitude, ocean currents, continentality
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