Ecosystem Characteristics (Cambridge (CIE) IGCSE Geography)

Revision Note

Bridgette Barrett

Written by: Bridgette Barrett

Reviewed by: Jenna Quinn

Tropical Rainforest Ecosystem Characteristics

  • The Tropical rainforest (TRF) biome is mainly found in a band between 15north and 15south of the equator within the equatorial climate zone

  • Covering only 6% of the Earth's surface the main areas of tropical rainforest ecosystem are in the following countries;

    • Amazon which is the largest remaining rainforest on Earth usually associated with Brazil but covers parts of seven other countries

    • Central America including parts of Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama

    • Central Africa including Cameroon, the Central African Republic, the Republic of Congo, the Democratic Republic of Congo (DRC), Equatorial Guinea and Gabon

    • Indo-Malaysia, including Malaysia, Indonesia and a number of other countries in South-East Asia

Biodiversity

  • TRFs contain the highest biodiversity of plants and animals on Earth

    • Estimates range from over 50% to 80% of the world's plant and animal species

    • One 10kmarea can contain up to 1,500 flowering plants, 750 species of trees, 400 species of birds and 150 species of butterflies

Nutrient cycle

  • The TRFs have a continual growing season with high rainfall and temperatures all year round

  • The nutrient cycle is rapid

    • Trees and plants lose their leaves all year round

    • The high level of moisture and high temperatures leads to rapid decomposition and recycling of nutrients

    • Plants grow quickly which leads to a rapid uptake of nutrients from the soil

trf-nutrient-cycle
Tropical rainforest nutrient cycle
  • The result of this rapid nutrient cycle is that the soil in the TRF is not very fertile

Structure of the tropical rainforest 

  • The TRF has five distinct layers

    • Ground layer (0m)

    • Shrub layer (3-4m)

    • Under canopy (15m)

    • Canopy (30m)

    • Emergents (45-55m)

trf-structure
Tropical rainforest structure

Adaptations

  • The plants and animals within the TRF are very well adapted to the climate conditions

Plants

Animals

Waxy leaves with drip tips - these ensure that rainwater runs off the leaf and does not remain which would encourage mould growth or break the leaf

Sloth - algae grow in the fur of the sloth helping to camouflage it

Buttress roots - these large roots above the ground which help to support the very tall trees because the roots below the surface are shallow

Toucan - has a large bill to reach and cut fruit from the branches of trees

Lianas - vines which use the tall trees as support to reach the sunlight

Primates - have prehensile tails to help them climb trees

Epiphytes - these are plants which grow on trunks and branches of trees getting nutrients from air, rain or debris accumulating around the plant

Geckos - have large, flattened toe pads with sticky scales which allow them to grip the smooth tree trunks

Straight, smooth trunks - to reduce the number of epiphytes using the tree

Stick Insects - their stick and leave shapes help them to be camouflaged

Examiner Tips and Tricks

You may be asked to describe the rainforest vegetation characteristics. As well as adaption features remember to include information about the different layers and heights of each layer.

Food web

  • As in all ecosystems the TRF has a complex food web which includes

    • Producers

    • Primary consumers

    • Secondary consumers

    • Tertiary consumers

trf-food-web
Tropical rainforest food web

Worked Example

Study Fig 1, which is a diagram showing information about a tropical rainforest ecosystem in an area of equatorial climate

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Suggest reasons why some animals live in the canopy but others live in the ground cover in a tropical rainforest.

[3 Marks]

  • You need to consider the adaptations and diets of the animals which may lead them to live in a specific layer

Answer

  • Some are able to climb/fly whereas others are not [1]

  • Some need shelter/protection [1]

  • Food supplies available (in canopy/at ground level) [1]

  • Different habitats/nesting areas etc [1]

Hot Desert Ecosystem Characteristics

  • Hot desert biomes are mostly found in a band around the Tropic of Cancer and Tropic of Capricorn

  • Approximately 20% of the Earth's surface is covered by hot desert ecosystems including in the following areas;

    • North America - the Mojave and Sonoran Deserts of the USA and Mexico

    • South America - the Sechura Desert in Peru and the Atacama Desert in Chile

    • Africa - the Sahara, Kalahari, Namib and Somali Deserts

    • Middle East - the Arabian Desert 

    • Asia - the Dasht-e Lut in Iran, the Gobi, Turkestan, Thar and Taklamakan Deserts

    • Oceania - the Australian Desert

Biodiversity

  • Hot deserts have one of the lowest biodiversity of plants and animals on Earth

  • The hot desert biome supports approximately 5000-6000 plant species, many invertebrates and up to 20 species of bird

Nutrient cycle

  • The growth of plants is limited due to the extremes of temperature and lack of water

  • The nutrient cycle is very slow

  • Most nutrients are stored in the soil

desert-nutrient-cycle
Hot desert nutrient cycle
  • Due to a lack of organic matter the soils are coarse, sandy and low in nutrients

Adaptations

  • To be able to survive the extreme temperatures and lack of rainfall the plants and animals are extremely well adapted

Plants

Animals

Low growing - this helps to avoid water loss due to strong winds

Camels have a range of adaptations including two sets of eyelashes and nostrils which close to keep sand out of their ears and noses. They also store fat in their humps so they can survive for long periods without food or water

Thick stems - used to store water

Fennec Fox - have large ears which help them to lose heat

Shallow roots - these spread out near the surface to catch whatever rain falls

Burrowing - many animals burrow to avoid the intense day time heat

Long roots - some plants have long tap roots instead of shallow roots to reach water deep underground

Insects and reptiles have waterproof skin to reduce water loss

Small leaves or needles - the smaller surface area reduces water loss

Nocturnal - some animals hunt at night to avoid the daytime heat

Food web

  • As in all ecosystems hot deserts have a complex food web which includes

    • Producers

    • Primary consumers

    • Secondary consumers

    • Tertiary consumers

desert-food-web
Hot desert food web

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Bridgette Barrett

Author: Bridgette Barrett

Expertise: Geography Lead

After graduating with a degree in Geography, Bridgette completed a PGCE over 25 years ago. She later gained an MA Learning, Technology and Education from the University of Nottingham focussing on online learning. At a time when the study of geography has never been more important, Bridgette is passionate about creating content which supports students in achieving their potential in geography and builds their confidence.

Jenna Quinn

Author: Jenna Quinn

Expertise: Head of New Subjects

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.