The tropical rainforest ecosystem Cambridge IGCSE Geography revision
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In plain words
A tropical rainforest is the opposite of Antarctica: hot, wet and crowded with more kinds of living things than anywhere else on land. It grows in layers, each with its own light, its own plants and its own animals.
7 things to know
- Tropical rainforests are found near the Equator, mostly between the Tropics of Cancer and Capricorn: the Amazon basin, the Congo basin and South-East Asia.
- The equatorial climate is hot all year, about 26 to 28 °C, with very little change from month to month, and very wet, with more than 2000 mm of rain a year.
- The sun is overhead or nearly so all year. It heats the ground, the warm, moist air rises (low pressure), cools and condenses, and heavy convectional rain falls, often in the afternoon.
- Structure, from the top: emergents, the tallest trees, which rise above the rest; the canopy, a continuous layer of leaves that takes most of the light; the under-canopy; the shrub layer; and the dark forest floor.
- The soil is poor. Nutrients are held in the plants, not the soil. Leaves fall, rot quickly in the heat and damp, and the nutrients are taken up again at once by shallow roots.
- Plant adaptations: tall, straight trunks to reach the light; buttress roots to support them; leaves with drip tips to shed water; lianas that climb other trees.
- Animal adaptations: living in the canopy where the food is, strong limbs or gripping tails for climbing, camouflage, and being active at night.
Worked example
Explain why it rains almost every afternoon in a tropical rainforest.
- In the morning the overhead sun heats the ground and the air above it, and water evaporates from the forest.
- The warm, moist air rises. As it rises it cools.
- The water vapour condenses into tall clouds, and heavy rain falls in the afternoon. This is convectional rainfall.
Tips and tricks
- The forest looks rich, but its soil is poor. The nutrients are in the trees. That is why cleared rainforest land stops growing crops after a few years.
- For adaptations, say what the feature is and what it is for: "drip tips, so that water runs off quickly".
It lands in your notebook with its questions as flashcards.
The tropical rainforest ecosystem: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
Where are tropical rainforests found?
Between the two Tropics.
What type of rainfall is typical of a tropical rainforest?
The heated ground makes air rise.
Which layer of the rainforest receives the most sunlight?
Very little light gets through to the ground.
What is the purpose of buttress roots?
The soil is shallow, so trees need extra support.
Where are most of the nutrients in a rainforest stored?
They are recycled quickly from fallen leaves.
Why do leaves in the rainforest have drip tips?
Wet leaves would grow mould and block light.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 10 marks. Write your answers on paper, then check them.
The tropical rainforest ecosystem
Cambridge IGCSE Geography 0460 · 10 marks · papermunch.org
Name ______________________________ Date ______________
Describe the climate of a tropical rainforest.[3]
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It is hot all year, around 27 °C, with little variation. Rainfall is very high, over 2000 mm a year. Rain falls on most days, often as heavy afternoon storms.
Explain two ways in which rainforest trees are adapted to their environment.[4]
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Buttress roots spread out above the ground to support the very tall trunks. Leaves have drip tips, so that heavy rain runs off quickly. (Also: tall straight trunks to reach sunlight.)
Explain why rainforest soils are poor even though the vegetation is dense.[3]
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Most of the nutrients are stored in the plants. Fallen leaves decompose quickly and the nutrients are taken up again at once. Heavy rain washes any nutrients left in the soil away.
Answers: The tropical rainforest ecosystem
- 1. It is hot all year, around 27 °C, with little variation. Rainfall is very high, over 2000 mm a year. Rain falls on most days, often as heavy afternoon storms.
- 2. Buttress roots spread out above the ground to support the very tall trunks. Leaves have drip tips, so that heavy rain runs off quickly. (Also: tall straight trunks to reach sunlight.)
- 3. Most of the nutrients are stored in the plants. Fallen leaves decompose quickly and the nutrients are taken up again at once. Heavy rain washes any nutrients left in the soil away.