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Ecosystems

Tropical rainforests and coral reefs at risk

  • 3 things to know
  • Component 3 Section B

Overview

Main causes of tropical deforestation, amazon dieback tipping point and local impacts of rainforest clearance.

What you need to know

Answer each one before you reveal it.

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Key term

Why are tropical rainforests among the most biodiverse ecosystems?

Key term

Name the main causes of tropical deforestation.

Numbers

Quantify recent deforestation in the Brazilian Amazon.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Why are tropical rainforests among the most biodiverse ecosystems?

    Model answer

    Rainforests are warm, wet and stable, so growth continues all year and niches are numerous. Around half of all terrestrial species live on the 6% of land they cover.

  2. 2

    Name the main causes of tropical deforestation.

    Model answer

    Cattle ranching, soya and palm oil cultivation, logging and road building drive most clearance. Mines and dam construction remove further areas.

  3. 3

    Quantify recent deforestation in the Brazilian Amazon.

    Model answer

    Brazil's national monitoring recorded around 13,000 km² of Amazon clearance in the year to July 2021. Rates then fell sharply, to about 6,300 km² in 2023–24 and about 5,800 km² in 2024–25.

  4. 4

    What is the Amazon dieback tipping point?

    Model answer

    Rainforest recycles much of its own rainfall, so clearance reduces regional rainfall. Beyond an estimated 20% to 25% loss the Amazon could shift towards savanna.

  5. 5

    How does rainforest loss affect the global carbon cycle?

    Model answer

    Cleared trees release carbon dioxide as they are burned and as they decay. Loss of the forest also removes a sink that absorbed billions of tonnes of carbon each year.

  6. 6

    What are the local impacts of rainforest clearance?

    Model answer

    Soils are exposed to heavy rain and erode within a few seasons. Indigenous communities lose the forest they depend on for food, medicine and shelter.

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