Deforestation: Causes and Effects
Learn the main causes and effects of deforestation for AQA GCSE Biology, including habitat loss, reduced biodiversity and increased carbon dioxide.
Deforestation is the large-scale removal of forests. It is mainly caused by clearing land for agriculture and biofuel crops. Its effects include habitat loss, reduced biodiversity and increased carbon dioxide levels in the atmosphere.
What causes deforestation?
For AQA GCSE Biology, the key causes of large-scale deforestation in tropical areas are:
- Cattle farming: forests are cleared to provide land where cattle can graze.
- Rice fields: land is cleared so that rice can be grown.
- Biofuel crops: trees are removed to make space for crops that can be used to produce fuels.
Other human activities can also reduce the land available to organisms, but these are the specific examples linked to tropical deforestation in this topic.
What are the effects?
Reduced biodiversity
Clearing forests destroys habitats. Organisms lose food, shelter and breeding sites, so populations may fall. Some species may become extinct, reducing biodiversity—the variety of different species in an ecosystem.
Forests contain interdependent communities. This means species depend on one another. Removing trees can therefore affect food chains and the stability of the whole ecosystem.
Increased carbon dioxide
Trees remove carbon dioxide from the atmosphere during photosynthesis. With fewer trees, less carbon dioxide is removed. If cleared trees are burned or decay, carbon dioxide is also released.
Higher atmospheric carbon dioxide levels contribute to global warming, which can change habitats and affect where species can survive.
Worked example
Question: Explain how deforestation may reduce biodiversity.
Answer: Deforestation destroys habitats, so organisms lose resources such as food and shelter. Their populations may decrease, and some species may become extinct. Therefore, the variety of species decreases.
Common exam mistake: Do not simply write “deforestation kills animals.” Link the cause to the effect: habitat destruction leads to falling populations or extinction, which reduces biodiversity.
Scope assumed: AQA GCSE Biology 8461 Higher tier. This content is also suitable for Foundation tier and is not marked biology-only. It is part of Ecology on Paper 2.
