Deforestation — AQA GCSE Combined Science
Test yourself on Deforestation with AQA GCSE practice questions.
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Deforestation explained
Deforestation means removing large areas of forest, usually in tropical regions such as the Amazon basin.
Read the full explanation
The specification requires specific reasons for this large-scale removal. Forests are cleared to provide land for cattle and rice fields, and to grow crops for biofuels. For example, land cleared for cattle grazing provides beef, while flooded fields are used to grow rice to feed growing populations. Additionally, crops like palm oil or sugar cane are grown to produce biofuels as an alternative energy source. These activities are driven by demand for food and fuel. However, removing trees reduces the carbon stored in living biomass, releases carbon dioxide when wood is burned or decays, and severely reduces biodiversity.
provide land for cattle and rice fields
Deforestation is the large-scale removal of trees from an area. One major reason people clear forest is to obtain land for farming. Two specific uses are grazing cattle and growing rice. Cattle need large areas of grass or pasture, so forest is cut down and often burned to create fields for herds. Rice grows best in flooded paddy fields, so flat, waterlogged land is needed; forest may be cleared and the land flooded to create these paddies. Both activities remove the trees that absorb carbon dioxide during photosynthesis, store carbon in biomass, provide habitats and hold soil together with roots. The cleared land may then be used for farming, but the loss of forest reduces biodiversity, increases carbon dioxide in the atmosphere and can lead to soil erosion and flooding.
grow crops for biofuels
Biofuels are fuels made from plant material or animal waste. To produce them, land is often cleared of forest so that crops such as sugar cane, maize or oil palm can be grown. These crops store energy from sunlight in their tissues. The plant material is harvested and processed to make fuels such as ethanol or biodiesel, which can be burned instead of fossil fuels. Growing biofuel crops can reduce reliance on non-renewable fossil fuels, but clearing forest for them removes trees that absorb carbon dioxide, destroys habitats and reduces biodiversity. If the forest is burned, carbon stored in the trees is released quickly. There is also a conflict because land used for biofuel crops cannot be used to grow food.
Your focus
- Identify the main reasons for large-scale deforestation in tropical areas as cattle, rice fields and biofuels.
- Explain how each reason meets human demand for food or fuel.
- Relate deforestation to its effects on carbon stores, biodiversity and the environment.
Show all 9 objectives
- State that deforestation can provide land for cattle grazing and rice fields.
- Describe how clearing forest creates pasture for cattle and flooded fields for rice.
- Explain how this land-use change affects carbon dioxide levels, biodiversity and soil.
- State that crops can be grown to produce biofuels.
- Describe how biofuel crops are processed into fuels such as ethanol or biodiesel.
- Explain the advantages and disadvantages of clearing forest to grow biofuel crops.
Deforestation exam tips
Marking Points
- Deforestation is the large-scale removal of trees from forested areas, especially in tropical regions.
- Land is cleared to provide grazing for cattle.
- Land is cleared to provide space for rice fields to feed growing populations.
- Land is cleared to grow crops from which biofuels can be produced.
- The consequences of deforestation include loss of carbon stores, increased carbon dioxide release and reduced biodiversity.
- Deforestation is the clearing of forest to make land available for other uses, including agriculture.
- Cattle farming requires large areas of grazing land, so forest is removed to create pasture.
- Rice farming requires flooded paddy fields, so forest may be cleared and the land flooded.
- Removing trees reduces carbon dioxide absorption by photosynthesis and releases stored carbon when trees are burned or decompose.
- Loss of forest reduces habitats and biodiversity, and roots no longer bind the soil, so erosion can increase.
- Biofuels are fuels produced from plant material or animal waste.
- Land is cleared to grow crops such as sugar cane, maize or oil palm for biofuel production.
- Biofuel crops store energy from sunlight, which can be converted into fuels such as ethanol or biodiesel.
- Using biofuels can reduce the use of non-renewable fossil fuels.
- Deforestation for biofuel crops reduces carbon dioxide absorption, destroys habitats and reduces biodiversity.
- Land used for biofuel crops may compete with land for food crops.
Examiner Tips
- 💡Memorise the specific reasons for deforestation required by the specification: cattle, rice fields, and crops for biofuels.
- 💡Balance each reason with its environmental effect, for example clearing land for cattle provides food but removes a vital carbon store.
- 💡Link each land use to a specific farming need: pasture for cattle, flooded fields for rice.
- 💡Explain the consequence chain: trees removed → less photosynthesis → less carbon dioxide absorbed → more carbon dioxide in the atmosphere.
- 💡Use the term biodiversity when describing habitat loss, and refer to soil erosion when roots are removed.
- 💡Name at least one biofuel crop, such as sugar cane or maize, to make your answer specific.
- 💡Compare biofuels with fossil fuels: biofuels are renewable, but their production can still cause deforestation.
- 💡Explain both a benefit and a drawback of growing biofuel crops to show balanced understanding.
Common Mistakes
- Giving non-specification reasons such as timber or roads; correction: stick to the specified reasons which are cattle, rice fields, and crops for biofuels.
- Confusing deforestation with climate change itself; correction: deforestation is the removal of forest, while climate change is a consequence that can follow from it.
- Stating that deforestation adds carbon dioxide only because trees stop photosynthesising; correction: carbon dioxide is also released when cleared vegetation is burned or decomposed by microorganisms.
- Thinking deforestation only affects the atmosphere; correction: it also destroys habitats, reduces biodiversity and can cause soil erosion and flooding.
- Confusing cattle grazing with rice growing; correction: cattle need dry pasture, while rice needs flooded paddy fields.
- Assuming cleared land always stays fertile; correction: without tree roots and leaf litter, nutrients are leached and soil may be eroded.
- Thinking biofuels are completely carbon neutral; correction: clearing and burning forest releases carbon dioxide, so the overall effect may not be neutral.
- Confusing biofuels with fossil fuels; correction: biofuels are made from recently living plant material, while fossil fuels formed over millions of years.
- Ignoring the food-versus-fuel conflict; correction: land used for biofuel crops cannot also grow food crops.