Explain effects of deforestation
Deforestation can reduce biodiversity, cause extinction, remove soil protection, increase flooding and raise atmospheric carbon dioxide.
Section 20.2 · Habitat destruction
Exam scope and assessment notes
Core and Extended · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Know that organisms interact with other organisms and their environment.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which outcome is directly linked to reduced root support after deforestation?
What you will learn
- Explain five undesirable effects of deforestation
- Link each effect to a plausible environmental process
Connect tree removal to habitat and soil
Removing forest reduces living space and resources, so fewer species may remain and some may become extinct. Roots help hold soil in place; after trees are removed, exposed soil can be eroded or washed away.
With less interception by leaves and less uptake by roots, more rainwater can reach the ground and flow over it quickly. This can increase flooding. The exact risk depends on local rainfall, slope, soil and land management.
Connect forest carbon with atmospheric carbon dioxide
Trees remove carbon dioxide from the air during photosynthesis and store carbon in biomass. When forests are cleared, less carbon dioxide is removed from the atmosphere; burning or decay of cleared vegetation can release stored carbon. These changes can increase atmospheric carbon dioxide.
Explain the named outcomes separately: loss of habitat reduces biodiversity and can cause extinction; loss of root cover increases soil loss; altered water movement can increase flooding; changed carbon uptake and release can increase atmospheric carbon dioxide.
Pause and explain
How can deforestation increase atmospheric carbon dioxide?
Worked example
After a forest is cleared, heavy rain washes soil into a river and nearby areas flood more often. Explain both observations.
Show the worked solution
- Link soil loss to reduced root support.
- Link flooding to faster surface runoff after tree cover is removed.
Answer Removing trees reduces root support for soil, so rain can erode and carry it away. Reduced interception and water uptake can increase rapid runoff, raising flood risk.
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Explain how deforestation can reduce biodiversity and lead to extinction.
Give me a hint
Start with habitat removal and connect it to species survival.
Compare my reasoning
- Forest organisms lose some of their habitat and resources.
- Some species may no longer survive in the changed area.
Deforestation removes or changes habitat and resources. The number of species may fall, and species unable to survive the change may become extinct.
Look for these in your work
- Habitat change identified
- Biodiversity and extinction distinguished
Explain the connection between deforestation and flooding.
Give me a hint
Think about interception, uptake and surface flow.
Compare my reasoning
- Fewer leaves intercept rain and fewer roots take up water.
- More water may flow rapidly over the ground.
With fewer trees, less rain is intercepted and less water is taken up. More rapid surface runoff can increase flood risk, depending on local conditions.
Look for these in your work
- Water pathway stated
- Flood risk qualified
Give the five undesirable effects of deforestation required by the syllabus.
Give me a hint
Recall biodiversity, extinction, soil, flooding and atmospheric carbon dioxide.
Compare my reasoning
- Reduced biodiversity and extinction.
- Soil loss, flooding and increased atmospheric carbon dioxide.
Deforestation can reduce biodiversity, cause extinction, increase soil loss, increase flooding and increase carbon dioxide in the atmosphere.
Look for these in your work
- All five effects named
- No extra outcomes substituted
Common mistakes
- Listing effects without explaining how they arise
- Saying all cleared forest is immediately burned
- Treating local flood risk as identical in every location
What can you explain now?
Which outcome is directly linked to reduced root support after deforestation?
Compare with the explanation
Greater soil loss through erosion
Roots help hold soil in place.
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Make it stick
Name and explain the five undesirable effects of deforestation in the syllabus.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.