DeforestationSpec B16.1.4, B16.1.5
In short
Deforestation reduces biodiversity, can cause extinction, soil loss and flooding, and raises atmospheric carbon dioxide as fewer trees photosynthesise.
Deforestation is the removal of forests on a large scale. Forests are cleared for timber, for farmland (crops and cattle), for housing and for roads and mining.
You need to be able to state the five undesirable effects of deforestation:
- reduced biodiversity
- extinction
- loss of soil
- flooding
- an increase of carbon dioxide in the atmosphere
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean| Effect | Explanation |
|---|---|
| Reduced biodiversity | Trees provide food and shelter, so many species lose their habitat and food source |
| Extinction | If a species lives only in that forest and cannot move elsewhere, the whole species can die out |
| Loss of soil | Tree roots hold soil together; without them rain washes the soil away (soil erosion) |
| Flooding | Tree roots absorb water and leaves intercept rain; without trees more water runs straight into rivers |
| Increase of carbon dioxide in the atmosphere | Fewer trees take in CO₂ for photosynthesis, and burning or decay of the felled trees releases CO₂ |
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanDo not say trees 'make' oxygen as the main problem. The mark is for fewer trees removing less CO₂ from the air by photosynthesis, plus CO₂ released when wood is burned or decays.
Quick check
Define biodiversity.
Show answer
The number of different species that live in an area.
Give three reasons for habitat destruction.
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Housing, crop and livestock production; extraction of natural resources; freshwater and marine pollution.
Supplement How does deforestation lead to flooding?
Show answer
Fewer roots and leaves to absorb water, so more water runs into rivers.
Supplement How does deforestation increase carbon dioxide in the air?
Show answer
Fewer trees photosynthesise, and burning or decay of trees releases CO₂.
Written and checked against the Cambridge IGCSE Combined Science (0653) specification · Updated October 2026