Explain how seasonal changes in light intensity can affect the distribution of a plant population in a deciduous woodland.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
In a deciduous woodland, the trees lose their leaves in autumn and regrow them in spring. Small flowering plants, such as bluebells, are found growing on the woodland floor.
Model answer (4 marks)
Light intensity is an abiotic factor that influences plant distribution.
In spring and early winter the deciduous trees have shed their leaves, so the canopy is open and light intensity on the woodland floor is high.
During summer the leafed canopy blocks much of the sunlight, reducing light intensity at ground level.
Plants such as bluebells therefore grow and flower early in spring, when light is abundant, and their distribution is concentrated in the woodland where this seasonal light is available.
In spring and early winter the deciduous trees have shed their leaves, so the canopy is open and light intensity on the woodland floor is high.
During summer the leafed canopy blocks much of the sunlight, reducing light intensity at ground level.
Plants such as bluebells therefore grow and flower early in spring, when light is abundant, and their distribution is concentrated in the woodland where this seasonal light is available.
Examiner tips
- Use the term "light intensity" as an abiotic factor. Mention the seasonal change in canopy cover. Explain why early‑spring flowering gives a competitive advantage. Keep each point brief and directly linked to the marks scheme.
Common mistakes
- Confusing light intensity with temperature. Failing to mention the canopy’s role in blocking light. Giving a general statement about plant growth without linking it to seasonal light changes.
Mark scheme (4 marks)
- Light intensity is an abiotic factor that affects distribution of plant populations
- In spring / winter, trees have no leaves so light intensity on the woodland floor is high
- In summer, the tree canopy blocks light, reducing light intensity at ground level
- Plants such as bluebells grow / flower early in spring to take advantage of higher light intensity for photosynthesis, so their distribution is concentrated in woodland where this seasonal light is available
Key terms in this question
Related
- All Pearson Edexcel International GCSE Biology (4BI1) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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