A student investigates the biodiversity of two woodland areas. One woodland has been managed by humans for timber production. The other woodland has been left undisturbed for over 100 years. Describe how the student could use quadrats to compare the plant species diversity of the two woodland areas.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
1. Randomly place a set of identical quadrats in each woodland.
2. Use the same number of quadrats and the same size for both sites.
3. In each quadrat record every plant species present.
4. Repeat the sampling to obtain several quadrats per site and calculate the mean number of species per quadrat.
5. Compare the mean (or total) species counts between the two woodlands to assess which has higher biodiversity.
2. Use the same number of quadrats and the same size for both sites.
3. In each quadrat record every plant species present.
4. Repeat the sampling to obtain several quadrats per site and calculate the mean number of species per quadrat.
5. Compare the mean (or total) species counts between the two woodlands to assess which has higher biodiversity.
Examiner tips
- Use the word ‘randomly’ to show unbiased sampling.
- State that the same quadrat size and number must be used for both sites.
- Mention calculating a mean species count to summarise the data.
- Compare the means or totals to decide which woodland is more diverse.
Common mistakes
- Using different quadrat sizes or numbers for the two sites.
- Failing to repeat the sampling or calculate a mean.
- Not specifying that species are recorded in each quadrat.
Mark scheme (5 marks)
- Place quadrats at random positions in each woodland area
- Use the same number / size of quadrats in each woodland area
- Record / count the number of different plant species (in each quadrat / area)
- Repeat the process and calculate a mean number of species (per quadrat / per area)
- Compare the total number of different species / mean number of species between the two woodland areas to determine which has greater biodiversity
Key terms in this question
quadrat · biodiversity · species
Related
- All AQA A-Level Biology (7402) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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