Question 1
Paper 2Medium16 marksThree temperate sites were managed using different approaches to restoration: planting non-native trees, allowing native forest to regenerate, or restoring a peat-forming wetland by re-establishing waterlogged conditions. Waterlogging at the wetland limits the decomposition of dead plant material.
Each approach was studied at one site. Three plots were sampled at each site. Figure 1 shows the mean net increase in carbon stored in vegetation and soil relative to the start of restoration. Table 1 shows the mean number of native plant species recorded per 20 quadrats after 15 years, averaged across the three plots.
Table 1
| Restoration approach | Mean number of native plant species per 20 quadrats after 15 years |
|---|---|
| Non-native tree plantation | 7 |
| Native forest regeneration | 19 |
| Restored peat-forming wetland | 15 |
Identify the restoration approach with the greatest increase in carbon stored after 10 years.
Calculate the mean annual increase in carbon stored in the restored peat-forming wetland between years 5 and 15. Give your answer with a unit.
Describe and compare the changes in carbon stored in the three restoration approaches over the 15-year period.
Explain how tree-based restoration and restoration of a peat-forming wetland can each increase carbon storage.
A project manager argues that non-native tree plantations should be chosen as the best option, considering carbon storage and native plant diversity over the first 15 years. Evaluate this claim using Figure 1 and Table 1.
Suggest one limitation of the investigation’s design and explain how it could affect the comparison of restoration approaches.