A company clears 25 hectares of tropical forest to make grazing land for cattle. The felled trees are burned and grass grows over the cleared land.
Scientists estimated the carbon dioxide transferred as a result of the land-use change.
| Process | Mass of carbon dioxide in tonnes |
|---|---|
| Removed from the atmosphere by 25 hectares of forest each year | 460 |
| Removed from the atmosphere by 25 hectares of grassland each year | 180 |
| Released when the felled trees are burned | 3600 |
Calculate the additional mass of carbon dioxide added to the atmosphere from this land-use change over four years, compared with leaving the forest unchanged.
Assume that the annual rates in the table remain constant.
At another site, the company proposes leaving the felled trees on the ground instead of burning them.
Explain why the felled trees would still add carbon dioxide to the atmosphere.
84 exam-style questions on AQA GCSE Biology 7.3 Biodiversity and the effect of human interaction on ecosystems, covering 7.3.1 Biodiversity, 7.3.2 Waste management, 7.3.3 Land use, 7.3.4 Deforestation, 7.3.5 Global warming, and 7.3.6 Maintaining biodiversity. Each one has a worked solution and a mark scheme showing where the marks go.