paper 3

5. – The layer of dead leaves and organic matter on the forest floor; this nutrient store is very small in tropical rainforests due to rapid decomposition.
7. – The pessimistic theorist who argued that population growth would eventually outstrip food supply, leading to famine.
8. – Cone-bearing, needle-leaved trees adapted to cold, snowy climates.
11. – The sub-arctic forest biome dominated by coniferous, evergreen trees.
12. – The global ecological system integrating all living beings and their relationships; Earth's "life support system".
14. – The process of replanting and rebuilding a degraded ecosystem to return it to its natural state.
15. – The pine beetle is an example of this biological threat to the cold taiga biome, which is worsening due to milder winters.

1. – The clear-cutting or removal of forest canopy, a major direct threat to the tropical rainforest.
2. – The commercial extraction of resources for economic gain, often at the expense of the environment.
3. – A global-scale ecosystem determined primarily by climate, such as a tropical rainforest or tundra.
4. – a controversial method used to extract shale gas by injecting high-pressure liquid.
6. – A mixture of sand, clay, water, and bitumen mined in the Canadian taiga to produce heavy oil.
9. – Sustainable, low-impact travel that supports local conservation and provides income to forest communities.
10. – Energy resources that are naturally replenished on a human timescale, such as wind or solar.
12. – The optimistic theorist who argued that population growth drives agricultural and technological innovation ("necessity is the mother of invention").
13. – The heavy metal element used as fuel in nuclear power stations.