Knowledge Organiser: Tropical Rainforests
Key Terms
- Deforestation: Large-scale permanent removal of forest — 17% of Amazon lost since 1970
- Biodiversity: Variety of species — Amazon holds 10% of all species on Earth
- Nutrient cycling: Nutrients circulate through biomass, not stored in thin soil
- Interdependence: All ecosystem parts depend on each other — remove one, many are affected
- Carbon sink: Amazon stores 150–200 billion tonnes of carbon
- Tipping point: 20–25% deforestation may trigger irreversible savannification
- REDD+: International payments for keeping forests standing — Norway paid Brazil $1.2bn
- Laterite: Hard, infertile soil left after forest is cleared and nutrients leach away
Amazon Key Facts
- 5.5 million km² across 9 countries (60% in Brazil)
- 10% of all species on Earth; 40,000 plants, 1,300 birds, 3,000 freshwater fish
- 400+ indigenous tribes; ~70 uncontacted
- 150–200 billion tonnes of carbon stored
- 20 billion tonnes of water vapour per day ("flying rivers")
- 25% of Western medicines derived from rainforest plants
- 17% deforested since 1970; tipping point at 20–25%
Deforestation Causes (SLIMEH)
- S — Soya farming ($33bn/year; 25m hectares; BR-163 highway)
- L — Logging (80% illegal; mahogany; roads open forest)
- I — Indigenous displacement (poverty; slash-and-burn)
- M — Mining (Serra Pelada goldmine; Carajás iron ore)
- E — Energy (Belo Monte Dam; 500 km² flooded; 20,000 displaced)
- H — Highways and ranching (Trans-Amazon Highway; cattle = 70% of clearing)
Management Strategies + Evidence
- Satellite monitoring (INPE): Reduced deforestation 83% (2004–2012)
- Indigenous territories: 10x lower deforestation than unprotected areas
- Forest Code: 80% of Amazon land holdings must remain forested
- REDD+ / Amazon Fund: Norway paid $1.2bn; payments tied to measurable reductions
- Key lesson: Strategies only work with political will — proven by 2019 rise and 2023 fall
Common Mistakes
- Saying TRF soils are fertile: Rainforest soils are thin and infertile — nutrients are locked in the biomass, not the soil; clearing causes rapid leaching
- Listing causes without explaining them: Don't just write "cattle ranching causes deforestation" — explain the economic driver (cheap land, beef export demand) and the scale (70% of Amazon clearance)
- Forgetting the tipping point: Deforestation beyond 20–25% may trigger irreversible savannification — this is a key evaluation point examiners reward
- Ignoring conflicts between stakeholders: Management questions require you to show tension — e.g. farmers need land vs indigenous communities need forest vs global need for carbon sink
Memory Aid
- C — Climate: hot (26–28°C) and wet (2,000 mm+) all year round
- O — Organisation: four distinct layers (emergent, canopy, understorey, forest floor)
- L — Life: extraordinary biodiversity — 10% of all species on Earth
- D — Dependence: deep interdependence — remove one component and the system unravels
- S — Soya farming (world's largest exporter, $33bn/year, 25 million hectares)
- L — Logging (80% illegal; mahogany, teak; logging roads bring further deforestation)
- I — Indigenous displacement (poverty and landlessness — smallholder slash-and-burn)
- M — Mining (Serra Pelada gold rush; Carajás iron ore; garimpo mercury pollution)
- E — Energy (Belo Monte Dam — 500 km² flooded, 20,000 people displaced)
- H — Highways and ranching (Trans-Amazonian Highway; BR-163; cattle = 70% of clearing)