Lecture Notes: Amazon Rainforest Case Study

Introduction

• Focus on the Amazon Rainforest as a major case study of tropical rainforests (TRF).
• TRFs are located between the Tropic of Cancer and the Tropic of Capricorn.
• Average temperature: 27°C; Annual rainfall: 2,500mm.
• Linked to the Hadley cell: rising warm air cools, leads to daily rainfall.

Rainforest Structure

• Forest Floor (Shrub Layer): Only 2% sunlight.
• Under Canopy: More sunlight and rain than the forest floor.
• Canopy: Dense layer of vegetation, looks like a blanket from above.
• Emergent Layer: Over 40 meters high, trees seen from above.

Vegetation Adaptations

• Buttress Roots: Trees have wide, stable bases as roots don’t go deep due to infertile soil.
• Vines (Lianas): Grow up trees to access sunlight.
• Epiphytes: Parasitic plants feeding off trees.
• Leaves: Feature drip tips to shed water and prevent mold; shed year-round contributing to rapid decomposition and nutrient cycling.

Animal Adaptations

• Howler Monkey:
  • Long limbs for easy movement across canopy.
  • Prehensile tail for gripping branches.
• Three-Toed Sloth:
  • Moves slowly and is camouflaged; moss grows on its back.

Reasons for Deforestation

• Logging: Economic reasons, timber extraction.
• Mining: Gold mining using opencast methods.
• Farming: Cattle farming is the primary cause; leads to soil infertility through leaching.

Impacts of Deforestation

• Economic: Income generation and debt reduction.
• Social: Displacement of native people; exposure to new diseases.
• Environmental:
  • Increased CO2 emissions.
  • Soil erosion due to lack of tree cover.
  • Loss of biodiversity.

Value of Rainforests

• Goods:
  • Food, perfumes, timber.
  • Medicinal plants: 25% of UK prescriptions contain rainforest derivatives.
• Services:
  • Natural carbon storage, aids in fighting climate change.

Management Strategies

1. Debt Reduction (Best Strategy):
   • Rich countries cancel debts in exchange for carbon credits.
   • Legal agreements to prevent deforestation.
2. Ecotourism:
   • Educational and conservation-focused tourism.
   • Small-scale economic benefit.
3. Selective Logging (Least Preferred):
   • Targeting mature trees damages surrounding trees.
   • Not sustainable as 75% of trees are felled within three years.

Conclusion

• The case study illustrates the complexity of managing the Amazon and similar ecosystems.
• Emphasis on debt reduction as the most effective management strategy.
• Information applicable to other tropical rainforests.