Tropical rainforests

• Ecological features:

  • climate is relatively stable over long periods of time
  • huge number of specially adapted species
  • high light levels = high photosynthesis rates
  • constant warm temperatures
  • regular high rainfall
  • low soil depth and low nutrient levels due to fast decomposing rate and nutrients are quickly reabsorbed
  • lots of canopy variation - light and height
• Importance:

  • high biodiversity - importance list from before
  • forest resources - timber (house construction), food (chocolate), fibres (cotton, hemp), medicines
  • climate maintenance - increase downwind rainfall, carbon sequestration (carbon sink)
  • soil maintenance - tree cover and roots prevent soil erosion
• Threats:

  • fuelwood collection
  • timber harvesting
  • clearance for alternative land use
  • subsistence agriculture - slash and burn
  • commercial agriculture - cash crops and cattle
  • mineral extraction - iron, gold, silver etc
  • reservoirs - hydroelectric power
  • climate change - forest fires, drought
  • tourism
• Conservation efforts:

  • legislation
  • laws against land conversion
  • illegal logging
  • national parks and protected areas
  • selective logging and replanting
  • mature trees carefully selected
  • ecotourism
  • jungle cruises
• Example:

  • Daintree Rainforest Australia
  • 180 million years old
  • threatened by urban development