Tropical Rainforests

• The tropical rainforest (TRF) biome is mainly found in a band between 15° north and 15° south of the equator within the equatorial climate zone
• Tropical rainforests cover only 6% of the Earth's surface
• Main areas of tropical rainforest ecosystem

  • Amazon (largest remaining rainforest on Earth, usually associated with Brazil but covers parts of seven other countries)
  • Central America (including parts of Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama)
  • Central Africa (including Cameroon, the Central African Republic, the Republic of Congo, the Democratic Republic of Congo (DRC), Equatorial Guinea and Gabon)
  • Indo-Malaysia (including Malaysia, Indonesia and a number of other countries in South-East Asia)
• Tropical rainforests are located in low latitudes, within the Tropics, 23.5° north and south of the equator
• Tropical rainforest (TRF) biome

  Mainly found in a band between 15° north and 15° south of the equator within the equatorial climate zone
• Tropical rainforest ecosystem covers only 6% of the Earth's surface
• Main areas of tropical rainforest ecosystem

  • Amazon (largest remaining rainforest on Earth, covers parts of 7 countries)
  • Central America (including parts of Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama)
  • Central Africa (including Cameroon, the Central African Republic, the Republic of Congo, the Democratic Republic of Congo (DRC), Equatorial Guinea and Gabon)
  • Indo-Malaysia (including Malaysia, Indonesia and other countries in South-East Asia)
• Tropical rainforest climate characteristics

  • Annual precipitation over 2000mm
  • Temperature range 26-28°C, low diurnal range of about 7°C
  • No seasons - hot and wet all year round
  • High humidity, usually over 75-80%
  • Soils are latosols, not very fertile due to leaching and rapid nutrient uptake by plants
• Tropical rainforests contain the highest biodiversity of plants and animals on Earth
• One 10km2 area can contain up to 1,500 flowering plants, 750 species of trees, 400 species of birds and 150 species of butterflies
• Traditional communities in tropical rainforests

  Live in harmony with the rainforest, survive through hunting and gathering using the rainforest plants and animals in a sustainable way
• Many traditional communities have been forced off the land by commercial activities such as mining, agriculture and logging
• Interdependence in the tropical rainforest

  A change in one part affects others, e.g. deforestation leads to loss of habitats, reduction in biodiversity, and impacts the nutrient cycle
• Tropical rainforest nutrient cycle

  1. Rapid decomposition and recycling of nutrients due to high moisture and temperatures

  2. Plants grow quickly, leading to rapid uptake of nutrients from the soil

  3. Most nutrients are stored in the biomass, few in the soil and litter
• The result of the rapid nutrient cycle is that the soil in the tropical rainforest is not very fertile
• Layers of the tropical rainforest

  • Ground layer (0m)
  • Shrub layer (3-4m)
  • Under canopy (15m)
  • Canopy (30m)
  • Emergents (45-55m)
• Adaptations of plants in the tropical rainforest

  • Waxy leaves with drip tips
  • Buttress roots
  • Lianas
  • Epiphytes
  • Straight, smooth trunks
• Adaptations of animals in the tropical rainforest

  • Sloth
  • Toucan
  • Primates
  • Geckos
  • Stick insects
• Tropical rainforests have some of the highest levels of biodiversity of any ecosystem
• Threats to tropical rainforest biodiversity

  • Agriculture, particularly large scale 'slash and burn'
  • Mining
  • Hydroelectric power
  • Logging
  • Road building and settlements
  • Wildfires (increasing frequency and severity linked to climate change)
• Decline in one species (especially a keystone species)

  Can lead to a decline in other species
• Plant and animal species may become extinct, including important medicinal plants, before they are even discovered
• Indigenous communities may be forced to abandon their traditional lifestyle due to the lack of food to hunt and gather