rainforests

• Tropical rainforest ecosystems have a range of distinctive characteristics
• 2/3 of the world's plant species and % of the world's animal species are found in tropical rainforests
• Why is rainforest biodiversity so high?

  • Rainfall and temperatures are high all year round which encourages rapid growth of a large number of plants
  • Rainforests are located in tropical regions, so they receive a lot of sunlight, which is converted to energy by photosynthesis, so there are many plants
  • The canopy structure of the rainforest provides many places for plants to grow and animals to live
  • The rainforest nutrient cycling is rapid in hot, damp conditions on the forest floor, so there is rapid decay of dead plant material and plentiful nutrients easily absorbed by plant roots
• Buttress roots

  • Large wide roots on the sides of a shallow-rooted tree
  • Support the growth of large tress-create stability
  • Shallow roots to absorb nutrients from the thin surface layer
• Drip-tips


  • A pointed tip at the end of a leaf
  • Allows the high levels of rainfall to run off the leaves easily without damaging or breaking them
• Epiphytes


  • Plants that grow on other plants/trees for support and obtain nutrients from water and air rather than soil
  • Benefit from nutrients from other sources than the nutrient-poor soil
  • Grow quicker and can reach sunlight more easily
• Lianas


  • Climbing vines which climb up and twist around the tree trunks
  • Allows them to reach the sunlight faster
  • Coil around trees to avoid breaking when stretched quickly
• Both human and physical factors can influence biodiversity in tropical rainforests, e.g., deforestation, fires, lightning strikes, etc.
• There are several issues with the decline of rainforest biodiversity:
• physical characteristics of rainforests.


  • Located around the equator between the Tropics
  • Constant high temperatures between 26 and 28°C
  • High annual precipitation of over 2000mm
• why is it so hot in tropical rainforests?

  • located at the equator
  • Due to the curvature of the earth, the sun’s rays cover a smaller surface area meaning they are more concentrated making it hotter.
• Why is it so wet in tropical rainforests?

  • rising air at the equator creates low air pressure
  • which cools, condenses+ forms big clouds --> ↑ of rain
• tropical rainforest nutrients cycle

  • soil - lacks nutrients bc of the ↑ n.o plants rapidly taking it up
  • biomass - largest store of nutrients bc of the ↑ n.o animals + plants
  • litter - small + small lasting store of nutrients bc high temp and precipitation
• nutrient cycle -litter - why is the nutrients supply so small

  1. surface run off + leaching
  2. high temp + precipitation, good conditions for decomposition
• nutrient cycle - soil


  bc of the ↑ n.o plants rapidly taking up the nutrients
• nutrient cycle -biomass - large store


  bc of the ↑ n.o plants + animals