Tropical Rainforests

Tropical Rainforests

1. Location

   • Between the tropics of cancer and capricorn.
     • 23.5 N and 23.5 S
   • Found in South America, Central America, Asia, Oceania, and Africa.
   • Cover about 7% of the Earth's surface.
   • Largest in the Amazon Basin

2. Climate

   • No seasons
   • Precipitation
     • Over 2000mm of rainfall per year
   • Temperature
     • Average daytime temperature of 28 C
     • The temperature never drops below 20 C
     • The temperature rarely goes above 35 C
   • Hot and humid atmosphere
   • Consistant climate all year round.

3. Structure

   • Soil
     • Not very fertile
       • All nutrients are absorbed quickly be the plantlife
       • Only a thin layer on top is fertile due to decomposing organisms
       • Nutrients washed away through leaching
     • Red in colour
       • Rich in iron
   • Shrub layer
     • Receives less than 2% of sunlight.
       • Very little grows here
       • Plants and animals adapted to living in very low light
   • Under canopy
     • Receives 2%-15% of sunlight
     • Very large and open
     • Contains young trees and leafy plants that can tolerate little light
   • Canopy
     • 60-90 feet above ground
     • Contains all the branches of the trees
       • The branches form a tight net over the other layers
       • Branches covered with epiphytes
       • Vines (lianas) also grow here
     • Home to 90% of all living organisms found in the rainforest.
   • Emergent
     • Home to giant trees that grow above the canopy layer
       • The trees have to be able to deal with the high temperatures, high winds, and low humidity
       • The trees here have the greatest amount of sunlight

4. Nutrient cycle

   • Very fast nutrient cycle
   • Most nutrients held in the biomass
   • Only a small amount of nutrients held in the litter and soil
     • Most nutrients washed out of soil through leaching
     • Trees are evergreen so they rarely lose their leaves
   • Nutrients are added to the cycle from the atmosphere into the biomass
   • Nutrients are added to the soil from the weathered rocks below
     • Nutrients are also lost into the bedrock from the soil
   • Nutrients are free to move in the cycle
     • Nutrients move from the biomass to the litter and soil as organisms die
     • Nutrients move from the litter to the soil as dead organisms decompose
     • Nutrients move from the soil and litter to the biomass as they are absorbed by the living organisms

5. Flora and fauna

   • Plant adaptations
     • Drip-tip leaves
       • Plants have leaves with pointy tips. These tips help water to run off quickly.
     • Buttress roots
       • Large roots have ridges to increase the surface area to help support the larger trees
     • Very straight trunks
       • Long, straight trunks help excess water to be removed quickly.
     • Can grow very quickly
       • Can harness any small amount of sunlight to quickly grow to get more
     • Epiphytes
       • A type of plants that have adapted to live in the branches of trees
       • They get nutrients from the air and water, not from the soil.
     • Lianas
       • A type of woody vine.
         • They have roots in the ground but have adapted to climb the trees so that their leaves and flowers can reach the sunlight.
   • Animal adaptations
     • Sloth
       • Uses camoflage
       • Moves slowly to avoid being spotted
     • Spider monkeys
       • Long, strong limbs to help it climb through trees.
     • Flying frog
       • Has fully webbed hands and feet so that it can open its feet and glide between plants.
     • Toucan
       • Has a large, long bill to allow it to reach fruit on branches that are too weak to support it's weight.

6. Uses

   • Timber
     • Hardwoods
       • Teak
       • Mahogany
       • Ebony
       • Very strong wood
       • Durable
       • Considered to have a very beautiful colour and texture
       • Used to make furniture and flooring
   • Scientific research
     • Medicine
       • Over 3000 species of plants in the rainforest have cancer fighting properties
         • Cinchona tree
           • Treats malaria
         • Clavilla plant
           • Treats eczema
           • Treats irritations and itchyness
         • Madagascar periwinkle
           • Treats childhood lukemia
       • Less than 1% of plants in the rainforest have been tested for their medical properties
     • New food sources
     • Undiscovered species
   • Land use
     • Agriculture
     • Infrastructure
       • Trans-Amazonion highway
   • Jobs
     • For local people
     • Road building
     • Logging
     • Agriculture
     • Mining
       • For gold
       • Use mercury
         • Clumps gold together but gets into water supplies
       • Open cast mining
         • Leaves behind a giant hole
         • Scars the landscape
         • Often have to remove a large area of forest before hand
     • Construction
   • Tourism

7. Management

   • Logging and replanting
     • Selective logging of mature trees
     • Ensures that the rainforest canopy is preserved
     • Allows the forest to recover
       • Younger trees now have the light and space to grow
     • Ensures that for every tree removed another is replanted
   • Education
     • Helps people to understand the importance of the rainforest
     • The more people understand about the rainforest, the more they will want to protect it
   • Ecotourism
     • Encourages sustainable tourism
     • Creates jobs for local people and creates money to help protect the rainforest.
   • International agreements
     • Debt-for-nature swaps
       • Some of the country's debt is removed as long as they use that money to protect their rainforests.
   • Harsher sanctions
     • Illegal logging and poaching is now met with harsher sanctions
       • Makes people consider the risk before taking the action

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