Rainforest

• Characteristics of Tropical Rainforests

  • High and constant temperatures
  • High amount of average rainfall
  • Vegetation sustains constant growth
• Tropical Rainforest Plants


  • Evergreen - do not shed all leaves at particular times
  • Continuously grow new leaves to replace older ones
  • Maintain constantly green appearance
• Tropical Rainforest Plants


  • Intense competition for sunlight
  • Grow as tall as possible to maximise exposure to sunlight for photosynthesis
• Tropical rainforests contain a very large variety of plant species, more than any other types of ecosystem in the world
• Tropical Rainforest Structure


  • Distinct vertical structure
  • Comprising 3 main layers: emergent, canopy, undergrowth
  • Not all plants can grow to the same height
• Emergent Layer


  • Uppermost layer
  • Some trees rise and tower above other trees
  • Can grow up to 30m-50m
  • Trees have tall, straight and smooth trunks with few branches
• Canopy Layer


  • Trees grow to heights of 20-30m to reach for sunlight
  • Trees grow close together (dense)
  • Crowns interlock to form an almost continuous cover
  • Blocks up to 90% of the sun's rays from reaching the forest floor
• Undergrowth Layer


  • Dark because sun's rays blocked by the canopy
  • Plants are small, thin and widely-spaced due to lack of sunlight
  • Consists of plants such as moss, ferns, some lianas and epiphytes
  • Have much larger leaves compared to other layers
  • Thin layer of leaf litter due to rapid decomposition
• Tropical Rainforest Leaves


  • Many have a drip tip to enable raindrops to run off quickly
  • Broad, waxy and leather surface
  • Capture maximum amount of sunlight for photosynthesis
  • Minimise loss of water vapour during transpiration
• Tropical Rainforest Roots


  • Buttress roots - massive ridges near the base that can rise 30 feet high
  • Provide extra stability to the tree
  • Roots are shallow as nutrients and water are found on the forest floor surface
• Tropical Rainforest Trunks


  • Tall, straight trunks with branches spread out
  • Help trees obtain maximum amount of sunlight for photosynthesis
• Tropical Rainforest Fruit and Flowers

  • Colourful and strong smelling
  • Wind-like structures to disperse seeds
  • Attract insects and other animals for seed dispersal and pollination
• Emergent layer


  Uppermost layer where trees rise and tower above other trees, can grow up to 30 to 50m, trees have tall, straight and smooth trunks with few branches
• Canopy layer


  Trees can grow to heights of 20 to 30 m to reach for sunlight, densest layer as the trees grow very close to one another, crowns of the trees interlock to form a continuous cover thus blocking out up to 90% of the sunlight
• Undergrowth layer


  Dark as sunlight is blocked by the canopy layer, plants are small, thin and widely-spaced due to lack of sunlight, moss, ferns and some lianas can be found here, plants have larger leaves to absorb as much sunlight, thin layer of leaf litter due to rapid decomposition
• Layer A is the Emergent layer
• Layer B is the Canopy layer
• The emergent layer is formed by the crowns of these trees
• The canopy layer competes for sunlight and is about 20-30m