adaptations of tropical forests

• characteristics of an equatorial climate are:

  • hot, wet climate where high temperature and high rainfall are experienced throughout the year.
  • high mean annual temperature of about 27 degrees
  • small annual temperature range of 2 degrees
  • more than 2000mm of total annual precipitation.
• structure of a tropical rainforest:

  
  

  emergent layer - made up of the tallest trees called emergents , grow 40-50m tall

  
  

  canopy layer - crowns form a continuous canopy , trees are 20-30m tall , prevent sunlight from reaching the ground , presence of non-parasitic plants

  
  

  understory layer - smaller trees with narrow crowns , trees are 5-15 meters , presence of some lianas & epiphytes

  
  

  shrub layer - mainly shrubs , ferns & small young trees

  
  

  ground layer - sparse vegetation due to lack of sunlight , saprophytes , small plants & ferns

  
• leaves

  *evergreen*

  • leaves are not shed over the same period of time
  • continuous plant growth
  • germination, flowering and fruiting takes place throughout the year

  trees do not need to shed all their leaves before a dry season because there are no distinct dry seasons in equatorial climate where there is high and regular rainfall, and little seasonal variation.
• biodiversity of tropical rainforest

  • luxuriant and dense
  • great species diversity, 300-400 species per hectare of land why? 


  the spreading branches of the closely-spaced interlocked

  equatorial climate encourages/supports rapid plant growth, the rich biodiversity is a response to the highly favorable condition of abundant rainfall and sunlight throughout the year
• leaves

  large, broad leaves 


  large broad leaves : larger surface area captures more sunlight and maximizes photosynthesis to make food, because in equatorial climate, there is sunlight all year round
• leaves

  • thick & leathery
  • smooth & waxy 


  thick and leathery: leaves are thick and leathery to withstand the heat and reduce moisture loss through evapotranspiration, because in the equatorial climate, the mean annual temperature is high, usually around 27 degrees

  smooth and waxy: these leaves allow rain water to run off them easily so that the leaf surface can be kept dry. Moist surfaces encourage mold, bacteria and fungus growth and some plant diseases may develop and result in leaf decay
• extra info :

  • The surface area to volume ratio (SA/V ratio) is a measure of how much surface area is available per unit volume of an object.
  • In biology, this ratio is crucial because it influences the efficiency of processes like nutrient absorption, waste removal, and heat exchange, which occur across the surface of cells and organisms.
• leaves

  • downward- pointing drip-tips 


  drip - tips allow excess water to run off, so that the leaf surface can be kept dry as well as to prevent damage to leaves. Moist surfaces encourage mold, bacteria and fungus growth and some plant diseases may develop and result in leaf decay. this is important as the climate experience high total annual rainfall of more than 2000mm and has high relative humidity levels.
• fruits and flowers

  • fruits - sweet-smelling
  • flowers - colourful

  colourful and sweet-smelling fruits and flowers all year round to attract insects birds and animals to aid in pollination and seed dispersal because the air is generally still (little wind to propagate seeds under the canopy) due to the dense nature of the forest
• trunk

  trees with tall, straight trunks

  signs of competition for light, air, space and nutrients ; trees grow as straight as possible to achieve maximum height and obtain maximum light
• bark

  smooth and thin bark 


  smooth bark - to allow rain water to flow down to the roots easily

  thin bark- no need to protect against cold or dry weather as there are no extreme climatic conditions
• branches

  branches & leaves found at the top one-third of trees

  more energy efficient for trees to have branches and leaves at the top to obtain maximum sunlight for photosynthesis as the layers beneath the canopy are dark and have very little sunlight
• roots

  shallow roots

  water is readily available at the surface from high rainfall and provides much moisture in the topsoil

  shallow roots maximize the absorption of nutrient found in the topsoil as the abundant rainfall and the hot, moist equatorial climatic environment encourage the rapid decomposition of leaf litter at the surface to form nutrients
• roots

  buttress roots

  larger entrees have buttress rots that can be 1 to 5 meters above the ground 


  the broader base helps to support the heavy weight of tall trees, as trees in the canopy and emergent layers are very tall
• belongs in the tropical climate zone, in the equatorial region
• soil

  • nutrient poor because nutrients are not stored in them for very long. the heavy rains that occur in rainforests wash organic material from the soil
  • many of the dead fallen leaves and other organic matter are swept away before releasing all of their nutrients.
  • nutrients released by decomposition are taken up quickly by the plants, instead of being stored in the soil (refer to roots)