The Tropical Rainforest

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The Tropical Rainforest

• IB SL

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Location
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Introduction...

• They are the world's most productive ecosystems
  in terms of NPP and biomass.
• They are complex ecosystems with variations in
  climate, temperatures, and vegetation, within
  individual forests.
• Temperatures are often thought to be permanently
  high, but they are highest on the forest edge
  where vegetation is more limited.
• The climate changes on a daily basis within the
  forest, and the idea of the forest being
  difficult to penetrate is only true at the edges
  where the sunlight allows rapid growth of
  vegetation.

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Development

• Their development relies on...

Insolation And Temperatures High temps. Allow All Year Growth Of Vegetation.
Moisture Varies throughout the year, and true TRFs are said to have rainfall in excess of 2000mm and a dry season of no longer than 2 months.
Nutrients Scarce, but are rapidly recycled and transferred. Phosphorus and nitrogen are the nutrients needed most.
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Structure
Layer Characteristics
Top (Euphatic) Most productive (NPP, animal life and biomass). Tress over 25m. 25 of available energy absorbed.
Middle (Oligotrophic) Trees are 10 - 25m.
Bottom Smaller trees and some young saplings between 5 and 10m in height.
Shrub Smaller seedlings and some pygmy trees of 5 to 10m.
Herb Tree seedlings, and ferns in existence.
Top Root Roots that penetrate to a depth of 5cm (majority).
Middle root Fewer roots to a depth of 5 - 50cm.
Bottom root Minimal numbers of roots in this layer, below 50cm.
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Structure
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Climate

• Small annual temperature range (2 - 4 degrees).
• Regular insolation, result of location near
  equator.
• Daily temperature range in excess of annual range
  (8 - 10 degrees), with daytime temperatures up to
  32 degrees.
• High levels of convectional rainfall, often with
  a minimum in July/August/September.
• Extremely high humidity levels.
• Light winds.
• Quick evapotranspiration.
• Year long growing season (but not all plants in
  the forest grow all year).

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Vegetation

• Decay of leaf litter is rapid, and nutrient
  recycling.
• Photosynthesis occurs all year.
• Extremely large variety of vegetation, trees
  appear to be evergreen but are deciduous.
• Vegetation adapts to the climate. For example,
  buttress roots to support tall trees, drip tips
  to help remove excess moisture.
• Tallest trees can be over 50m high and are known
  as emergence.
• Where forests are near the coast Mangrove swamps
  may be found.

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Soils

• May appear to be fertile but the tropical
  latosols are not.
• The humus layer is extremely thin, as is the
  amount of litter.
• Leaching occurs as a result of the high
  precipitation and is increased greatly by
  deforestation.
• Minerals such as Calcium and magnesium are lost.
• Bedrock is weathered quickly.
• The characteristic red colour of the soil is due
  to iron and aluminium accumulating.

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Carbon Cycle
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Nutrient Cycle
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Activity

• Using Chapter 3 of AS Level Geography P102-103,
  answer the following questions...
• Where in the world are Tropical Rainforests
  mainly located?
• What are the main vegetation types and how have
  they adapted to the environment?
• How does the nutrient cycle work?
• What impacts do humans have on these areas?