Tropical rainforests are found between 10 degrees north and south of the equator, mainly in the Amazon Basin, Congo Basin, and parts of Southeast Asia. They have 5 layers - emergent, canopy, understory, shrub, and undergrowth. Tropical rainforests are adapted to high heat and rainfall through features like broad, evergreen leaves and buttress roots, and adaptations like waxy leaves that shed water easily and shallow roots that spread widely to absorb nutrients. Common plant types include epiphytes that grow on trees, lianas that use trees to reach sunlight, and parasitic plants that compete with host trees.

1. Tropical Rainforest
OBJECTIVES
• Describe and explain distribution
of tropical rainforest.
• Describe the features of tropical
rainforests.
• Describe how tropical rainforest
adapt to the environment.

2. Overview
ADAPTATIONS
PLANTS
STRUCTURE
DISTRIBUTION
TROPICAL
RAINFOREST

3. RAINFOREST
DISTRIBUTION

4. Location of tropical rainforests

5. Location of tropical rainforests

6. DISTRIBUTION
• Found in places between 10°N and 10°S of the
Equator
• Mainly located in Amazon Basin, Congo Basin,
and parts of Southeast Asia such as Malaysia
and Indonesia.

7. DISTRIBUTION

8. DISTRIBUTION
• Why?: high temperatures (27°C) and high
rainfall (above 1500mm) throughout the year.
• This promotes abundant plant growth which is
typical of tropical rainforests.

9. RAINFOREST
STRUCTURE

11. STRUCTURE
• 5 distinct layers: Emergent, Canopy,
Understorey, Shrub, Undergrowth
• [You are expected to label/ describe every
layer in detail]

12. STRUCTURE
• Emergent:
– 30-50m
– Tall trees (Emergent trees)
– Tall, thick, straight trunks
• Canopy
– 15-30m
– Wide, umbrella shaped crowns
– Continuous leaf cover called canopy

13. STRUCTURE
• Understorey
– 6-15m
– Narrower, oval-shaped crowns (?)
– Young trees of canopy, emergent
• Shrub
– 5m
– Tree saplings, woody plants

14. STRUCTURE
• Undergrowth
– 0-5m
– Grasses, ferns, mosses, fungi
– Sparse growth (?)

15. RAINFOREST
CHARACTERISTICS
PAGE 40-43

16. RAINFOREST
FEATURES

17. #1: Sparse Undergrowth
• There is sparse undergrowth in the forest floor
of the tropical rainforest.
• This is because very little sunlight (about one
percent) passes through the canopy and
reaches the forest floor.

18. #2: Large Variety
• There is a large variety of plants in the tropical
rainforest. It is estimated that rainforests may
contain more than 750 species of trees and
1500 species of other plants.
• This is because of consistent high temperature
and rainfall throughout the year that promotes
plant growth.

19. #3: Extreme density
• Tropical rainforests are extremely dense due to
the presence of a large variety of plant species
which can grow in the tropical rainforest.

20. #4: Evergreen Leaves
• Tropical rainforests have evergreen leaves due
to the consistently high rainfall throughout the
year.

21. #5: Large & broad
leaves
• Tropical rainforests have large and broad
leaves to maximise the surface area for
photosynthesis.

22. #6: Thin & smooth barks
• Tropical rainforests have developed thin and
smooth barks because there is no need for
protection against cold or dry conditions.

23. #7: Buttress Roots
• Some trees in the tropical rainforest have
buttress roots, which are thick and spread out
widely to support the great weight of trees.

24. RAINFOREST
ADAPTATIONS

25. #1: Low Light
• The canopy layer prevents sunlight from
reaching the lower layers of the tropical
rainforests.
• Some plants such as the epiphytes and lianas
have adapted to this low light condition by
growing on tree branches.
• Furthermore, these trees have branches
only on the top one-third portion of the
trunks to get maximum sunlight.

26. #2: Bacteria Growth
• High temperature and high rainfall in the
tropical regions promote rapid growth of
bacteria.
• Hence, tropical rainforest have waxy leaves
with drip tips to allow rainwater to drain off
easily.
• This prevents harmful bacteria from growing
and protects the plants from diseases.

27. #3: Still air below canopy
• The presence of the continuous canopy results
in still air in the layers below it and this does not
allow pollination to be carried out by wind.
• Hence, flowers and fruits in the tropical
rainforest are colourful and sweet-
smelling.
• This attracts insects for pollination and animals
for seed dispersal.

28. #4: Rapid humus formation
• High temperatures and rainfall all year round
causes the leaf litter to decompose and form
humus rapidly.
• This supplies nutrients to the topsoil, which is
the uppermost layer of the soil.
• Hence, the roots of trees in the tropical
rainforest are shallow and spread widely
to absorb the nutrients present in the topsoil.

29. RAINFOREST
PLANTS

30. EPIPHYTES
• This refers to plants that grown on and use
trees for physical support.
• Rainwater and decaying leaves provide the
epiphytes with water and nutrients.
• Example: Bird’s Nest Fern, Orchids

31. LIANAS
• Refers to thick, woody vines that wind around
tree trunks to reach for sunlight

32. PARASITIC PLANTS
• This refers to plants that compete with the host
tree for space, sunlight and nutrients.
• These plants are common in the canopy and
understorey layer of the rainforest.
• Example: Strangling Fig

33. Summary
ADAPTATIONS
PLANTS
STRUCTURE
DISTRIBUTION
TROPICAL
RAINFOREST