1. ✔
1. What are some types of natural vegetation?
✐
2. How are forests useful to humans?
3. What happens if we overuse forests?

2. By the end of the lesson,
You should be able to:
– List and elaborate three uses of forests.
Looks manageable? Let's start!

3. Functions/Uses of the forest
1. Maintains water supply 6.Habitat for life
2. Replenishes oxygen, b) maintains the quality
7. Provides timber, fuel,
of water supply
removes carbon dioxide medicine, food,
chemicals
3. Maintains nutrients in quantity
a) maintains the
the soil of water supply Recreation
8.
4. Prevent floods 9. Research and
education
5. Protect coasts

4. a) maintains the quantity
1. Maintaining water supply of water supply through
transpiration
2. Water vapour condenses into
tiny droplets of water in the
atmosphere and form clouds.
3. The clouds precipitate
as rain when they have
too much water to hold.

1. Forests release large
amounts of water
vapour into the
4. The rain that falls atmosphere through
replenishes the water in transpiration.
rivers and reservoirs.

5. b) maintains the quality
1. Maintaining water supply
of water supply through
i) filtering it
Soil traps and filters
impurities in rainwater
and in waste water (such
as dead animals, rubbish,
human waste) that seeps
underground before it
flows into rivers and
reservoirs.
→ This water is thus
relatively clean

6. b) maintains the quality
1. Maintaining water supply
of water supply by
i) filtering it
Biodegradable waste that
has been trapped is
decomposed by bacteria
present in the forests.
E.g. Mangrove roots filter
river water of its waste
materials before it flows into
the sea. The waste is broken
down into nutrients for the
mangroves.

7. b) maintains the quality
1. Maintaining water supply of water supply through
ii) intercepting foliage
1. The foliage of the
forest intercepts and
weakens the impact + Interception slows
of raindrops hitting the down surface runoff so
ground. less soil particles are
2. Forest soil thus 
washed into the river,
remains porous making the water
enough to let water cleaner.
seep underground.
3. This water is stored
as groundwater, which
flows to and
replenishes nearby
rivers and reservoirs.

8. Textbook p. 182
Foliage interception slows
down surface runoff.
Less soil particles get washed into the river
Rainwater seeping into the
Water that finally gets to the river soil
is cleaner. is filtered by the soil.

9. How does the water quality in
forested areas compare with
urban areas, like....
Singapore, Rio de Janeiro,
London, Shanghai,
Johannesburg, Cairo?

10. Textbook p. 182
Concrete surfaces means that
rainfall runs over the ground quickly
+
collects impurities along the way

11. 2. Replenishes O2, removes CO2
Forests: 'Green Lungs of
the Earth'
During photosynthesis,
the greenhouse gas
CO2 is absorbed,
preventing global
temperatures from rising.
O2 is released, renewing
oxygen supply for all life.

12. 3. Maintains nutrients in the soil
4. Plants absorb
1. Dead plant these nutrients in
and animal the soil.
matter
accumulate on
the forest floor.
3. Calcium, nitrates
and phosphates are
2. Decomposers released from dead
cause dead matter into the soil
matter to rot.

13. 4. Prevents floods
Forest roots hold the soil
firmly together. This:
a) keeps the soil porous as
a store for rainwater
flowing over the ground
b) prevents soil from being
eroded and deposited in
riverbeds, reducing their
capacity to contain water.

14. 5. Protects coasts
Mangroves form the first line
of defense against wave
attack and coastal hazards.
E.g. Sri Lanka, 2004 Boxing
Day tsunami -
Only 2 deaths in a village with
densely growing mangroves;
up to 6000 deaths in a nearby
village with no mangroves
(BBC News)

15. 6. Habitat for life
Forests are habitats for flora
(plants) and fauna
(animals), providing

Food

Shelter from heat or cold

Protection from predators
Matschie's tree-kangaroo, Papua
(Unfortunately, some are
New Guinea's tropical rainforests
endangered, e.g. Matschie's
tree-kangaroo and all species of
tigers)
American pika, temperate Tigers, tropical rainforests and
coniferous forests monsoon forests

16. 7. Provides valuable resources
Valuable resources include
timber for furniture and
buildings.

Teak, meranti, rattan
(tropical rainforest);
mahogany, pine, spruce
(temperate coniferous
forests)
United Nations' Food and
Agriculture Organization
(FAO) estimate that every
year, the global timber
industry earns over S$332
billion!

17. 7. Provides valuable resources
Valuable resources include
medicine.

Quinine, treatment for malaria,
from Cinchona trees (tropical
rainforest)

Tannin from mangrove
Rhizophora and redwood trees
(coniferous forests) to make anti-
diarrhea pills

18. 7. Provides valuable resources
Valuable resources include
chemicals.

Pine and fir resin as wood
varnish

Tannin from mangrove
Rhizophora and redwoods to
treat leather and make orange
food dyes

19. 8. Recreation
Forests can be used for
ecotourism.

Tourists who want to
experience nature without
harming it.
Yosemite National Park, California

These forests are
USA sometimes national parks
and wildlife reserves.
More of this when we study
deforestation in Kalimantan.
Sungei Buloh Wetland
Reserve, Singapore

20. Functions/Uses of the forest
1. Maintains water supply 6.Habitat for life
2. Replenishes oxygen, 7. Provides timber, fuel,
removes carbon dioxide medicine, food,
chemicals
3. Maintains nutrients in
the soil 8. Recreation
4. Prevent floods 9. Research and
education
5. Protect coasts

21. What's next?
We will study the final section for this topic:
What happens when humans
interact with the forest?
We'll study deforestation (the destruction of
tropical rainforests) in Kalimantan,
Indonesia. Read textbook pp. 196-201.