Sec 1 ppt for uint 3 2014

1. DEFORESTATION AND ITS IMPACT ON
PEOPLE AND THE ENVIRONMENT
•Part III

2. YOU WILL LEARN
• How deforestation impact people and
the environment
• To understand and describe the
impact of deforestation on the
1. Environment
2. Economy
3. Social factors

3. ENVIRONMENTAL IMPACT
Loss of biodiversity
• Refers to the loss of the
variety of plants and
animals resulting in
millions of them
becoming extinct
• It has resulted in the loss
of the variety of resources
that can be obtained
from the forest. Read pg
98 for further information
Loss of water catchment
areas
• Clearing forest disrupts
the water cycle
• Trees absorb water
through their roots and
release it into the
atmosphere through
evaporation and
transpiration.
• Loss of water catchment
results in decreased
water supply

4. ENVIRONMENTAL IMPACT
Incensed risk of flooding, soil erosion and sedimentation
• Flooding
• Soil absorbs rainwater
and releases it slowly into
the rivers.
• Forest intercept the rain
and allow it to seep into
the ground
• When trees are cleared,
the ground is left bare
and rainwater flows as
surface run-off
• This causes flooding in
the surrounding areas

5. ENVIRONMENTAL IMPACT
Incensed risk of flooding, soil erosion and sedimentation
• Soil erosion
• Refers to the removal
of the top layers of soil
by rainwater, wind,
destructive human
activities
• Trees hold the ground,
the leaves and moss
keep the ground stable
• When trees are removed,
land is exposed.
Therefore water washes
the soil away when it
rains.
• Refer to TB pg 100 – the
Great Red Island in
Madagascar
• This affects water quality
which affects aquatic
life- see TB pg 101 Fig 3.44

6. ENVIRONMENTAL IMPACT
Enhanced greenhouse effect
• When the sun’s rays pass
through atmosphere, part of
the heat is absorbed by the
earth and the rest is reflected
back to the atmosphere
towards space.
• Greenhouse gases( carbon
dioxide, methane, water
vapour and other gases) trap
some of the heat and
prevent it from escaping into
space. This causes warming
of the atmosphere and is
known as greenhouse effect.
• Without greenhouse effect
the earth average
temperature will be -18°C
instead of the current 15°C.
• There is an increase in
greenhouse gases due to
increased human activities
like logging, industries,
transportation, power
stations resulting in more
heat being trapped. This is
called enhanced
greenhouse effect

7. ENHANCED GREENHOUSE EFFECT.

8. DEFORESTATION AND EMISSION OF
GREENHOUSE GAS
• Deforestation Increases
the amount of carbon
dioxide in the
atmosphere
• Trees absorb carbon
dioxide in the
atmosphere and store
as carbon and when
tress are cut the stored
carbon is released into
the atmosphere
• Burring of forest also
releases carbon dioxide
into the atmosphere
• Less trees means less
carbon dioxide is
absorbed and more
remain in the atmosphere
• Refer to TB pg 103 Fig 3.46
World map showing
contribution of greenhouse
gases emission due to
deforestation

9. ECONOMIC IMPACT
Depletion of natural resources
• Natural Resources
• Rapid deforestation
results in the depletion
of the natural resources
faster than it can
replenish.
• This affects the earning
of industries that rely on
natural resources like
timber
• Social impact
• The indigenous people
in Amazon forest face
threats of losing their
land due to loggers
• Read and try the
exercise on TB pg 105 if
to find out more ……..

10. Deforestation results in:
a. Loss of biodiversity
b. Loss of water catchment areas
c. Incensed risk of -flooding,
- soil erosion
-sedimentation
a. 4. Enhanced greenhouse effect
2 Economic impact – loss of resources
3 Social impact – affects the lives of indigenous people
1. Environmental impact

11. HOMEWORK
Workbook
• Activity 3.3
• Pg 42
Activity 3.4
Pg 43, 44, 45
• Activity 3.6
• Pg 51
Activity 3.7
Pg 53 – 56
Activity 3.8
Pg 57 – 60

12. WORLD :NOTICE THE RAINFOREST COVER &
COMPARED TO THE MAP ON PG 43