How does deforestation impact people and the environment?

Recap Causes of deforestation

Agricultural activities

Cattle ranching

Logging

Mining

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2

3

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Tropical Rainforest• What are tropical rainforests and where are they found?• What are the uses of tropical rainforest?• What is deforestation?• Why does deforestation occur?• How does deforestation impact people and the

environment?• How should we manage deforestation?

Lesson Objective

• Describe the impact of deforestation on people and the environment.

Impacts of deforestation


Environmental- Loss of biodiversity

- Loss of water catchment areas

- Increased risk of flooding, soil erosion and sedimentation

- Enhanced greenhouse effect

Economic- Depletion of

natural resources

Social- Effects on

indigenous people

Pair Activity

Environmental Impact Economic Impact Social Impact

Loss of biodiversity

Loss of water catchment

Increased risk of flooding

with soil erosion and

sedimentation

Depletion of natural

resources

Effect on indigenous

people

2 pairs 3 pairs 3 pairs 3 pairs 3 pairs

In pairs fill up the worksheet as follow:• State the type of impact • State the name of factor • Describe the impact of deforestation on people and

the environment

① Enhanced greenhouse effect• The earth’s atmosphere keeps the earth warm enough

for us to live.

• When the sun’s rays pass through the atmosphere and strike the surface of the earth, part of the heat is absorbed by the earth.

• The rest of the heat is reflected back into the atmosphere, towards space.

• As heat passes through the atmosphere, greenhouse gases (e.g. carbon dioxide, methane, water vapour and some other gases) in the atmosphere trap some of the heat and prevent it from escaping into space.

• This causes the warming of the atmosphere and is known as the greenhouse effect.

① Enhanced greenhouse effect

• Without the greenhouse effect, the earth’s average temperature will be −18°C rather than the current 15°C.

• However, the amount of greenhouse gases in the atmosphere has increased because of human activities.

• This has led to a rise in the earth’s average temperature as more heat is trapped in the atmosphere Enhanced greenhouse effect


• Deforestation is one of the human activities contributing to the enhanced greenhouse effect.

• Deforestation increases the amount of carbon dioxide in the atmosphere.

• Scientists estimate that about 4.8 billion tonnes of carbon dioxide are absorbed by tropical rainforests every year where the Amazon rainforest is the biggest store of carbon.


Deforestation of tropical rainforest contributes significantly to the total amount of carbon dioxide released into the atmosphere


• The enhanced greenhouse effect affects people and the environment.

For example:


Increased temperatures can cause ice caps to melt.

Results in a rise in sea levels

and flooding of low-lying

coastal areas.

Low-lying islands (Kiribati and Vanuatu in

the Pacific Ocean) may be submerged and disappear into

the sea.

As such, people living

on these islands may lose their homes.

Pair Activity

Environmental Impact Economic Impact Social Impact

Loss of biodiversity

Loss of water catchment

Increased risk of flooding

with soil erosion and

sedimentation

Depletion of natural

resources

Effect on indigenous

people

2 pairs 3 pairs 3 pairs 3 pairs 3 pairs

In pairs fill up the worksheet as follow:• State the type of impact • State the name of factor • Describe the impact of deforestation on people and

the environment

Homework

Fill up the worksheets according to the factors given to you.

Due: Tomorrow 31st March (Tuesday)

Will select 1 pair from each factor to present.








natural resources

Social- Effects on

indigenous people

② LOSS OF BIODIVERSITY

② Loss of Biodiversity • Deforestation destroys the habitats of plants and

animals.

• Loss of biodiversity = Loss of the variety of plants and animals.

• Millions of plant and animal species have become extinct.

• As a result, there is lesser variety of resources that we can obtain from the rainforest.

Plants of medicinal value are lost when a single tree is cut down in a tropical rainforest.

Imagine the loss when thousands of trees are cut down every day!

② Loss of Biodiversity

Pg 98

• Changes in biodiversity may increase the likelihood of insect-borne diseases (e.g. malaria, dengue fever) due to the lack of predators to control the population.

• The rainforest may grow back (but often not) after being deforested and if it does, the lack of nutrients in the soils may not be able to support the biodiversity that once existed on that land.

② Loss of Biodiversity

③ LOSS OF WATER CATCHMENT AREAS

• Forests play an important role in maintaining our water supply.

• They enable water to be collected and stored within a water catchment area.• The Amazon Basin is said to produce half of its rainfall

through the forest’s transpiration process in the water cycle.

③ Loss of water catchment areas

The Amazon Basin has

7,000 tributaries

Countries surrounding the Amazon rainforest depend on water from the Amazon Basin, especially during dry seasons.


• Mass clearing of trees disrupts the water cycle.

• When trees are removed, a drier climate and drier soils might occur as the ground no longer contains and receives as much water.

• In turn, this results in decreased water supply and higher water prices.• In Tanzania, deforestation caused by charcoal

production is predicted to reduce ½ of its catchment area by 2020. The cost of water is expected to rise by four times!


④ INCREASED RISK OF FLOODING, SOIL EROSION

AND SEDIMENTATION

• When trees are cleared, the ground is left bare.

• Rainwater falls directly on the ground and flows over the surface more rapidly as surface runoff.

• This causes flooding in the surrounding areas.

④ Increased risk of flooding, soil erosion and sedimentation


Interception

Infiltration

• Soil erosion is the removal of the top layers of soil by rainwater, wind and destructive human activities (logging).

• When the trees are removed, land becomes exposed.

• Water washes the soil away when it rains.


The Great Red Island in Madagascar has lost so much soil to erosion (400 tonnes for every 0.01 km2) that its rivers are blood-red, affecting even the surrounding Indian Ocean.


• Eroded soil is often washed into rivers, increasing the amount of sediments in the rivers.

• This affects water quality and aquatic life.

• The increased amount of sediments smothers fish eggs, resulting in lower hatch rates.

• Also, it turns water cloudy and prevents sunlight from penetrating the water.


Sediments enter the sea

Coral reefs get suffocated

Sediments will eventually settle and accumulate









natural resources

Social- Effects on

indigenous people

⑤ DEPLETION OF NATURAL RESOURCES

• Natural resource: Anything from the natural environment that people can use to satisfy their needs such as food, shelter, clothing, air and water.

• Tropical rainforests provide important natural resources (timber, food and water) that contribute greatly to the economic growth of many countries.

• Rapid deforestation often destroys the rainforest faster than it can replenish itself.

⑤ Depletion of natural resources

Earnings of industries that

rely on rainforest

resources get affected

e.g. timber trade.

⑤ Depletion of natural resources

⑥ EFFECTS ON INDIGENOUS PEOPLE

The Guarani community is living in makeshift camps

because parts of the forest were cleared

for sugarcane plantations,

displacing these people from their

homes in the tropical rainforest.

⑥ Effects on indigenous people

• Cutting down rainforests to create land for plantations or mining affects the lives of indigenous people.

• They lose their homes and are forced to adapt to a new way of living to survive.

• Traditionally, they live in harmony and obtain everything they need (food, shelter) from the forest.

• This displacement often causes indigenous tribes to disperse and cultures to disappear.


The impact of deforestation can be devastating. However, people have different views towards this issue


Palm oil production in Sarawak, Malaysia

• Malaysia is the world’s second largest producer of palm oil.• Currently, 40,000 km2 of the land in Peninsular Malaysia

are planted with oil palms.• New plantations have sprouted in Sarawak as land is

used up in Peninsular Malaysia.• In 2010, Sarawak was predicted to become Malaysia’s

largest palm oil producer by the end of this decade.


Summary







natural resources

Social- Effects on

indigenous people

Homework:

Workbook: • Activity 3.3: Page 41-42• Activity 3.4: Pages 43-45• Activity 3.6: Page 51

How does deforestation impact people and the environment?

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