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The Disappearing Canopy. The Causes. Agriculture. What human activities cause tropical deforestation?. Commercial logging. Dam construction. Mining. What human activities cause deforestatio n in tropical rainforests?. Agriculture. Commercial logging. Mining. Dam construction.

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Presentation Transcript
slide2

Agriculture

What human activities cause tropical deforestation?

slide3

Commercial logging

Dam construction

Mining

slide4

What human activities cause deforestation in tropical rainforests?

Agriculture

Commercial logging

Mining

Dam construction

slide5

Population growth

What are the underlying causes of tropical deforestation?

Tropical rainforests provide land and resources for people.

People demand for more food, timber, minerals, etc.

Population increases

Population

Resources demanded ( decrease / increase )

Resources demanded

slide6

What are the underlying causes of tropical deforestation?

Why is population growth high in rainforested countries?

This is no official family planning in Brazil because of the influence of the Roman Catholic Church.

Among Malays, Chinese and Indians lived in Malaysia, Malays tend to have more children in the family. Their ideal family size is to have more than four children.

As long as child mortality remains high, people will continue to have large families.

slide7

Poverty

People picking up waste in a landfill in Cambodia

(Credit: Ng Kim Hung)

What are the underlying causes of tropical deforestation?

Many tropical countries have a low level of economic development.

The people are poor and receive little education.

Governments of poor countries do not have enough capital for economic development.

Levels of technology and productivity is low.

These countries are usually heavily in debt.

slide8

Government policy

What are the underlying causes of tropical deforestation?

Provide subsidies to commercial farmers

Encourage migration of people to the rainforests

Loose land tenure laws enabling developers to buy land in the rainforest

Improve road network to increase accessibility

Local governments are attracted by loans given by international loan agencies for financing projects in exploiting rainforests

Corruption

slide10

Agriculture

A Shifting cultivation

Shifting cultivation is mostly practised by native peoples and landless or poor peasants.

Shifting cultivatorsgrow different crops, such as maize, beans, yams, bananas and pineapples. Some grow tree crops such as cocoa and coffee.

slide11

(Credit: Mark Edwards/Still Pictures)

Agriculture

The cultivators clear the site by cutting and burning the trees

A Shifting cultivation

The cultivators abandon the existing plot and move to a new plot of land

(Credit: Yann Arthus-Bertrand/Corbis)

The cleared plot is cultivated for several years until the soil nutrients are used up

slide12

Agriculture

A Shifting cultivation

The carrying capacity of the land in tropical rainforest is low. Therefore, shifting cultivation is considered a sustainable practice.

Major characteristics of shifting cultivation:

Subsistence, mainly for own consumption

small farm size

labour intensive

staple crop growing

Footage showing shifting cultivation in western Africa

Please click to browse online

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Agriculture

A Shifting cultivation

Rapid growth in population

Growing more crops on the same amount of land

Why has shifting cultivation become destructive to the tropical rainforest?

More landless peasants becoming shifting cultivators in the rainforest also cause more destruction to the rainforest

Soil fertility declines

The cultivation cycle is shortened

slide14

Agriculture

A Shifting cultivation

  • The pros:
  • It may be a suitable way to make use of the harsh environment in the TRF, with the low level of technology.
  • The labour productivity is relatively high.
  • The energy output (harvest) is high when
  • compared with the energy input.
  • i.e. a high energy ratio
  • It causes little environmental damage, providing
  • that the fallow period is long enough (e.g. 20 yrs)
slide15

Agriculture

A Shifting cultivation

  • The cons:
  • It increases loss of nutrients by burning of biomass, leaching of bases and increased soil erosion.
  • It degrades the primary forest (the climatic climax) to secondary forest, resulted in lower density, lower height, smaller biomass, lower species diversity and more open structure.
  • It can only support a very small population size, or the exceeding population pressure may cause long term ecological damages.
  • * Viscous cycle of soil depletion: poor harvest
  • frequent movement shorter cultivation cycle
  • shortened fallow period lower soil fertility …
slide16

Agriculture

B Plantations

Tropical rainforests are felled for growing cash crops:

Tree crop: rubber, oil palm, cocoa and coffee

Arable crop: sugar cane and soybean

Coffee plantation in Brazil

(Credit: Biosphoto/Gunther Michel/Peter Arnold Inc.)

slide17

Agriculture

B Plantations

Location

Rubber / oil palm plantation: West Malaysia

Coffee plantation: Brazil

Cocoa plantation: West Africa & Caribbean areas

Banana plantation: Caribbean areas

slide18

Agriculture

B Plantations

Major characteristics of plantations:

carried out by large corporations

monoculture (single crop cultivation)

(Credit: Fernando Bueno/Getty Images)

Commercial, export-

oriented

large farm size

cash crop growing

Soybean plantation in Brazil

slide19

Agriculture

B Plantations

Economic development results in a large demand for tropical cash crops.

This accelerates the destruction of the tropical rainforest.

(Credit: Fernando Bueno/Getty Images)

In recent years, more soybeans have been grown in the rainforest to satisfy the increasing demand for biofuel.

Soybean plantation in Brazil

slide20

Agriculture

B Plantations

Reasons for destruction of the tropical rainforest:

  • Deliberate introduction & cultivation of economically
  • desired species of tropical / subtropical plants
  • Causing widespread replacement of the native &
  • natural flora (and fauna), modifications or
  • disturbance of the natural landscape.
  • Artificial practices
  • e.g. permanent removal of natural vegetation,
  • improvement of drainage and soil,
  • application of chemicals
slide21

Agriculture

C Cattle ranching

Tropical rainforests are cleared to provide pastureland for cattle ranching.

Major characteristics of cattle ranching in tropical rainforests:

commercialextensive

large farm size

mainly for export

Cattle ranching in Brazil

(Credit: Mark Edwards/Still Pictures)

slide22

Agriculture

C Cattle ranching

Location

Central America: at least 2/3 of the arable land is used for cattle production

  • Amazon Basin: about 1/5 had been cleared for farming and cattle ranching
  • * Brazil:
  • the world’s largest exporter of beef since 2004
  • - cattle ranching accounted for 60% of forest loss
  • from 2000 to 2005
slide23

Agriculture

C Cattle ranching

Deforestation

spreads fast

Demand for beef increases

Cattle ranchers move on new sites and cut trees for creating pastureland

Overgrazing occurs

Soil is exposed to erosion

Soil quality deteriorates

slide24

Agriculture

C Cattle ranching – the case of Brazil

Why is the Amazon rainforest so popular for cattle ranching?

Cheap and extensive land supply

Attractive price of Brazilian beef

Poor awareness of environmental conservation

Supported by local governments

Brazilian beef being free of livestock diseases

In Brazil, cattle ranching accounted for 60% of forest loss from 2000to 2005

Expansion of road network, i.e. Trans-Amazonian Highway

slide25

Commercial logging

Most trees in the tropical rainforests are hardwoods. They are quality raw materials for construction purposes and for making furniture, e.g. Teak, Mahogany, Brazilian Rosewood.

slide26

Commercial logging

Location

Central & Western Africa

  • Thailand
  • Indonesia
  • The Amazon Basin, etc.
  • * They export large amount of tropical timbers, sawn
  • wood and plywood to the developed countries.
  • The US & UK have been the main importers of
  • Mahogany.
  • The vulnerable Brazilian Rosewood has been harvested as a highly prized wood for decorative veneers, high-quality furniture (e.g. musical instruments), resin & oil.
slide27

Logging activities are often unchecked / greenwashed.

Clear-cutting is carried out. Tools: elephants vs bulldozers, caterpillar wheels, crane?

Trees are cut to provide space and to build roads.

The roads built by the logging companies provide access for other forest users.

Commercial logging

Logging in the rainforest is destructive since ...

slide28

Commercial logging

Rate of logging accelerates in tropical rainforests because of:

Improved logging and transport technologies

Increased environmental awareness of the moredeveloped countries

Illegal logging activities

Poor forest management

slide29

Mining and oil and gas exploitation

Many rainforests are rich in mineral reserves, e.g. bauxite, coal, tin, and oil and gas deposits, by open-cast, strip and shaft mining methods.

Urucu oil and natural gas plant in the Amazon

Gold mining in the Amazon

(Credit: Reuters/OTHK)

(Credit: Reuters/OTHK)

slide30

Dam construction

Hydroelectric power (HEP) is generated in rainforested countries to provide energy with plentiful water supply.

HEP is considered the most reliable source of energy in the rainforested countries because:

it rains every day in the tropical rainforests;

high annual rainfall;

water never freezes.

How about the problems?

The Itaipu Dam in the Amazon rainforest

(Credit: Reuters/OTHK)