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© Oxford University Press 2009
The Disappearing CanopyThe Causes
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What human activities cause tropical deforestation?
What human activities cause tropical deforestation?
Agriculture
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Commercial logging
Mining
Dam construction
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What human activities cause deforestation in tropical rainforests?
Agriculture
Commercial logging
Mining
Dam construction
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Population growth
What are the underlying causes of tropical deforestation?
Population Resources demandedPopulation increases Resources demanded ( decrease / increase )
People demand for more food, timber,
minerals, etc.
Tropical rainforests provide land and
resources for people.
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What are the underlying causes of tropical deforestation?
As long as child mortality remains high, people will
continue to have large families.
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.
Why is population growth high in rainforested countries?
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What are the underlying causes of tropical deforestation?
Poverty
Many tropical countries have a low level of economic development.
The people are poor and receive little education.
Levels of technology and productivity is low.
Governments of poor countries do not have enough capital for economic development.
These countries are usually heavily in debt.
People picking up waste in a landfill in Cambodia(Credit: Ng Kim Hung)
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Government policy
What are the underlying causes of tropical deforestation? Provide subsidies to
commercial farmers
Encourage migration of people to the rainforests
Improve road network to increase accessibility
Corruption
Local governments are attracted by loans given by international
loan agencies for financing projects in exploiting rainforests
Loose land tenure laws enabling
developers to buy land in the rainforest
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AgricultureA Shifting cultivationShifting cultivation is mostly practised by native peoples and landless or poor peasants.
Shifting cultivators grow different crops, such as maize, beans, yams, bananas and pineapples. Some grow tree crops such as cocoa and coffee.
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AgricultureA Shifting cultivation
(Credit: Mark Edwards/Still Pictures)
The cultivators clear the site by cutting and burning the trees
The cleared plot is cultivated for several years until the soil nutrients are used up
The cultivators abandon the existing plot and move to a new plot of land
(Credit: Yann Arthus-Bertrand/Corbis)
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AgricultureA Shifting cultivation
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
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The carrying capacity of the land in tropical rainforest is low. Therefore, shifting cultivation is considered a sustainable practice.
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AgricultureA Shifting cultivation
Why has shifting cultivation become destructive to the
tropical rainforest?
Why has shifting cultivation become destructive to the
tropical rainforest?
Rapid growth in population
Growing more crops on the same amount of land
More landless peasants becoming shifting cultivators in the
rainforest also cause more destruction to the
rainforest
Soil fertility declines
The cultivation cycle is shortened
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AgricultureA 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)
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AgricultureA 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 …
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AgricultureB 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.)
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AgricultureB Plantations
Location
Rubber / oil palm plantation: West Malaysia
Coffee plantation: Brazil
Cocoa plantation: West Africa & Caribbean areas
Banana plantation: Caribbean areas
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AgricultureB Plantations
Major characteristics of plantations:
carried out by large corporationsmonoculture (single crop cultivation)Commercial, export- orientedlarge farm size
cash crop growing
Soybean plantation in Brazil
(Credit: Fernando Bueno/Getty Images)
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Soybean plantation in Brazil
(Credit: Fernando Bueno/Getty Images)
AgricultureB Plantations
Economic development results in a large demand for tropical cash crops.
This accelerates the destruction of the tropical rainforest.
In recent years, more soybeans have been grown in the rainforest to satisfy the
increasing demand for biofuel.
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AgricultureB 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
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AgricultureC Cattle ranching
Tropical rainforests are cleared to provide pastureland for cattle ranching.
Major characteristics of cattle ranching in tropical rainforests:
commercial extensive
large farm size
mainly for export Cattle ranching in Brazil(Credit: Mark Edwards/Still Pictures)
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AgricultureC 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
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AgricultureC Cattle ranching
Demand for beef increases
Overgrazing occurs
Cattle ranchers move on new sites and cut trees for
creating pastureland
Soil is exposed to erosion
Soil quality deteriorates
Deforestationspreads fast
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AgricultureC Cattle ranching – the case of Brazil
Why is the Amazon
rainforest so popular for cattle
ranching?
Why is the Amazon
rainforest so popular for cattle
ranching?
In Brazil, cattle ranching accounted for 60% of forest loss from 2000 to 2005
Cheap and extensive land supply
Poor awareness of environmental conservation
Supported by local governments
Expansion of road network, i.e. Trans-Amazonian Highway
Attractive price of Brazilian beef
Brazilian beef being free of livestock diseases
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Commercial loggingMost 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.
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Location
Central & Western Africa
ThailandIndonesiaThe 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.
Commercial logging
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Commercial logging
Logging in the rainforest is destructive since ...
Logging in the rainforest is destructive since ...
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.
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Improved logging and
transport technologiesIncreased environmental
awareness of the more
developed countries
Poor forest
managementIllegal logging activities
Rate of logging accelerates in tropical rainforests because of:
Rate of logging accelerates in tropical rainforests because of:
Commercial logging
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Mining and oil and gas exploitationMany 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)
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Hydroelectric power (HEP) is generated in rainforested countries to provide energy with plentiful water supply.
The Itaipu Dam in the Amazon rainforest
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?
Dam construction
(Credit: Reuters/OTHK)