the disappearing canopy

© Oxford University Press 2009

The Disappearing CanopyThe Causes


What human activities cause tropical deforestation?

What human activities cause tropical deforestation?

Agriculture


Commercial logging

Mining

Dam construction


What human activities cause deforestation in tropical rainforests?

Agriculture

Commercial logging

Mining

Dam construction


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.



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?



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)


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


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.


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)



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.



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



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)



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 …


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.)



Location

Rubber / oil palm plantation: West Malaysia

Coffee plantation: Brazil

Cocoa plantation: West Africa & Caribbean areas

Banana plantation: Caribbean areas



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)


Soybean plantation in Brazil

(Credit: Fernando Bueno/Getty Images)


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.



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


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)



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



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


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


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.


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


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.


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


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)


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)

the disappearing canopy

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