Download Case study 8 - Winterhill School

Case Study 8
A case study of one ecosystem: processes, benefits for people, impact of human activity and
management.
Name: The Amazon Rainforest, Northern Brazil, South America
Features / Links between Ecosystem and Climate:
- In equatorial regions the temperature is constantly above 25°c so plants can
grow all year and grow quickly.
- There is plenty of water, sunshine and nutrients so there is a large variety of
plants. This means that there is also a wide variety of animals, insects and
birds.
- There is plenty of sunlight overhead so plants and trees grow straight and tall.
Processes / Links to Climate / Benefits of the Rainforest Structure:
Nutrient Cycles:
- Organic matter and minerals in rocks are
essential to keep an ecosystem healthy.
- They are broken down and the nutrients
returned to the soil to be used again by
plants.
- The speed at which the nutrients and
matter are recycled is dependent on climate.
Summary - The winter months are warm and
sunny so plants are able to photosynthesise
all through the year.
Bacteria in the soil reproduce very quickly in
the hot weather so decomposition of dead
plant matter is very rapid. This means
nutrients are transferred from the leaf litter into the soil very quickly. The chemical reactions that release nutrients from
rocks into the soil are rapid because of the heat. This process is known as weathering. If trees are cut down, heavy rainfall
can wash nutrients out of the soil. This process is known as leaching.
Water Regulation in the Rainforest
- Interception allows water to sit on leaves and then return to the atmosphere
- Water that makes its way to the floor does so via drip flow and stem flow =
slow and gentle
- Water eventually gets into the soil and is taken up by the trees etc to be
stored and returned to the atmosphere
- Eventually 80% of the water returns to the atmosphere to form clouds and
provide the water for future storms
Other benefits of the rainforest structure:
- The canopy cover protects the soil from soil erosion
Water that does not evaporate is used for:
- 200 million+ people live in rainforests and rely on the water
- Many millions more live downstream by rivers that leave the rainforests and
need that water for survival
What would be the effect on the water cycle if trees were cleared?
Water cycle would be broken so there would be disruption to the amount of evapotranspiration. This would reduce the amount of rain
and water in the atmosphere and would alter the water supply in the whole region. The water supply for millions would be at risk so
there would be people at risk of drought, flooding and starvation as crops were failed or ruined. This would also affect people further
away from the forest who rely on the water supply in the river as they would have less water. The water supply would be altered and
become uneven so there would be greater chance of flood and drought and the associated affects for people in the area.
Benefits for People: Rainforests have benefits for people globally and locally.
Task: Fill in the table to explain the so what for each of these rainforest benefits:
They maintain a steady supply
of clean water to rivers so…
They prevent soil erosion so…
They reduce the risk of river
floods so…
They provide natural materials
such as timber for building
so…
They are a natural source of
many medicines and potential
future cures for diseases so…
The rainforest provides
foodstuffs to the diet of millions
so…
Because of the trees in the
tropical rainforest, 80% of the
water returns to the
atmosphere by evaporation
and transpiration so…
At least 200million people live
in the world’s tropical
rainforests including
indigenous groups and tribes
so…
Millions more people live
downstream of rivers that leave
the rainforests and rely on the
trees to provide a constant and
even supply of water so…
Rainforests prevent soil
erosion which can lead to the
silting of rivers and flooding
elsewhere so…
Rainforests provide a vast
proportion of the world’s O2
supply so…
The rainforests are home to the
biggest variety of plants and
animals on the planet so…
Rainforest trees absorb and
store large volumes of CO2
which will help to reduce the
future impacts of global
warming and climate change
so…
Human Activity In the Amazon Rainforest:
- Cattle ranching – large areas of the forest are cleared so that herds of cattle (cows) can be reared to be sold for meat
- Mining for minerals eg gold – trees are cleared for access to valuable minerals underground which can be sold
- New roads are built – built to provide access through the forest and to allow goods to be brought in and out
- Logging for commercial reasons – cutting down valuable trees (eg mahogany) to be sold overseas
- Small scale farming – land cleared to grow crops or trees used for fuel and building
- Hydroelectric power stations – rivers dammed which floods large areas of forest and allows for electricity to be
generated
- Settlements – new places for people to live are needed as Brazil’s population is growing rapidly
- Palm Oil Production – large areas of forest cleared to grow palm oil for fuel
Why is this happening?
- Brazil has a growing population so needs to provide resources, homes and jobs. The amazon development can provide all
of these (Space for homes, industries for jobs and farming for food)
- Brazil is a LEDC / NIC which needs to develop its economy and provide better services for its population (eg schools,
health care, roads, clean water – this all needs money). Developing the rainforest generates much needed income for the
country to do these things
Impact for People and the Environment when the Amazon is Cleared:
The forest floor is open to sunlight instead of being dark
so…
The forest here has been clear felled which means…
The entire rainforest structure has been destroyed so…
Small areas of forest remaining are now isolated so…
Soil that is bare is prone to greater rates of erosion (20
times faster than natural rates) so…
…plants cannot survive and soil dries out.
…bare soil is open to the effects of the climate and erosion
as the soil is baked dry and exposed to heavy tropical
rains.
…it cannot recover and regenerate. The rainforest is lost
forever.
…they become unsustainable and die out as well.
…soil is washed into rivers where it is deposited. Silted up
rivers like this are more likely to flood and cause problems
downstream.
Consequences of Deforestation:
Summary
Water cycle and climate patterns will be altered – possible drought
Loss of habitats for animals and indigenous populations
Loss of many valuable plant species
Loss of resources so Brazil will not have any way to make money in the future
Nutrient cycles will be disrupted and the soil will become infertile
Food chains will be disrupted and animal species lost
- On a global scale, the deforestation accelerates
climate change as there is more CO2 released
when the forest is burned and less trees to
absorb what is in the atmosphere and convert it
to O2.
- This affects people all over the world due to
climate change / global warming / rising sea
levels / increased storms
Management and Sustainability (local examples):
- Brazil needs to exploit the Amazon's resources to develop, so leaving it untouched is not an option.
- Uncontrolled and unchecked exploitation can cause irreversible damage such as loss of biodiversity, soil erosion, flooding
and climate change. So, sustainable use of the forest is essential.
- Sustainable development will meet the needs of Brazil’s population without compromising the needs of future generations.
Possible strategies include:
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- Agro-forestry - growing trees and crops at the same time. This lets farmers take advantage of shelter from the canopy of
trees. It prevents soil erosion and the crops benefit from the nutrients from the dead organic matter.
- Selective logging - trees are only felled when they reach a particular height. This allows young trees a guaranteed life
span and the forest will regain full maturity after around 30-50 years.
- Education - ensuring those involved in exploitation and management of the forest understand the consequences behind
their actions.
- Afforestation - the opposite of deforestation. If trees are cut down, they are replaced to maintain the canopy.
Forest reserves - areas protected from exploitation.
- Monitoring - use of satellite technology and photography to check that any activities taking place are legal and follow
guidelines for sustainability.
- Sustainable Tourism – allowing local tribes to develop tourist lodges that are in keeping wit the forest and which benefit
them as well as making money for larger firms.
International Cooperation:
To reduce the deforestation Non-Governmental Organisations (NGOs) and foreign governments need to work with Brazil to
encourage them not to deforest further and give incentives to keep the Amazon intact.
They need to be able to develop without removing the forest as if they destroy it completely they will have no way to make
money in the future as the resource will be lost.