The Amazon Rainforest, Case study

Where is it located?
70% in Brazil, but also extending into parts of Peru, Ecuador, Venezuela, Colombia, Bolivia and Guyana
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How large is it?
more than 6 million km2
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What are the average annual temperatures?
between 25-30 degrees
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What is the average rainfall?
>2000mm with no dry season
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How much of precipitation is recycled by evapotranspiration?
between 50-60%
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How much interception occurs?
accounts for 10% of precipitation
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How much of evaporation does interception account for?
20-25%
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Why are rates of evapotranspiration so high?
Due to high temperatures, abundant moisture and dense vegetation.
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Biomass
The total quantity of living/organic matter in a given area or ecosystem
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Net Primary Productivity (NPP)
The amount of carbon uptake after subtracting Plant Respiration (RES) from Gross Primary Productivity (GPP)
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Gross Primary Productivity (GPP)
The total rate at which the ecosystem capture and store carbon as plant biomass for a given length of time
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What is the Amazon's NPP
2500g/m2/year (very high)
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What is the total biomass?
between 400 and 700 tonnes/ha
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How much carbon is stored in large forest trees?
around 180 tonnes above ground and a further 40 tonnes in their roots
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How much carbon is stored in soil?
On average 90-200 tonnes/ha
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What percentage of global soil carbon is this?
27%
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How much carbon does the Amazon store per year in total?
2.4 billion tonnes
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What percentage of carbon are rainforests thought to contain in their terrestrial (land) biomass?
between 40 and 50%
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When forests are cleared and burned, how much carbon is lost to the atmosphere?
30-60%
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Why is decomposition fast?
Due to the warm humid conditions?
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How much deforestation has taken place between 1970 and 2013?
around 17,500km2/year
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What effect has this had?
reduced water storage in biomass and the atmosphere and few trees mean less evapotranspiration and therefore less precipitation.
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What happened in April 2014 due to increased run-off speeds?
There were floods in the Medeira River
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What levels did rivers reach at Porto Velho?
19.68m above normal
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What human effects did this cause?
60 people died, 68,000 families were evacuated and there were outbreaks of cholera and leptospirosis
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How much is run-off increased when rainforest is converted to grassland?
by a factor of 27 - half of all rain falling on grassland goes directly into rivers
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Why is this?
Amazonian soils contain from 4-9kg of carbon in the upper 50cm of soil whereas pasturelands contain only about a kg per m2
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How is climate change altered?
Deforestation breaks the natural cycle which sustains high atmospheric humidity which is responsible for cloud formation and heavy convectional rainfall
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Why is mining carried out?
To obtain resources like gold, copper and diamonds
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What effects can mining cause?
Mercury can get into the water system which is toxic and can harm animals. Large-scale mining operations often result in deforestation due to forest clearing and the construction of roads which reduce water flows.
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What can roads cause?
Increased surface run-off due to the impermeable surface which can increase flooding.
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What is shifting cultivation or 'slash and burn'?
A traditional method of agriculture practiced by indigenous tribes where a small area of land is cleared and burned, providing nutrients from the ash which they use for crops. When the fertility is exhausted, the tribe move onto another area.
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What effect can this have?
The soil gets washed away due to roots not anchoring the soil meaning it reaches rivers and can lead to flooding.
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What happens when forests are cut down?
Less water goes into the atmosphere and rainfall declines, sometimes leading to droughts. It also removes nutrients from the ecosystem due to nutrients not being taken up through tree roots.
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How much of the rainforest is Brazil committed to restoring by 2030?
120,000km2
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What is agro-forestry?
Growing crops and trees at the same time, so there is shelter from the canopy of trees and tree roots prevent soil erosion. The crops also benefit from the nutrients from the dead organic matter.
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What is selective logging?
Where trees are only felled when they reach a particular height - allowing young trees a guaranteed life span and the forest will regain full maturity after around 30-50 years.
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What is afforestation?
Replacing the trees that are cut down to maintain the canopy
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What are forest reserves?
Areas protected from exploitation
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What is diversification?
Where soil fertility is maintained by rotational cropping and where livestock and crops are combined to slow rates of deforestation.
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Other cards in this set

Card 2

Front

How large is it?

Back

more than 6 million km2

Card 3

Front

What are the average annual temperatures?

Back

Preview of the front of card 3

Card 4

Front

What is the average rainfall?

Back

Preview of the front of card 4

Card 5

Front

How much of precipitation is recycled by evapotranspiration?

Back

Preview of the front of card 5
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