WCC: Tropical Rainforest Case Study - Amazon Rainforest Flashcards
Case study of a tropical rainforest setting to illustrate and analyse the key themes in water and carbon cycles and their relationship to environmental change and human activity.
What is leaching?
Where rainwater washes nutrients out of the soil
How does exposed soil impact the Amazon?
Exposed soil is at risk of erosion, limiting the changes of regrowth
Describe the global distribution of tropical rainforests.
Found in a band between the tropics, covering parts of South America, central Africa and SE Asia.
What percentage of global photosynthesis do tropical rainforests acoount for?
30-50%
What percentage of the world’s oxygen emissions are tropical rainforests accountable for?
28%
What is the annual rainfall in tropical rainforests?
Over 2000mm
What are temperatures like in tropical rainforests?
27C throughout the year
Give evidence of the high biodiversity of tropical rainforests.
They are home to about 50% of the world’s species of plants and animals.
What 2 atmospheric factors lead to high precipitation in tropical rainforests?
Low pressure
High humidity
What percentage of rainfall is intercepted in tropical rainforests?
75%
Why is interception so high in tropical rainforests?
They have a dense forest canopy
What percentage of available rainwater in tropical rainforests infiltrates into the soil?
50%
What percentage of available rainwater in tropical rainforests is used by plants and returned to the atmosphere by evapotranspiration?
50%
Give evidence to show why tropical rainforest trees are critical to the regions water supply.
The Amazon Basin produces around 1/3 of its own precipitation in the recycling of evapotranspiration
What has been the main cause of deforestation in the Amazon Basin in the last 50 years?
Cattle ranching (80%)
Where is deforestation most prominent in the Amazon Basin?
The east and southeast areas in Brazil
The northwestern arc of Colombia and Ecuador
What is the largest human threat to the water cycle of tropical rainforests?
Deforestation
What percentage of its primary rainforest has the Amazon Basin lost in the past 50 years?
17%
Give evidence to show how deforestation can impact the tropical rainforest water cycle on a regional scale.
Future extensive deforestation could lead to 20% declines in regional rainfall
How much carbon does the Amazon rainforest absorb in an average year?
2.2 billion tons of CO2
How much carbon does the Amazon rainforest emit in an average year?
1.9 billion tons of CO2
What percentage of carbon in the terrestrial biomass are stored in rainforests?
40-50%
How much carbon per square metre do Amazonian rainforests store?
14-40kg
What percentage of global soil carbon is stored in rainforest soils?
27%
Contrast the difference between soil stores in pasturelands and the forests of the Amazon
Amazonian soils contain 4-9kg of carbon in the upper 50 cm of the soil layer, while pasturelands contain only about 1 kg per m^2
Contrast the difference between soil stores in pasturelands and the forests of the Amazon
Amazonian soils contain 4-9kg of carbon in the upper 50 cm of the soil layer, while pasturelands contain only about 1 kg per m^2
What percentage of carbon is lost to the atmosphere when forests are cleared and burned?
30-60%
How quickly has the size of the Brazilian Amazon rainforest been decreasing since 2000?
At an average rate of 0.3% per year
Why does the Amazon Basin no longer represent a continental carbon sink?
The amount of CO2 the Amazon rainforest absorbs from the atmosphere has declined to 1 billion tons per year. This is less that the total CO2 emitted by Latin American countries annually.
Why has carbon fertilisation of the Amazon not regulated the rise in CO2 emissions?
While rainforest plants are growing faster, they are dying sooner
