Earth’s Life Support Systems
OCR AS/A Level Geography Example Case Studies
Table of Contents
Tropical Rainforest ..................................................................................................... 2
Amazon Basin ............................................................................................................................................ 2
Arctic Tundra ............................................................................................................. 4
1
,Amazon Basin
BACKGROUND
Location (2) South America
Primarily Brazil, but also neighbouring countries
Area 6 million km2
Length of Amazon 6,400 km
River
Tropical rainforest 50% of all global tropical rainforest cover is found in the
cover Amazon
Global land carbon 25% of all global land carbon is stored in the Amazon
PHYSICAL FACTORS VEGETATION
Tree density (2) 400-600 stems/ha
Forests in western Amazonia have on average 150 more
stems/ha than in eastern Amazonia
Impact on water 25% of evaporation is from the surface of leaves
cycle (3) 10% of rainfall is intercepted by vegetation
Dense vegetation = rapid rates of transpiration
Impact on carbon Vegetation stores 100bn tonnes of carbon
cycle (4) Absorbs 2.4bn tonnes of CO2 per year
60% of rainforest carbon stored in above ground biomass
>50% of carbon is used up in respiration by plants
CLIMATE & TEMPERATURE
Average temperature 26-27oC all year round
Average rainfall 2000mm/year
Impact on water High annual temperatures drive transpiration
cycle (2) Hot climate allows air to store large amounts of
atmospheric moisture (high absolute humidity)
Impact on carbon High annual temperatures stimulate primary production
cycle (3) NPP averages about 2500g/m2/year
Rapid decomposition, releasing CO2 into atmosphere
GEOLOGY
Underlying geology Igneous Brazilian Shield
(2) Some sedimentary rock in the central belt
2
, Impact on water Impermeable and low porosity of underlying geology
cycle means infiltration and percolation is difficult
Impact on carbon Lack of carbonate geology, therefore limited impact
cycle
MADEIRA
DRAINAGE BASIN
Background (2) Drainage basin in southwestern Amazon
Area of deforestation
Precipitation Rainfall 100% above normal
[Natural factor]
Deforestation 30,000 km2 of land was cleared for subsistence
[Human factor] agriculture and cattle ranching between 2000 and 2012
2014 Madeira Basin Water levels reached 19m above normal
Flood Event (3) 22,000 homes evacuated in the area
60 deaths
Impact on water Converting forest to grassland increased surface run-off
cycle (4) by 27x
Cattle ranching compacts soil, reducing infiltration
50% of all falling rain goes directly into rivers
20% decline in regional rainfall
HUMAN ACTIVITY
% of rainforest lost to 20% (since 1970)
deforestation
Logging Clear cut felling, selecting felling
Urbanisation Brazil currently building 7,500km of highways across the
Amazon
Agriculture Pasture and arable farming, and palm oil plantations
Mining Mining for copper, tin and nickel
Impact on water Positive feedback loop- removal of trees reduces rainfall,
cycle so less vegetation is able to grow
Impact on carbon Soils become depleted of nutrients
cycle (3) Decrease in carbon taken from atmosphere by plants
Farming stores less carbon than forest- soya cultivation
stores 2.7tonnes/ha, grasslands store 16.2tonnes/ha
MANAGEMENT
STRATEGIES
Protection through Includes laws and schemes to protect what’s left
legislation (2) 44% of rainforest protected and banned from farming
Parica Project Developed 1,000km2 commercial timber plantation of 20
(Afforestation) (3) million hardwood seedling
Would take 25 years to mature
Cannot replicate biodiversity of forest- monoculture
Improving Increasing crop diversity improves soil quality so less
agricultural land has to be deforested in the future
techniques (2) ‘Dark soils’ made from charcoal, waste and human
manure attract micro-organisms, helping soil to retain
fertility
3
OCR AS/A Level Geography Example Case Studies
Table of Contents
Tropical Rainforest ..................................................................................................... 2
Amazon Basin ............................................................................................................................................ 2
Arctic Tundra ............................................................................................................. 4
1
,Amazon Basin
BACKGROUND
Location (2) South America
Primarily Brazil, but also neighbouring countries
Area 6 million km2
Length of Amazon 6,400 km
River
Tropical rainforest 50% of all global tropical rainforest cover is found in the
cover Amazon
Global land carbon 25% of all global land carbon is stored in the Amazon
PHYSICAL FACTORS VEGETATION
Tree density (2) 400-600 stems/ha
Forests in western Amazonia have on average 150 more
stems/ha than in eastern Amazonia
Impact on water 25% of evaporation is from the surface of leaves
cycle (3) 10% of rainfall is intercepted by vegetation
Dense vegetation = rapid rates of transpiration
Impact on carbon Vegetation stores 100bn tonnes of carbon
cycle (4) Absorbs 2.4bn tonnes of CO2 per year
60% of rainforest carbon stored in above ground biomass
>50% of carbon is used up in respiration by plants
CLIMATE & TEMPERATURE
Average temperature 26-27oC all year round
Average rainfall 2000mm/year
Impact on water High annual temperatures drive transpiration
cycle (2) Hot climate allows air to store large amounts of
atmospheric moisture (high absolute humidity)
Impact on carbon High annual temperatures stimulate primary production
cycle (3) NPP averages about 2500g/m2/year
Rapid decomposition, releasing CO2 into atmosphere
GEOLOGY
Underlying geology Igneous Brazilian Shield
(2) Some sedimentary rock in the central belt
2
, Impact on water Impermeable and low porosity of underlying geology
cycle means infiltration and percolation is difficult
Impact on carbon Lack of carbonate geology, therefore limited impact
cycle
MADEIRA
DRAINAGE BASIN
Background (2) Drainage basin in southwestern Amazon
Area of deforestation
Precipitation Rainfall 100% above normal
[Natural factor]
Deforestation 30,000 km2 of land was cleared for subsistence
[Human factor] agriculture and cattle ranching between 2000 and 2012
2014 Madeira Basin Water levels reached 19m above normal
Flood Event (3) 22,000 homes evacuated in the area
60 deaths
Impact on water Converting forest to grassland increased surface run-off
cycle (4) by 27x
Cattle ranching compacts soil, reducing infiltration
50% of all falling rain goes directly into rivers
20% decline in regional rainfall
HUMAN ACTIVITY
% of rainforest lost to 20% (since 1970)
deforestation
Logging Clear cut felling, selecting felling
Urbanisation Brazil currently building 7,500km of highways across the
Amazon
Agriculture Pasture and arable farming, and palm oil plantations
Mining Mining for copper, tin and nickel
Impact on water Positive feedback loop- removal of trees reduces rainfall,
cycle so less vegetation is able to grow
Impact on carbon Soils become depleted of nutrients
cycle (3) Decrease in carbon taken from atmosphere by plants
Farming stores less carbon than forest- soya cultivation
stores 2.7tonnes/ha, grasslands store 16.2tonnes/ha
MANAGEMENT
STRATEGIES
Protection through Includes laws and schemes to protect what’s left
legislation (2) 44% of rainforest protected and banned from farming
Parica Project Developed 1,000km2 commercial timber plantation of 20
(Afforestation) (3) million hardwood seedling
Would take 25 years to mature
Cannot replicate biodiversity of forest- monoculture
Improving Increasing crop diversity improves soil quality so less
agricultural land has to be deforested in the future
techniques (2) ‘Dark soils’ made from charcoal, waste and human
manure attract micro-organisms, helping soil to retain
fertility
3
