Give an overview of the Amazon Rainforest:
Largest tropical rainforest
Covers 40% of South American landmass
Home to over 1 millon plant species, 500 mammal species, 2000 fish species
What contributes to the Amazon's wet climate?
- High evaporation over Atlantic Ocean
- Wet air blown towards Amazon
- Results in high rainfall
What are the characterisics of the water cycle in the Amazon?
- High precipitation - due to evaporation from Atlantic Ocean + warm temps
- High interception - dense canopy
Describe the role of the Amazon in the carbon cycle:
- Increasing CO2 in atmosphere
- Increasing productivity as vegetation is able to access more CO2 for photosynthesis
Why might we not be able to rely on the Amazon rainforest as an effect carbon sink in the future?
Although the trees are growing more quickly, they are dying younger.
How does deforestation affect the water cycle in the Amazon?
- Less interception
- Increased surface runoff = increased flood risk
- Reduced rate of evapotranspiration
- Less water vapour reaches atmosphere
- Fewer clouds = increased risk of drought
How does deforestation affect the carbon cycle?
- No roots to hold soil together = heavy rain washes away the nutrient-rich soil = transfers carbon to hydrosphere
- Less leaf litter = no humus = soil cannot support growth = limits carbon absorbed
- Fewer trees = more atmospheric CO2
How does climate change affect the Amazon rainforest?
- Severe droughts - in 2005 and 2010
- Plants + animals adapted to moist conditions and so die in dry climates.
- Droughts = wildfires = CO2 released
What will a 4oC temperature rise do to the Amazon according to scientist predictions?
Kill 85% of the rainforest.
What attempts have been made to limit human impacts in the Amazon rainforest?
How has selective logging reduced human impacts in the Amazon?
- Only some trees are felled
- Forest structure is kept - canopy in tact and soil is protected
- Forest can regenerate with limited impact on carbon + water cycles
How has replanting reduced human impacts on the Amazon?
- New trees are planted to replace old trees, eg. Peru restoring 3.2 million hectares of forest by 2020.
- Important to plant trees of the same type as those cut down, so variety is kept.
How environmental law reduced human impacts in the Amazon?
- Ban the use of wood from unsustainable forests
- Ban excessive logging
- Control land use, eg. Brazilian Forest Code (50-80% of land must be kept forest)
How has protection reduced human impacts on the Amazon?