1.17. Amazon Rainforest Case Study Flashcards
Why does the atmosphere become less humid?
Evapotranspiration is reduced because there is less photosynthesis so less water is released and less carbon is absorbed and more is left in the atmosphere.
Less clouds and condensation so area becomes drier.
What will happen to rates of interception, evaporation and evapotranspiration?
Decreased interception as there are few trees so most rainfall will reach the ground immediately.
Little evaporation of leaves -> transpiration virtually 0
Evaporation increases as temps increase.
What happens to overland flow and soil compaction/ saturation?
Soils are becoming saturated as less interception so increases runoff so increases flood risk.
What happens to the rate of runoff?
Rates of runoff will increase with an increased risk of flooding
Soil is saturated
What happens when the soil becomes drier?
Becomes like an impermeable surface so soil starts to crack and infiltration rates decrease.
Water will evaporate or runoff.
If soil particles are dry and can move easily, causing soil erosion.
How does slash and burn impact the carbon cycle in the Tropical Rainforest?
Cutting down trees reduces the amount of carbon absorbed from the atmosphere and burning them releases carbon into the atmosphere.
When they’re burned, nutrients are released and more plants grow which absorb carbon -> negative feedback
How much of Brazil’s greenhouse gas emissions are attributed to deforestation and land use changes?
75%
59% of this is from forest loss and burning in the Amazon
What do slash and burn techniques do?
- Reduces retention of humidity in soil’s top layer
- Reduces porosity of soil, causing faster rainfall drainage, erosion and silting of rivers and lakes
- Loss of emitting of salts and organic fibres along with water when they transpire so inhibits formation of cloud and reduces rainfall.
- Carbon released into atmosphere
What is the average temp in the rainforest?
24.1 degrees celsius
How much carbon is the Amazon estimated to store?
80-120 billion tons of carbon
How much has forests been increasing in above ground biomass?
0.3-0.5% per year and that the rising productivity of tropical forests is due to sequestering of increased Co2 concentrations in the atmosphere.
Counterargument of increased above ground biomass
- A 2015 study revealed that the Amazon forest is losing its capacity to absorb Co2 from the atmosphere
- From a peak of 2 billion tons of Co2 each year in the 1990s, net uptake by the forest has halved and now has been overtaken by fossil fuel emissions in Latin America.
- There has been a growth spurt for the Amazon’s trees; however the growth causes trees to live faster and so die younger, leading to a surge of trees dying across the Amazon
What is the net loss in the Amazon Basin?
3.6 million hectares per year between 2000 and 2010
Most has been caused by deforestation but some due to climate change - climate change can affect species as they may have an intolerance to temp change, drought and seasonality
What has also played a role in the Amazon in recent years in killing millions of trees?
Droughts and unusually high temperatures
What would a 2 degree celsius temperature rise above pre-industrial levels see?
20-40% of the Amazon die off within 100 years
What would a rise of 3 degrees Celsius see?
75% of forest destroyed by drought over the following century with a 4 degree celsius rise killing 85%
What may warming water temps lead to?
- Kill off temp dependent species
- Change biodiversity of river systems by introducing new species and killing others
- Reduce water dissolved oxygen concentrations which could destroy eggs and larvae, which rely on oxygen for survival
How much of the Amazon covers South America?
40%
How many species is the Amazon home to?
- 1million plant species
- 500 species of mammals
- 2000 species of fish
How much rain does the Amazon have every year?
2300mm
