Amazon Flashcards
(31 cards)
What is the total annual rainfall in the Amazon?
Over 2000mm (rises to 6000mm in some NW regions)
This high precipitation input is crucial for the Amazon’s ecosystems.
What proportion of the total input of precipitation leaves the Amazon Basin as river discharge into the Atlantic?
Approximately 1/3 discharges into the Atlantic
This is below average for a river.
What happens to the rest of the precipitation that does not discharge into the Atlantic?
Most of the remaining 2/3s leaves the system via evapotranspiration and can fall again as precipitation.
What is the average temperature in the Amazon?
27°C all year round (no seasons)
This consistent temperature influences water processes.
How does the structure of the tropical rainforest affect water transfers/processes?
The almost continuous canopy intercepts up to half of precipitation.
Some water evaporates from leaves, while the rest reaches the ground as throughfall or stem flow.
What is the biggest cause of deforestation in the Amazon?
Agriculture - commercial crops e.g., soy and palm oil and cattle ranching.
How much of the Amazon Forest has already been lost?
17% over the last 50 years (close to 1/5)
This significant loss impacts biodiversity and water cycles.
What proportion of the Amazon Forest will be treeless by 2030 if current rates of deforestation continue?
More than ¼ according to the WWF.
How does deforestation or conversion of forest to crops affect water stores and transfers?
Vegetation storage reduces, leading to increased river discharge locally due to fewer trees to absorb water.
What local effects can occur next to cleared forest areas?
There is evidence of an increase in rainfall.
How does burning felled timber for agriculture affect rainfall?
Burning can reduce rainfall due to lower evapotranspiration.
What are the consequences of reduced vegetation on local water cycles?
Lower rainfall locally and regionally due to less evapotranspiration, resulting in smaller clouds and less precipitation.
What is the potential reduction in regional rainfall according to studies?
Studies suggest that regional rainfall could reduce by up to 20%.
What notable change occurred in Rondônia regarding the rainy season?
Data shows an 18-day delay in the rainy season compared to the 1970s.
What happens to air over a cleared area compared to air over forest?
Air over a cleared area warms faster, creating localized low pressure as warmer air rises.
What role do ultrafine airborne aerosols play in precipitation?
They cause water to condense around them, but the droplets formed are too small and light to fall as rain.
What proportion of all carbon in the biosphere is stored in the Amazon?
1/5 or 20%.
How much carbon does the Amazon Rainforest absorb in a normal year?
2 billion tonnes
What proportion of global photosynthesis do rainforests account for?
30-50%
What % of soil carbon is found in the top 30cm of the soil?
52% (over half)
What proportion of anthropogenic carbon emissions come from deforestation?
10% (second cause after burning hydrocarbons)
Until the 1990s, what effect did increases in atmospheric CO2 have on carbon sequestration in the Amazon?
Increased rates of photosynthesis, transferring carbon to the biosphere
What type of feedback is the increased concentration of atmospheric carbon leading to increased photosynthesis an example of?
Negative feedback
Why can the Amazon absorb less carbon in the 21st century?
Increased carbon concentrations cause plants to die more quickly and less carbon stored in biomass
