3.1.1.5 Case Studies Flashcards
The amazon rainforest and the River Exe
Where is the Amazon rainforest?
between the tropics
the majority lies within Brazil with the remainder mainly in Peru and Columbia
How large is the Amazon rainforest?
2.1 million square miles
How much of the Earth’s surface do tropical rainforests cover?
6%
How much of global photosynthesis do rainforest account for?
30-50%
What is the avg annual rainfall in the Amazon?
2000+ mm
What is the avg daily temperature in the Amazon?
27 degrees c
How much of the world’s oxygen do rainforests emit?
28%
what is the climate like in the amazon?
high, daily precipitation as a consequence of low pressure and high humidity conditions
how much precipitation is intercepted by the canopy?
75%
How much of all available rainwater is used by plants and returned to the atmosphere by evapotranspiration?
50%
what happens to the remaining half of all available rainwater?
infiltrates into the soil
why are the trees of the forest critical to the regions water supply?
because evapotranspiration ensures water enters the atmosphere and in turn produces rain
how much rain does the Amazon basin produce through the recycling of evapotranspiration?
1/3
where does the other two thirds of precipitation come form?
in moisture laden air from the Atlantic Ocean
how much of its primary forest has the Amazon lost as a result of deforestation in the last 50 years?
17%
what is the main reason for deforestation of the amazon?
cattle ranching due to huge meat demands
how has deforestation affected evapotranspiration in the amazon? and what effects does this have?
significantly reduced
means the air is less moist resulting in reduction in cloud cover and precipitation
how has deforestation affected interception in the amazon? and what effects does this have?
very little interception now
rainfall can reach the ground immediately which compacts soils. water leaves as overland flow so less is returned to the atmosphere and there is an increase in the risk of flooding
why is more solar radiation reflected by clear land?
it has a higher albedo than forest canopy
what effects of deforestation limits the chances of regrowth?
soil erosion
how will deforestation affect regional rainfall?
decline by 20%
what are rainforests often descried as and why?
lungs of the earth
because they emit a great deal of oxygen
how much carbon does wood/trees store?
50%
how much carbon does the amazon absorb every year?
2.2 billion tonnes of carbon
how much carbon does the amazon emit every year and through what processes?
1.9 billion tonnes
decomposition and organism respiration