2a - Amazon rainforest CS Flashcards
Where is the Amazon rainforest + what part do we study
South America - 70% in brazil
Madeira river basin
Average temp in Amazon rainforest
25-30•C
- there is very little seasonal variation 2•
Average rainfall - Amazon
High average annual rainfall
>2000mm + no dry season
Why is there high precipitation
High rates of evapo-Transpiration due to high temp + dense vegetation
How much carbon does the rainforest absorb a year
2.4 million tonnes
How does the geology of the Amazon rainforest affect flows of water
Mostly impermeable rock = very little percolation + high surface run off + through flow (water through soil)
West in Andes there is permeable rock
How does the temperature as a physical factor affect the flows of water - Amazon rainforest
High temp = high evapo-transpiration
High amount of convection rainfall
- very little diurnal change (less than 9•c difference) so water continuously cycled
What is the effect of the little change in average temps around year
12 month growing season = vegetation photosynthesising year round
- vegetation also regularly drop leaves + branches building a litter layer on Forrest floor = decomposition
2 key physical factors affecting carbon stores + flows
Vegetation + temperature
How could deforestation affect water cycle
Fewer trees = decreased evapotranspiration + less precipitation as result
- Run off increase due to less interception + less infiltration into soil
= increase chance of flood
How could urbanisation affect water stores + flows
Increase in run off = impermeable surfaces
- less infiltration
- less transpiration + interception
The changing demand for water increases or decreases aquifer stores due to extraction
How does fossil fuel use affect carbon stores + flows
Decrease in sedimentary rock store = combustion + atmospheric store increases
- more carbon in air = more diffusion into oceans (high conc to low) = however warmer climate due to greenhouse effect = oceans release carbon
Do warmer oceans increase carbon absorption?
As oceans get warmer they hold less CO2
Colder oceans can absorb more
How does agriculture affect carbon store and flows
Compared to previous land in rainforest their is much less biodiversity + photosynthesis = decrease biomass
- less leaf litter = less decomposition + soil store
Why can trees not grow back after deforestation
Soil does not contain nutrients required = soil erosion + nutrients washed away by bleaching
Name 3 management strategies at the tropical rainforest
Protected areas
Afforestation + replanting
Improved agricultural techniques
Why might afforestation not work
Trees take a while to grow
Trees do not have nutrients required in soils
How much of Brazils rainforest is protected
44%
Protected as part of Amazon Regional Protected areas scheme
- protected by government where deforestation is forbidden = no disruption to natural cycles
Give one example of a improved agricultural technique
Rotational cropping
- growing different plants to maintain mix of nutrients in soil = able to use same area for longer
- reduces need for slash + burn for new areas
How have hydroelectric projects affected carbon + water cycles
- dams block river = increase in surface storage behind dam = short term reduction in stores downstream
- can cause flooding reducing transpiration + photosynthesis
- biomass may decompose anaerobically = produces methane
- the impacts of HEP are limited due to scale + number- 140 in total
NPP of Amazon
8800
Measure of biomass
Aim of parcia project in amozaon rainforest
Develop 1000km2 commercial timber plantation
Planting 20 million fast growing seedlings
= this will not bring back biodiversity but will significantly sequest carbon
why are improved agricultural techniques a limited management strategy in Amazon
difficult to persuade farmers to try new method
what percentage decline in regional rainfall is expected in The Amazon rainforest due to Deforestation
20% decline
How many tonnes of carbon are released into the atmosphere via decomposition in Amazon Rainforest
1.8 Billion tonnes
Percentage of deforestation for cattle farming
60%
how many hydroelectric projects are in Amazon basin
140
Impact therefore limited by number
how many Hectares of land cut down in Amazon 2021
2 million
