Tropical Rainforest Case Study- The Amazon Rainforest

• How big is the Amazon Rainforest?


  -the worlds largest tropical rainforest

  -covers 40% of the South American landmass
• What climate does the Amazon have?

  very hot and wet with dense vegetation
• Who/what lives in the Amazon Rainforest

  -indigenous people

  -around 1 million plant species

  -500+ mammal species

  -2000+ species of fish

  -Home to many endangered species (black caiman, Amazonian manatee)
• How does the water cycle cause the Amazon to be wet?

  -Water cycle causes the Amazon to be very wet

  -lots of evaporation over the atlantic ocean, the wet air is blown towards the amazon

  -contributing to Amazons very high rainfall
• Warm temperatures in the Amazon mean?...

  evaporation levels are very high, increasing the amounts of precipitation
• The rainforest has a dense canopy meaning?...


  -interception is high

  -As a result, less water flows into rivers than may be expected and it does so more slowly
• The water cycle affects the Amazons species..

  -its populated by species adapted to high humidity and frequent rainfall
• The Amazon is a carbon sink

  -The Rainforest stores lots of carbon in its vegetation and soil making it a carbon sink

  -estimated to store between 80 and 120 billion tonnes of carbon

  -Along with other tropical rainforests it forms a sink of 1-3 gigatonnes (GtC) of CO2 a year

  -Studies show above ground biomass is increasing by 0.3-0.5% each year

  -rising productivity of rainforests is due to sequestering of increased CO2 concentrations in the atmosphere
• Increasing CO2 has led to increased productivity in the Amazon. Why?

  -the vegetation can access more co2 for photosynthesis, the biomass has been increasing
• Whats happened to the amount of sequestered CO2 in the Amazon?

  -the amount of CO2 being sequestered has increased, making it an important carbon store
• Whats happening to the trees life spans?

  -trees are growing faster but dying younger. They are speeding up their life spans.

  -We may not be able to rely on the Amazon rainforest to be such an effective sink in the future
• How does deforestation affect the water cycle?

  -in deforested areas there's no tree canopy for interception, more water reaches the ground. There's too much water for the soil to soak in so runoff increases, increasing the risk of flooding

  -Deforestation reduces the rate of evapotranspiration, less water vapour reaches the atmosphere, fewer clouds form, rainfall is reduced increasing risk of drought
• How does deforestation affect the carbon cycle?

  -Without roots holding soil together, heavy rain washes away the nutrient rich top layer of soil, carbon stored in soil will be transferred to hydrosphere

  -There will be less leaf litter, humus isn't formed. Soil cannot support much new growth limiting the amount of carbon absorbed

  -Trees remove CO2 from the atmosphere and store it, fewer trees means more CO2 in the atmosphere, enhancing the greenhouse effect and global warming
• How is climate change impacting the rainforest temperatures?

  -In some areas temperature is increasing and rainfall decreasing, leading to drought

  -Amazon had severe droughts in 2005, 2010 and 2015-16
• How is climate change impacting rainforest species?

  -plants/animals living there are adapted to moist conditions, many species die in bad weather

  -frequent/long periods of drought could lead to extinction of species

  -drought can also lead to forest fires, which can destroy large areas of forest, releasing lots of CO2 into the atmosphere
• Limiting human impacts on the Amazon - selective logging


  -only some trees (eg. oldest ones) are felled - most are left standing

  -Less damaging than felling all the trees in an area. If only a few trees are taken from areas the forest structure is still kept - canopy is still there and the soil isn't exposed

  -forest is able to regenerate, impact on carbon and water cycle is low
• Limiting human impacts on the Amazon - Replanting


  -New trees planted to replace the ones cut down

  -EXAMPLE: project in Peru replanted 115+ acres of forest between 2016-19

  -Important the same type of trees are replanted as the ones cut down, so variety is kept for the future & local water and carbon cycles return to their initial status
• Limiting human impacts on the Amazon - Environmental law


  -laws that control land use ( Brazilian Forest code says landowners have to keep 50-80% of their land as forest)
• Limiting human impacts on the Amazon - Protection


  -Many countries have set up national parks/nature reserves to protect the rainforest ( Central Amazon Conservation Complex in Brazil set up in 2003 to protect biodiversity in a 49,000 Km squared are whilst allowing local people to use the forest in a sustainable way)

  -Within national parks/nature reserves damaging activities like logging can be monitored and prevented
• Carbon in Amazon affecting trees

  -2015 study shows Amazon is losing its capacity to absorb CO2 from the atmosphere

  -peak of 2 billion tonnes each year in the 1990s, net uptake by the forest has halved. For the first time its overtaken by the fossil fuel emissions in South America

  -trees have had a growth spurt. Trees life cycles are accelerated, growing faster dying younger

  - as a result the rate of tree death in the Amazon has surged in recent years.
• Amazon River


  -Average discharge of water from the river to the atlantic is approx 175,000 m3/s

  -around 15% of the fresh water entering oceans each day
• The Rio Negro tributary


  -second largest river in the world in terms of water flow, 100m deep 14 km wide near its mouth at Manaus Brazil

  -Average rainfall across the whole Amazon basin is approx 2,300 mm annually

  - some parts of the NW portion, rainfall can exceed 6,000 mm annually
• Reasons for deforestation - settlement and population growth

  -Many people are migrating to the forest looking for work associated with the natural wealth of this environment.

  -The Brazilian Amazon's population grew by a massive 23% between 2000 and 2010, 11% above the national average.
• Reasons for deforestation - mineral extraction

  -forests are also cleared to make way for huge mines.

  -The Brazilian part of the Amazon has mines that extract iron, manganese, nickel, tin, bauxite, beryllium, copper, lead, tungsten, zinc and gold!
• Reasons for deforestation - logging

  -This involves cutting down trees for sale as timber or pulp.

  -The timber is used to build homes, furniture, etc. and the pulp is used to make paper and paper products.
• Reasons for deforestation - agriculture

  -To grow crops (Soya or Palm oil) or for pasture land for cattle grazing.

  -The clearing of land for cattle ranching accounts for 80 percent of deforestation in the Amazon.
• The Amazon rainforest is the largest tropical rainforest on Earth, covering over 5 million km2.
• Amazon Rainforest absorbs around 35% of the world’s annual CO2 emissions and produces more than 20% of the world‘s oxygen