Amazon Rainforest case study

• What is the size of the Amazon Rainforest?

  6 million km²
• What are the average annual temperatures in the Amazon Rainforest?

  Between 25-30 degrees Celsius
• What is the average annual rainfall in the Amazon Rainforest?

  Greater than 2000 mm
• Does the Amazon Rainforest have a dry season?

  No, it has no dry season
• What percentage of precipitation is recycled by evapotranspiration in the Amazon Rainforest?

  50-60%
• How is precipitation distributed throughout the year in the Amazon Rainforest?

  Evenly distributed throughout the year
• What type of rainfall is common in the Amazon Rainforest?

  High intensity convectional rainfall
• What percentage of precipitation is intercepted by forest trees in the Amazon Rainforest?

  10%
• What is the relationship between intercepted rainfall and total precipitation in the Amazon Rainforest?

  Intercepted rainfall is 25% of all precipitation
• Why are there high rates of evapotranspiration in the Amazon Rainforest?


  Due to high temperatures, abundant moisture, and dense vegetation
• What proportion of incoming rainfall is returned to the atmosphere through evapotranspiration in the Amazon Rainforest?


  Half of the incoming rainfall
• From where does most evapotranspiration occur in the Amazon Rainforest?


  From intercepted moisture on leaf surfaces
• Amazon Rainforest - Water cycle

  • Rapid run-off related to high rainfall, intensive rainfall events and well drained soils; river discharge peaks in 1-2 months of year
  • High temps allow atmosphere to store large amounts of moisture; relative and absolute humidity is high.
  • Abundant rainfall and deep tropical soils leads to significant water storage in soils and aquifers.
  • Trees absorb and store water from soil and release it through transpiration
• What is the average Net Primary Productivity (NPP) of the Amazon rainforest?


  2500 g/m²/year
• What is the biomass range of the Amazon rainforest?


  400-700 tonnes/ha
• How much carbon do large forest trees store per hectare in the Amazon rainforest?


  220 tonnes C/ha
• How much carbon does soil store per hectare in the Amazon rainforest?


  90-200 tonnes of Carbon/ha
• How much carbon does the Amazon rainforest absorb per year?

  2.4 billion tonnes of Carbon
• Why are exchanges of carbon between the atmosphere, biosphere, and soil rapid in the Amazon rainforest?

  High temperatures facilitate rapid exchanges
• What conditions in the Amazon rainforest ensure fast decomposition of dead organic matter?

  Warm, humid conditions
• What is the significance of the Amazon's leached and acidic soils?

  They contain limited carbon and nutrient stores
• What does the Amazon rainforest's high NPP and biomass indicate about organic matter processing?

  • Emphasizes the speed at which organic matter is broken down
  • Highlights rapid mineralization and recycling of nutrients
• What is the relationship between the Amazon rainforest's conditions and its carbon cycle?

  Warm and humid conditions promote rapid decomposition and carbon exchange
• How does temperature affect the water cycle?

  • High temps = high rates of evapotranspiration
  • Convection is strong = high atmospheric humidity = development of thunder storms, clouds and intense precipitation.
• How does rock permeability and porosity affect the water cycle?

  • Impermeable catchments have minimal water storage capacity resulting in rapid run-off
  • Permeable porous rocks like limestone and sandstone store rainwater and slow run-off
• How does relief affect the water cycle?

  • Areas of gentle relief - water moves across surface or horizontally through soil to streams and rivers.
  • Widespread inundation across extensive floodplains occurs annually, storing water for several months and slowing movement into river
• How does temperature affect the carbon cycle?

  • High temps + humid conditions promote rapid decomp of organic litter by bacteria and fungi
• How does rock permeability and porosity affect the carbon cycle?

  • Amazon Basin (Igneous + Metamorphic rocks) = carbonates largely absent
  • Western parts of basin = outcrops of limestone occur, a significant regional carbon store in slow carbon cycle
• How does vegetation and organic matter affect the carbon cycle?

  • High temps + humid conditions promote rapid decomp of organic litter
  • Decomp releases nutrients to soil for immediate take up by tree root systems and emits CO2 into atmosphere
• How much deforestation is happening in Amazonia?


  It averaged at 17/500km^2/year between 1970-2013
• What were the effects of the Madeira River basin floods in April 2014?

  • Port Velho - River reached record levels of 19.68m above normal
  • 60 people died
  • 68,000 families evacuated
  • Outbreaks of cholera and leptospirosis
• What were the effects of deforestation in the Upper Madeira basin?

  • Reduced water storage in forest trees, soils, plant roots and atmosphere
  • Less precipitation due to fewer trees
  • Total run-off speeds increased, raising risk floods throughout basin
• What was the main driver of the floods?

  Deforestation in Peru and Bolivia
• How much of the Bolivian rainforest was cleared?

  • 30,000km2 cleared for subsistence farming and cattle ranching from 2000-2013
  • Happened mostly on lower slopes of Andes = massive reduction in water storage and rapid run-off
• How does converting rainforest to grassland affect the water cycle?

  • Increases run-off by a factor of 27
  • 1/2 of all rain falling on grassland directly falls into rivers
• What will happen if deforestation continues in Amazonia?

  • Prediction of 20% decline in regional rainfall as forest dries out and forest trees replaced by grassland.
  • Disruption of regional water cycle = forests hundreds of kilometres downwind of degraded sites also affected.
• What does the biomass of trees represent?


  60% of all carbon in the ecosystem
• What is one impact of deforestation on carbon cycle?


  It exhausts the carbon biomass store
• What is the biomass of grasslands and soya cultivation in areas of former rainforest?

  • Biomass of grasslands = 16.2 tonnes/ha
  • Biomass of soya cultivation = 2.7 tonnes/ha
• How does deforestation affect the soil?


  It reduces inputs of organic matter to soil as it's depleted of carbon and exposed to sunlight = supports fewer organisms = reduced flow of carbon to atmosphere