The Amazon Rainforest - Water & Carbon Cycle Case Study

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  • The Amazon Rainforest - Water and Carbon Case Study
    • Facts
      • Largest tropical rainforest
      • 40% South American landmass
      • Hot, wet, dense vegetation
      • Indigenous people
      • 1 Mil plant species, 500 mammal species, 2000 fish species
      • Home to endangered species: Manatee (mammal), Black caiman.  (reptile) , Pirarucu (fish)
    • Water Cycle
      • Wet air blown over Atlantic towards Amazon = wet rainforest = high rainfall
      • Warm temp = high evaporation = increases precipitation
      • Dense canopy = high interception = less flow into rivers = also more slowly
      • Species adapted to high humidity, frequent rainfall
    • Carbon Cycle
      • Carbon stores = vegetation, soil = carbon sink
      • Increased productivity because vegetation has access to more CO2 = increasing biomass
      • Increased sequestered carbon
      • Trees grow quick but die young
        • May not be able to rely on rainforest as a carbon sink in future
    • Human Activities
      • Deforestation: lots exploitation of timber or use land for farming
        • Effects on water cycle
          • No canopy to intercept rainfall = too much water in soil = surface runoff = increased risk of flooding
          • Reduces evapotranspiration  rate = fewer clouds = reduced rainfall = increased risk of drought
        • Effects on carbon cycle
          • No roots to hold soil together = rain washes away nutrient rich soil = carbon from soil transferred to hydrosphere
          • Less leaf litter = no humus = soil can't support new growth = limited amount of carbon absorbed
          • Less trees = more atmospheric CO2 = enhances greenhouse effect = global warming
      • Climate change
        • Increasing temp & decreasing rainfall = drought
          • Amazon  = severe droughts in 2005, 2010
        • (Plants & animals adapted to moist condition) long drought = extinction of species
          • Drought also = forest fires = lots of CO2 released
        • 4 degree temp rise = 85% Amazon rainforest dead = lots carbon released as dead material decomposes = less CO2 taken in by photosynthesis
    • Attempts to limit human impacts on Amazon
      • Selective logging
        • Only some trees felled
        • Felling fewer trees = forest regenerates
      • Replanting
        • Few trees replace those cut down
          • E.g. Peru = 3.2 Mil hectares of forest by 2020
        • Same type of tree replanted = local carbon & water cycles restored to initial state
      • Environmental Law
        • Protects rainforests
          • Laws ban unsustainable wood use
          • Laws ban  excessive logging
          • Laws control land use
            • E.g. Brazilian Forest Code = landowners have to keep 50-80% land as forest
      • Protection
        • National parks, nature reserves protect rainforests
          • E.g.  Central  Amazon Conservation Complex, Brazil, 2003, protects biodiversity, 49,000km2, local people use forest in sustainable way
          • Damaging activities can be monitored & prevented

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