Lecture 9

• Primary Land cover: natural vegetation that has never been disturbed by human activities
• Secondary land cover: natural vegetation that is recovering from human activities - can be very young or as mature as primary
• Land use: how humans are using the land e.g. agriculture, urban areas
• Land-use change:

  • agriculture - clearing forests for fertile soil and pasture
  • abandon of agriculture - less managed land that leads to more natural disasters such as forest fires
  • urbanisation
  • evaporation of large bodies of water e.g. Aral Sea
  • subsistence farmers clearing land for pasture
• Land use change:

  • causes negative effects on biodiversity
  • harmful pesticides and fertilisers - lead to dead zones
• Control variables:

  • Global: area of forested land as % of original forest cover
  • Biome: area of forested land as % of potential forest

  Current value; Global - 62%
• Planetary Boundary:

  • Global: 75%
  • Biome: - Tropical; 85%, Temperature;50%, Boreal;85%
• Importance of Amazon Rainforest:

  • biodiversity - food, medicines, stability/resilience
  • helps regulate planet's atmosphere - transpiration
  • carbon sequestration - capture around 5 billion tons of CO2
  • resources like wood
• Deforestation causes:

  • clearing of land for agriculture
  • urbanisation
  • wildfires
  • climate change/drought
• Deforestation:

  • Atmosphere - loss of carbon sinks, air quality
  • Lithosphere - monocropping, disrupt natural biogeochemical flows, natural changes
  • Hydrosphere - chemical pollution, risk of flooding, dead zones, irrigation
  • Biosphere - loss of habitat and diversity