Chapter 6

							   Chapter 6

Humans in the
  Biosphere
             Section 6-1
        A Changing Landscape
• Earth’s organisms share limited resources
• Humans are the main source of
  environmental change.
• Human activities that affect the biosphere:
  – Hunting & gathering
  – Agriculture
  – Industry
  – Urban development
        Hunting & gathering

• Prehistoric hunters and gatherers changed
  the environment by hunting some animals
  to extinction.
              Agriculture
• Farming increased the amount of food
  produced.
• More food meant that cities were able to
  develop. (people in cities = more waste)
• Advances in pesticides = more pollution
• Monoculture = same crops year after
  year
                Industry
• After the Industrial Revolution more
  resources were used and more pollution
  was produced.
        Urban Development
• Cities and urban areas require energy in
  order to maintain the lifestyle that people
  are used to.
• Fossil fuels are being used in order to
  obtain the energy needed for our urban
  and city live styles
          Section 6-2
    Renewable & Nonrenewable
           resources
• Two types of resources:
  – Renewable Resources: those that natural
    processes can replace
    • Ex- water, oxygen, forests    O2
  – Nonrenewable Resources: those that cannot
    be replaced by natural processes:
    • Ex- Fossil fuels
• Human activities threaten many resources.
• These activities can affect the quality and supply
  of renewable resources (land, forests, fisheries,
  air and fresh water)
• Sustainable Development (SD) is …
  – A way of using natural resources without depleting
    them.
  – A way of providing for human needs without causing
    long-term environmental harm
• In order to work well, SD must take into account:
  – 1) how ecosystems function
  – 2)how human economic systems work
            Land Resources
• Soil erosion: wearing away of surface soil
  by water and wind
  – Over farming, drought, overgrazing & plowing
    can cause soil erosion and desertification
• Deforestation is loss of forests
         Forest Resources
•Forests --provide wood, paper, remove
CO2. produce O2, store nutrients, provide
habitats and food for organisms,
moderate climate, limit soil erosion &
protect freshwater supply
• Not all forest are renewable resources.
    (old growth forests are non-renewable)
• Forest Management – not all trees are
  cut (young trees are saved, new trees
  are planted)




                                   Healthy Forest -
                                   Logged in 1930's
        Fishery Resources
• Over fishing has threatened the survival of
  many species
• Governments have set up guidelines for
  commercial fishing
• Aquaculture –When fish are raised by
  humans for food.
                Air Resources
   • Smog – a mixture of chemicals in the air
     giving it a gray-brown haze. (caused by
     automobile exhaust and industries)
   • Pollutants- harmful material that enter the
     air land or water.     Smog in Miami, Florida




Smog in Japan
           6-3 Biodiversity
• Diversity = Variety
• Biodiversity = variety of all the organisms
  in the biosphere.
  – Ecosystem Diversity
  – Species Diversity
  – Genetic Diversity
• Human activity can reduce biodiversity by:
  – Altering habitats (including habitat fragmentation)
  – Hunting species to extinction
  – Polluting the environment
  – Introducing foreign species to new
    environments
Burmese Python vs. American Alligator
The Convention on International Trade
      in Endangered Species
Bans international trade in products that
come from endangered species
                      Pollution
• Biological
  Magnification –
  Concentration of
  harmful substances
  increase in
  organisms at higher
  trophic levels.
 • See figure 6-16 on page
             152
     6-4 Charting a course for the
                Future
• Researchers are
  gathering data to
  monitor and evaluate
  the effects of human
  activities on important
  systems in the
  biosphere
  – (1) Ozone Layer
  – (2) Global Climate
    System