Transcript Chapter 6 Powerpoint

WHAT IS WRONG WITH THE
WORLD TODAY
• Working with a partner brainstorm as many
environmental problems as possible.
• Think about things that see or hear on the news
that not only affect us but all living things.
• Remember that all living things in nature are
connected so overlapping problems are ok.
Chapter 6: Humans in the
Biosphere
6-1 A Changing Landscape
A Changing Landscape
• Earth as a Island
– Human population is growing, but the Earth is not.
– We are increasing demands on air, H20, and land.
• Human Activities
– We use as much energy as all other multicellular
species combined.
– Humans change the flow of energy and reduce
ecosystem’s ability to recycle.
Hunting and Gathering
•
•
•
People were nomads, traveling to
take advantage of movement and
cycles of animals and plants.
Subsistence Hunting: taking only
necessities, and making few
demands on the Earth.
Ways the nomads changed the
environment:
1.
2.
3.
Build dams
Burned Grassland
Caused mass extinction of large
animals
Agriculture
• Farming gave humans a
dependable source of food.
– Allowed humans to stay in one
place.
– Lead to the formation of towns
and cities.
• Domestication of Animals
– Pros: milk, meat, hides, wool,
companionship, energy to do
work
– Cons: overgrazing, soil
erosion, H2O supply strain
The Green Revolution
• Green Revolution: 1950’s, new intensive farming
practices to increase crop yield.
• Monoculture: large fields were cleared and
planted with a single crop year after year.
• Pros of Green Revolution
– More food, “miracle strains”, larger equipment and
machinery.
• Cons of Green Revolution
– Deplete H2O and energy, pest reproduction, fertilizer
interferes with food webs.
Industrial Growth and Urban
Development
• Industrial Revolution:
1800’s, addition of factories
and machines to civilation
• Effects of Industrial
Revolution
– Use of more fossil fuels
– Production of waste
• Suburban Sprawl: living
around cities
– More stress on plants and
animals
6-2: Renewable and
Nonrenewable Resources
• Common Resource: “owned” by many people.
• Tragedy of the Commons
– Common resources will be eventually destroyed
because no one is responsible for preserving it.
Sustainable Use
• Renewable Resources: can be
replenished or regenerated but not
unlimited.
Ex: trees and water
• Nonrenewable Resource: cannot be
replenished
Ex: fossil fuels, old-growth forest
• Sustainable Use: way of using
natural resources at a rate that does
not deplete them
Ex: using lady bugs to eat pests
instead of pesticides.
Land Resources
• Food crops grow best in soil that is a mixture
of humus, sand, clay and rock.
• Plowing removes the roots of grasses that
hold soil in place
– Increases the rate of soil erosion
• Desertification: Combination of drought,
farming, overgrazing turns areas into deserts
Land Resources
• Ways we guard against
soil erosion:
– Contour plowing
– Leaving stems/roots of
previous year’s crop
– Planting rye instead of
leaving field bare
– Irrigation systems
– Wind breaks
Invasive Species
Forest Resources
• Ways in which forests
provide ecological services
– Take out CO2, provide O2
– Products (wood, paper,
lumber, fuel)
– Store nutrients
– Provide habitats food for
organisms
– Limit soil erosion
Forest Resources
• Old-growth Forest: never have been cut
– Nonrenewable b/c takes centuries to grow back
• Deforestation: loss of forest
– Soil erosion
– Laterite: soil that has been chemically change
to a hard brick-like material
Ocean Resources
• Over fishing: fish are harvested faster than
they can reproduce; leads to destruction of
fisheries
Ex: cod, salmon, herring, king crab
• Aquaculture: farming of aquatic organisms
Water Resources
• Water is renewable, but
the supply is limited
• Ways to ensure the
sustainable use of water:
– Protect systems involved
in H2O cycle
Ex: wetlands purify
water
– Preserve forests and
vegetation
Air Resources
• Smog: a mixture of
chemical the occurs as a
gray-brown haze in the
atmosphere.
– Caused by car exhaust,
industrial emissions, and
burning fossil fuels.
• Particulates – microscopic
particles of ash and dust
• Acid Rain: water mixes
with nitrogen and sulfur
gases to form acid rain
Invasive Species
6-3: Biodiversity
• Biodiversity: sum total of genetically based
variety of all organisms
• Human threats to biodiversity:
–
–
–
–
Altering habitats
Hunting to extinction
Pollution
Introducing foreign species to new environments
Conserving Biodiversity
• Conservation: wise management of natural
resources (preservation of habitats and wildlife)
• Ecological Hotspot: where habitats/species are in
immediate danger of extinction
6-4 Charting a Course for the Future
•
Two major global changes
1. Global Warming
2. Ozone layer depletion – protects from UV
radiation
• Overexposure to UV radiation can cause cancer.
• The major cause of ozone depletion is CFC’s
Ex: aerosol cans, Styrofoam, coolants in fridge