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HUMANS IN THE BIOSPHERE
A Changing Landscape
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Growing populations depend on the limited natural
resources of earth for survival.
Humans rely on ecological life support systems to
provide us with; clean air, water, and fertile soil.
Humans must be aware that our activities on earth
have an impact on and can change our environment.
Human Activities that Impact Natural
Resources
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Hunting & Gathering:
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Human hunting and gathering causes mass extinction of
animals
Agriculture:
Farming destroyed many forests to make farm land.
(decrease in oxygen, increase in carbon dioxide).
 Fertilizers & pesticides contaminate water supplies
 Irrigation strains water supply
 Food supply demand puts strain on environment( soil
nutrients).
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Industrial Growth & Urban Development:
Makes life easier and more productive
 Causes pollution (Acid rain).
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Renewable & Nonrenewable
Resources
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Renewable Resource: Resource that can regenerate or
be replenished quickly by the earth.
Not unlimited
 Example; Water
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Nonrenewable Resource: Cannot be replenished by
the earth.
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Example; Fossil fuels
Sustainable Development: Using natural resources
without depleting them and still providing for human
need as well as, without causing environmental harm.
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Example: Using lady bugs to eat insects that eat crops
instead of using insecticides/pesticides.
Human Impact on Renewable Resources
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Land Resources: Space for construction, over farming/over
grazing.
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Forest Resources: Wood supplies for building and heat,
oxygen, habitats, food.
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Deforestation-loss of forest that can’t re-grow.
Fishery Resources: Food supply, over fishing.
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Soil Erosion- wearing away of surface soil by air & water.
Desertification-turning farmlands into deserts.
Aquaculture- Raise aquatic animals for human consumption.
Air Resources: Air quality, pollution, burning of fossil fuels,
smog, acid rain.
Freshwater Resources: Only 3 % of water on earth is
freshwater, very limited resources.
The Value of Biodiversity
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Biodiversity- The sum total of the variety of organisms in the
biosphere.
Ecosystem Diversity- Variety of habitats, living communities, and
ecological processes in the living world.
Species Diversity- Number and variations of different species in the
biosphere.
Genetic Diversity- Sum total of all the different forms of genetic
information carried by all organisms living on earth today.
The diversity of life and the diversity environments that they live in
are good indicators of the heath of a species or the ecosystem.
Increased diversity is critical to maintaining the balance of
ecosystems and the biosphere as a whole.
Biodiversity is very important and provided us with many things like
food, medicine, etc.
Threats to Biodiversity
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Extinction- The disappearance of a species from existence in
all parts of its geological range.
Endangered Species- A species whose population size is
rapidly declining and will become extinct if the trend
continues.
Maintaining biodiversity is key to maintaining a stable
environment.
A variety of human activities has and will continue to push
species to become endangered and even to the brink of
extinction.
As endangered species populations decrease so does
genetic diversity.
Habitat Alteration
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Habitat Fragmentation- The splitting of an
ecosystem into smaller sections of fragments of
the original ecosystem. Can lead to the
destruction of ecosystems and the extinction of
species.
 Natural
habitats destroyed
 Species vanish
 Ecosystems split (biological islands): a patch of
one habitat surrounded by another very different
habitat.
Pollution
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Biological Magnification- The increase in the
concentration of a harmful substance in organisms
at higher trophic levels in a food chain or food
web.
 Impacts
the entire food web or food chain but has the
most significant impact on the highest level carnivores. (
increase in toxin levels as consumer consume food it
multiples the concentration levels of the toxins as the
energy flows through the ecosystem).
 Affects food wed
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Example DDT
Introduced Species
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Invasive Species- Plants or animals that have
migrated or been moved from their native
environment to a habitat that they are not native
to.
 Reproduce
rapidly (lack of natural predator).
 Causes major ecological damage to the habitat they
invaded and harm native species.
 Can be devastating to an ecosystem and require
significant changes to prevent the destruction of the
ecosystem or the extinction of specific species.
Conserving Biodiversity
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Conservation- The management of natural
resources, including the preservation of habitats and
wildlife.
Captive Breeding Programs- The raising of animals
in captive but protected environments until they can
be reintroduced and released into their natural wild
habitat.
Charting a Course for the Future
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Ozone Depletion:
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Ozone Layer: high concentration of ozone gas in the earths
atmosphere.
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Absorbs UV radiation (sunscreen for the earth).
Ozone Depletion: the breakdown of the ozone layer.
Caused by CFC’s (chloroflurocarbons).
 CFC’s mostly banned today.
 Scientists predict that damage done to the ozone by CFC’s should
be repaired within 50yrs.
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Global Warming: Increase in the average temperature
of the biosphere.
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Caused by humans; Burning of fossil fuels, deforestation,
landfills, fertilizers.