Human Impact on Ecosystems
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Transcript of Human Impact on Ecosystems
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Human Impact on Ecosystems
Ecology – Part II
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Renewable Resources
• Can be replaced with time ex. Food supply, water, soil, solar energy, air, soil
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Nonrenewable Resources
• Resources that can never be replaced ex. Fossil fuels, minerals and metals
Metals - Aluminum
Minerals - Silicon
Fossil Fuels
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Air Pollution
• Air – burning fossil fuels, cars, releases CO2 into atmosphere leads to global warming
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Greenhouse Effect
• Caused by burning fossil fuels• Leads to global warming• CO2 traps heat radiation and reflects it back
toward earth• Polar ice caps melt leads to flooding
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Global Warming – Greenhouse Effect
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Water Pollution
Water – easy disposal site harmful to organisms that live there-Sewage + animal waste = fertilizer- Plants and algae flourish – use up all oxygen everything else suffocates
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Thermal Pollution
• Power plants and factories use water to cool machines
• Dump the heated water back • Warm water holds less oxygen some species
die• Most aquatic organisms are cold-blooded
cannot survive rapid changes in temperature
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Toxic Wastes• Phosphates from detergents, fertilizers,
pesticides• These chemicals collect in living cells• Increase in level as you move up the food chain• Algae (small amt.) Tertiary consumers (large
amt.)• Ex. DDT (pesticide)- caused birds to lay eggs with
very thin shells – eggs cracked too early!
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DDT moved up food chain
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Soil Erosion
• Caused by – overharvesting, deforestation• need to replenish some form of plant growth to
hold soil in place
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Carrying Capacity
• Total # of organisms that can exist in a given area. Population levels off right around carrying capacity line.
• Fear humans will reach or pass CC line – result famine, disease, and wars over resources
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Direct Harvesting
• Destruction or removal of species from their habitats
• Can lead to extinction/decrease in biodiversity
• Laws now protect endangered species
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Deforestation • Destruction of forests for human activity • Creates an increase in CO2 in the atmosphere –
these trees would normally use CO2 for photosynthesis
• Increase in CO2 in atmosphere leads to global warming
• Solution: For every tree cut down plant 2 more.**Reforestation**
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Farming• Only plant 1 type of crop attracts certain
insects• Decrease in biodiversity unstable environment• Soil becomes less fertile
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Insect/Pest problems
• Using pesticides is harmful to the environment – causes harm to some organisms
• Alternatives –• Introduce natural enemies or predators• Infect pest with virus or bacteria• Use pheromones (sex hormones) to lure pests into
traps• Release sterilized males – can’t reproduce
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Imported Species• many imported species become pests they
are not a natural part of the area.• They have no natural predator – overpopulation
of the organism occurs• Ex. Japanese beetles, gypsy moths, zebra
mussles • Solution – strict laws, introduce a natural
predator
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Acid Rain
• Forms when sulfur and nitrogen compounds mix with moisture in air. (air pollution)
• Lowers the pH of lakes – lowers biodiversity
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Ozone Depletion
• Protects earth from suns radiation(uv)• Thinning or hole in layer allows too much UV
– Causes: mutations, skin cancer, kills cells, kills producers
* CFC’s caused hole – from aerosol cans
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Ozone Depletion
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