Human Impact on Ecosystems

Ecology – Part II

Renewable Resources

• Can be replaced with time ex. Food supply, water, soil, solar energy, air, soil

Nonrenewable Resources

• Resources that can never be replaced ex. Fossil fuels, minerals and metals

Metals - Aluminum

Minerals - Silicon

Fossil Fuels

Air Pollution

• Air – burning fossil fuels, cars, releases CO2 into atmosphere leads to global warming

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

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

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

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!

DDT moved up food chain

Soil Erosion

• Caused by – overharvesting, deforestation• need to replenish some form of plant growth to

hold soil in place

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

Direct Harvesting

• Destruction or removal of species from their habitats

• Can lead to extinction/decrease in biodiversity

• Laws now protect endangered species

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**

Farming• Only plant 1 type of crop attracts certain

insects• Decrease in biodiversity unstable environment• Soil becomes less fertile

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

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

Acid Rain

• Forms when sulfur and nitrogen compounds mix with moisture in air. (air pollution)

• Lowers the pH of lakes – lowers biodiversity

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

Ozone Depletion

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