Human Impact on Ecosystems

1. Human Impact on Ecosystems Ecology – Part II

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

3. Nonrenewable Resources • Resources that can never be replaced ex. Fossil fuels, minerals and metals Minerals - Silicon coal Metals - Aluminum Fossil Fuels

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

5. 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

6. Global Warming – Greenhouse Effect

7. 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

8. 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

9. 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!

10. DDT moved up food chain

11. Soil Erosion • Caused by – overharvesting, deforestation • need to replenish some form of plant growth to hold soil in place

12. 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

13. Direct Harvesting • Destruction or removal of species from their habitats • Can lead to extinction/decrease in biodiversity • Laws now protect endangered species

14. 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**

15. Farming • Only plant 1 type of crop attracts certain insects • Decrease in biodiversity  unstable environment • Soil becomes less fertile

16. 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

17. 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

18. Acid Rain • Forms when sulfur and nitrogen compounds mix with moisture in air. (air pollution) • Lowers the pH of lakes – lowers biodiversity

19. 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

20. Ozone Depletion