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Ecosystems and Human Impact

Ecosystems and Human Impact. Humans in the Mix. (Are Humans Natural?). Natural Systems vs. Human Modified Systems… Impacts on: Biodiversity: Genetic Diversity: Species Diversity: Ecological Diversity:. variety of different versions of the same genes within a population

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Ecosystems and Human Impact

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  1. Ecosystems andHuman Impact

  2. Humans in the Mix (Are Humans Natural?) • Natural Systems vs. Human Modified Systems… • Impacts on: • Biodiversity: • Genetic Diversity: • Species Diversity: • Ecological Diversity: • variety of different versions of the same genes within a population • varieties of different kinds of organisms within a community / ecosystem • complexity within a community (food chains / webs / trophic levels, number of niches, types of biomass produced

  3. Biodiversity “Hot Spots”

  4. But why do we care about biodiversity? • Keystone Species • Drugs / Medicines ($30m / year!) • Earth is one big ecosystem—every animal has a role: Darwin would say if it didn’t have a role, it wouldn’t be here. • Entertainment / Human Interest…

  5. Laws of Human Ecology • 1st Law of Human Ecology • You Can Never Do Just One Thing • Principle of Interconnectedness • 2nd Law of Human Ecology • There is no “away”

  6. Humans in the Mix Ecosystem Complexity and Resilience (“Natural” Evolution) vs. Ecosystem Simplification (Human Impact)

  7. Simplification. • Overuse of Pesticides • Eliminating Some Predators • Deliberately or Accidentally Introducing New Species • Over-Harvesting Potentially Renewable Resources • Interfering with the Normal Chemical Cycling and Energy Flows First Law of Human Ecology

  8. Pesticides: DDT(DDT: Dichloro-Diphenyl-Trichloroethane) • One of the first synthetic pesticides • Developed in WWII: Malaria, other insects • Applications in Ag Industry Post-War • Nearly wiped out MANY species in U.S.

  9. Impact of DDT • Endangerments / Near extinction of many raptors • Softened egg shells, chicks never develop • Found to be a carcinogen • Banned in U.S. in 1972 Peregrine Falcon California Condor Osprey

  10. DDT: Sidenote • DDT still permitted in many tropical (Global South) countries • Used as deterrent against malaria • 1m people die of malaria worldwide (CDC) every year • 90% in Africa Q: • Is DDT good? • Is DDT bad?

  11. Elimination of Predators “Trophic Cascade” http://www.buzzfeed.com/summeranne/how-wolves-change-rivers-is-the-perfect-explanation-of-ecolo

  12. Canada

  13. Exotic Species Wild Boar

  14. Kudzu

  15. Backyard Bird Feeders? • Natural or Unnatural? • Upsetting the homeostasis of the local ecosystem? • What happens if there are too many birds—and birds from elsewhere? • What happens if you quit feeding them after they multiply?

  16. Over-Harvesting Potentially Renewable Resources

  17. Species Response to Change • Homeostasis The ability for any living thing (ecosystem included) to regulate and maintain a flexible, steady living system • Sustainability: “The capacity to endure”

  18. Species Response to Change • Homeostasis • Stability and Resilience • Inertia (resistance) • Renewal(how well can a given species bounce back?) • Constancy(persistence and stability)

  19. (too much?)Inertia!

  20. Renewal

  21. Constancy

  22. Species Response to Change • Homeostasis • Stability and Resilience • Population Dynamics • Controls • Environmental Resistance • “Carrying Capacity” • Abiotic and Biotic Influences on Plant and Animal Populations

  23. (Relatively) Stable Bobcat Population in Wisconsin

  24. Hare and Lynx Pop: Canada Cyclic

  25. Irruptive Change Curve

  26. Interfering with the Normal Chemical Cycling and Energy Flows

  27. Colorado River

  28. Lake Mead

  29. 2nd Law: Garbage Mountain

  30. The North Pacific Gyre “Garbage Island” http://www.youtube.com/watch?v=Lt-MivNezes&feature=related

  31. Human Impact • With technology, the impact of humans has never been more dramatic • Extinction is “natural,” but the current rate of extinction has never existed due to forces beyond “naturally” occurrences: • Ice age • Asteroid hitting earth? • Eruption and release of global volcanic ash? • Floods? Tsunamis? • Averaging 2-3 extinctions per decade • What’s the final impact if we can “never do just one thing?” http://www.cleanair.org/program/waste_and_recycling/recyclenow_philadelphia/waste_and_recycling_facts

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