1. Human Population Growth

2. History 18001 billion 19302 billion 19603 billion 19754 billion 19875 billion 19996 billion 20096.7 billion

3. History (cont)  Draw graph from Miller & Levine p.143  Most of human history, pop. grew slowly Life was harsh – food was scarce, predators & diseases were common (limiting factors)  Industrial Revolution  exponential growth Better nutrition, sanitation, medicine, & healthcare  lower death rates

4. Determining pop. growth  (Birthrate + Immigration rate (moving in)) – (Deathrate + Emmigration rate (moving out)) = Population growth rate (PGR)  **Unless growth rate becomes zero, pop. continues to grow  Birthrate - # live births per 1000 people / year  Death rate - # deaths per 1000 people / year

5. Age Structure  Proportions of pop. in different age levels Rapid growth – wide base (many children and teenagers) Stable growth – almost equal in each category  M & L p.144 fig 5-13  US: slow, steady growth rate  Guatemala: rapid growth (double in 30 years)

6.  What can you tell about this country based on its age structure graph?  Wide base = rapid growth  Skinny top = poor health care

7.  What can you tell about this country based on its age structure graph?  Base not much wider than middle = slow growth  Balanced fairly evenly throughout ages = good health care  # of females at top = females have longer life expectancy

8.  What can you tell about this country based on its age structure graph?  Base smaller than middle = population decline  Balanced fairly evenly throughout age groups = good health care  # females at top = live longer

9. Biodiversity  Variety of species in a certain area  Is there more biodiversity in … A corn field or a tropical rain forest? A grassland or a coral reef? High Rock Lake or a lake in Brazil?  **Biodiversity is highest closer to the equator

10. Importance  Interdependence of food webs What would happen without insects or decomposers?  Brings stability Monocultures vs. scattered population in a forest  Provides oxygen, carbon dioxide removal, food, genetic material for new crops (drought or pest-resistant), raw materials, medicines

11. Loss  Extinction – species dies, genetics are gone forever Passenger pigeon, Carolina parakeet, dusky seaside sparrow  Endangered – species numbers so low, extinction is possible  Threatened – likely to become endangered

12. Threats  **Habitat loss**  Habitat fragmentation  Edge effects  Habitat degradation (pollution)  Exotic/invasive species

13. What can we do? – sustainable practices  Recycling  Conserve nonrenewable resources Fossil fuels: oil, coal, natural gas, aluminum  Use renewable resources sustainably Solar power, wind, water, forests, crops Sustainable agriculture  Use fewer pesticides, avoid monocultures, drip irrigation, no-till drilling  Be a wise consumer! Vote with your money. Avoid products with excessive plastic packaging, buy in bulk, watch for recycled products, reuse items until they wear out