1. Chapter 3 Human Populations

2. Largest population in the world Largest population in the world 1971: government involved 1971: government involved 1979 1979 More aggressive plan More aggressive plan One-child policy One-child policy Why do it? Why do it? Population Growth In China

3. 1984: program relaxed; why? 1984: program relaxed; why? 1970: 5.8 children/woman 1970: 5.8 children/woman 2006: 1.7 children/woman 2006: 1.7 children/woman Ethical issues Ethical issues

4. Population Ecology Branch of biology Branch of biology Study of populations Study of populations Individuals of a particular species Individuals of a particular species How they respond to the environment How they respond to the environment Increase or decrease in number over time Increase or decrease in number over time

5. How Populations Change Global scale: dependent on two things Global scale: dependent on two things Birth rate (b) Birth rate (b) Death rate (d) Death rate (d) Growth rate (r) Growth rate (r) r = b – d r = b – d

6. Local populations Local populations Dispersal Dispersal Immigration (i) Immigration (i) Emigration (e) Emigration (e) How Populations Change

7. Maximum Population Growth Biotic potential Biotic potential Maximum rate at which population can increase Maximum rate at which population can increase Determined by life history characteristics Determined by life history characteristics Large organisms  smallest biotic potentials Large organisms  smallest biotic potentials Microorganisms  largest biotic potentials Microorganisms  largest biotic potentials

8. Exponential Population Growth Optimal conditions Optimal conditions Constant reproductive rate Constant reproductive rate J-shaped curve J-shaped curve

9. Environmental Resistance Unfavorable environmental conditions Unfavorable environmental conditions Prevent reproduction at biotic potential Prevent reproduction at biotic potential Examples? Examples? Environment controls population size: how? Environment controls population size: how?

10. Carrying Capacity Largest population that can be sustained indefinitely Largest population that can be sustained indefinitely Changes in response to environment Changes in response to environment J-shaped curve  S-shaped curve J-shaped curve  S-shaped curve

11. Populations are always changing Populations are always changing Slightly above or below carrying capacity Slightly above or below carrying capacity Too high  crash Too high  crash Carrying Capacity

12. Populations have tripled over past four decades Populations have tripled over past four decades Highest populations ever recorded and still growing Highest populations ever recorded and still growing Human induced land use changes Human induced land use changes Case Study: Overabundant Snow Geese

13. Each spring, millions of birds arrive in the Arctic to breed Each spring, millions of birds arrive in the Arctic to breed Habitat is being destroyed Habitat is being destroyed Long timeframe for habitat recovery Long timeframe for habitat recovery What can be done? What can be done? Case Study: Overabundant Snow Geese

14. The Human Population Currently ≈ 6.6 billion Currently ≈ 6.6 billion people (2006) people (2006) 7 billion by 2013 7 billion by 2013 Why the increase? Why the increase?

15. Thomas Malthus British economist (1766–1834) British economist (1766–1834) Hypothesized that human population would be kept in check: how? Hypothesized that human population would be kept in check: how? Thinking shaped by rapid urbanization & industrialization Thinking shaped by rapid urbanization & industrialization Was he correct? Was he correct?

16. Projecting Future Population World growth rate has declined slightly World growth rate has declined slightly Zero population growth Zero population growth Birth rate = death rate Birth rate = death rate End of 21 st century End of 21 st century U.N. predicts 7.7–10.6 billion by 2050 U.N. predicts 7.7–10.6 billion by 2050

17. Earth’s Carrying Capacity 4 billion – 16 billion people 4 billion – 16 billion people Why such a large range? Why such a large range? What could happen to the environment? What could happen to the environment? Have we already exceeded our carrying capacity? Have we already exceeded our carrying capacity?

18. Demographics Study of populations in various countries Study of populations in various countries Highly developed countries Highly developed countries Low birth rates Low birth rates Low infant Low infantmortality Longer life Longer life expectancies expectancies High GNI PPP High GNI PPP

19. Less developed countries Less developed countries High birth rates High birth rates High infant High infant mortality mortality Shortest life Shortest life expectancies expectancies Low GNI PPP Low GNI PPP Demographics

20. Demographic Transition Country moves from high birth and death rates to low birth and death rates Country moves from high birth and death rates to low birth and death rates Four stages Four stages Preindustrial Preindustrial Transitional Transitional Industrial Industrial Postindustrial Postindustrial

21. Demographic Transition

22. Population is stabilizing in some countries Population is stabilizing in some countries Can all developing countries get there? Can all developing countries get there? Demographic Transition

23. Age Structure Number and proportion of people in each age group in a population Number and proportion of people in each age group in a population Helps predict future population growth Helps predict future population growth Shape is important Shape is important Pyramid = fast growth Pyramid = fast growth Tapered bases = slow or negative growth Tapered bases = slow or negative growth

24. Age Structure Diagrams

25. Future Population Growth Determined by prereproductive individuals Determined by prereproductive individuals Developed vs. developing countries Developed vs. developing countries

26. Population Dynamics in Canada Great Depression of 1930’s meant fewer children Great Depression of 1930’s meant fewer children End of World War II, birth rate increased End of World War II, birth rate increased Baby boomer generation moving toward their sixties Baby boomer generation moving toward their sixties Not all of Canada exhibits the same age structure Not all of Canada exhibits the same age structure What is meant by that? What is meant by that?

27. Age Structure Diagram: Canada

28. Stabilizing World Population Dispersal is not a solution Dispersal is not a solution Increase the death rate? Increase the death rate? Reduce the birth rate! Reduce the birth rate!

29. Culture and Fertility Gender and society Gender and society Different societies have different expectations; impacts fertility rates Different societies have different expectations; impacts fertility rates

30. High TFRs may be traditional High TFRs may be traditional High infant mortality rates High infant mortality rates Children can work Children can work Males more valued Males more valued Religious values Religious values Changing traditions Changing traditions takes time takes time Culture and Fertility

31. Status of Women Gender inequality still exists Gender inequality still exists Most developing countries Most developing countries More illiterate women More illiterate women Fewer women attend secondary school Fewer women attend secondary school Limits women Limits women

32. Low status of women is single most important factor influencing TFR Low status of women is single most important factor influencing TFR Average age at marriage impacts TFR Average age at marriage impacts TFR Sri Lanka: 25; TFR = 2.0 Sri Lanka: 25; TFR = 2.0 Bangladesh: 17; TFR = 3.0 Bangladesh: 17; TFR = 3.0 More education = More education = less children; why? less children; why? Status of Women

33. Family Planning Services Prenatal care, proper birth spacing Prenatal care, proper birth spacing Healthier women  healthier babies Healthier women  healthier babies  fewer infant deaths  lower TFR  fewer infant deaths  lower TFR Provide information and contraceptives Provide information and contraceptives Local social and Local social and cultural beliefs cultural beliefs

34. Government Policies & Fertility Laws determining minimum marriage age Laws determining minimum marriage age Budget for family planning, education, health care, old-age security Budget for family planning, education, health care, old-age security Economic rewards and penalties Economic rewards and penalties Many countries recognize the problem Many countries recognize the problem

35. Population and Urbanization Human population becoming more urbanized Human population becoming more urbanized 80% Canadian population lives in cities; why? 80% Canadian population lives in cities; why?

36. Cities more heterogeneous Cities more heterogeneous More young people in cities More young people in cities Developing countries: more males in cities; why? Developing countries: more males in cities; why? Developed countries: more females in cities; why? Developed countries: more females in cities; why? Population and Urbanization

37. Environmental Problems of Urban Areas Encroachment into habitat Encroachment into habitat Brownfields Brownfields Long commute  more air pollution Long commute  more air pollution Buildup of emissions Buildup of emissions Paved roads, Paved roads, buildings affect buildings affect water flow water flow

38. Environmental Benefits of Urbanization Compact development Compact development Tall, multiple-unit residential buildings close to jobs and shopping districts Tall, multiple-unit residential buildings close to jobs and shopping districts Connected by public transportation Connected by public transportation Reduces pollution Reduces pollution Preserves rural areas Preserves rural areas Requires smart planning! Requires smart planning!

39. Urbanization Trends Currently ≈ 49% world’s population lives in urban areas Currently ≈ 49% world’s population lives in urban areas Most large cities are in developing countries Most large cities are in developing countries If urban growth If urban growth is too fast, basic is too fast, basic services cannot services cannot keep up keep up

40. Urbanization Trends

41. Eco Canada Career Focus Consider a career as an Environmental Planner Consider a career as an Environmental Planner Responsible for balancing the needs of urban living with a sustainable environment Responsible for balancing the needs of urban living with a sustainable environment

42. Case Study: Curitiba, Brazil More than 2.9 million people More than 2.9 million people Compact development Compact development Efficient mass transit system Efficient mass transit system “Big sidewalk” connects downtown “Big sidewalk” connects downtown

43. Purchase of flood-prone properties Purchase of flood-prone properties Now, parks with bicycle paths Now, parks with bicycle paths Garbage Purchase Program Garbage Purchase Program People exchange People exchange garbage for basic garbage for basic needs needs Benefits people Benefits people Case Study: Curitiba, Brazil