Chapter 7 Human Population Change and the Environment

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Chapter 7 Human Population Change and the
Environment
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Population Growth In China

• Largest population in the world
• 1971 government involved
• 1979
• More aggressive plan
• One-child policy
• Why do it?

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Population Growth In China

• 1984 program relaxed why?
• 1970 5.8
  children/woman
• 2006 1.7
  children/woman
• Ethical issues

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Population Ecology

• Branch of biology
• Study of populations
• Individuals of a given species
• How they respond to the environment
• Look for similarities

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How Populations Change

• Global scale dependent on two things
• Birth rate (b)
• Death rate (d)
• Growth rate (r)
• r b - d

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How Populations Change

• Local populations
• Dispersal
• Immigration (i)
• Emigration (e)

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Maximum Population Growth

• Biotic potential
• Maximum rate at which population can increase
• Determined by life history characteristics
• Large organisms ---gt smallest biotic potentials
• Microorganisms ---gt largest biotic potentials

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Exponential Population Growth

• Optimal conditions
• Constant reproductive rate
• J-shaped curve

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Environmental Resistance

• Unfavorable environmental conditions
• Prevent reproduction at biotic potential
• Examples?
• Environment controls population size how?

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Carrying Capacity

• Largest population that can be sustained
  indefinitely
• Changes in response to environment
• J-shaped curve ---gt S-shaped curve

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Carrying Capacity

• Populations are always changing
• Slightly above or below carrying capacity
• Too high ---gt crash

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The Human Population

• Currently 6.5 billion
  people
• 7 billion by 2013
• Why the increase?

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Thomas Malthus

• British economist
• Hypothesized that human population would be kept
  in check how?
• Thinking shaped by rapid urbanization
  industrialization
• Was he correct?

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Projecting Future Population

• World growth rate has declined slightly
• Zero population growth
• Birth rate death rate
• End of 21st century
• U.N. predicts 7.9-10.9 billion by 2050

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Earths Carrying Capacity

• 4 billion 16 billion people
• Why such a large range?
• What could happen to the environment?
• Have we already exceeded our carrying capacity?

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Demographics

• Study of populations
• Highly developed countries
• Low birth rates
• Low infant mortality
• Longer life expectancies
• High GNI PPP

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Demographics

• Less developed countries
• High birth rates
• High infant
  mortality
• Shortest life expectancies
• Low GNI PPP

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Total Fertility Rate

• TFR average number of children born to each
  woman
• Replacement rate 2.1
• Current TFR

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Demographic Transition

• Country moves from high birth and death rates to
  low birth and death rates
• Four stages
• Preindustrial
• Transitional
• Industrial
• Postindustrial

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Demographic Transition
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Demographic Transition

• Population is stabilizing in some countries
• Can all developing countries get there?

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Age Structure Diagrams
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Age Structure

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

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Future Population Growth

• Determined by prereproductive individuals
• Developed vs. developing countries

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Stabilizing World Population

• Dispersal is not a solution
• Increase the death rate?
• Reduce the birth rate!

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Culture and Fertility

• Gender and society
• Different societies have different expectations
  impacts fertility rates

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Culture and Fertility

• High TFRs may be traditional
• High infant mortality rates
• Children can work
• Males more valued
• Religious values
• Changing traditions takes
  time

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Status of Women

• Gender inequality still exists
• Most developing countries
• More illiterate women
• Fewer women attend secondary school
• Limits women

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Status of Women

• Low status of women is single most important
  factor influencing TFR
• Average age at marriage impacts TFR
• Sri Lanka 25 TFR 2.0
• Bangladesh 17 TFR 3.0
• More education
  less children why?

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Family Planning Services

• Prenatal care, proper birth spacing
• Healthier women ---gt healthier babies ---gt
  fewer infant deaths ---gt lower TFR
• Provide information and contraceptives
• Local social and
  cultural beliefs

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Government Policies Fertility

• Laws determining minimum marriage age
• Budget for family planning, education, health
  care, old-age security
• Economic rewards and penalties
• Many countries recognize the problem

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Population and Urbanization

• Human population becoming more urbanized
• 79 U.S. population lives in cities why?

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Urbanization Trends
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Urbanization Trends

• Currently 47 worlds population lives in urban
  areas
• Most large cities are in developing countries
• If urban growth
  is too fast, basic
  services cannot
  keep up

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Environmental Problems of Urban Areas

• Encroachment into habitat
• Brownfields
• Long commute ---gt more air pollution
• Buildup of emissions
• Paved roads,
  buildings affect
  water flow

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Environmental Benefits of Urbanization

• Compact development
• Tall, multiple-unit residential buildings are
  close to shops and jobs
• Connected by public transportation
• Reduces pollution
• Preserves rural areas
• Requires smart planning!

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Case Study Curitiba, Brazil

• More than 2.5 million people
• Compact development
• Efficient mass transit system
• Big sidewalk connects downtown

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Case Study Curitiba, Brazil

• Purchase of flood-prone properties
• Now, parks with bicycle paths
• Garbage Purchase
• People exchange garbage
  for basic needs
• Benefits people