Chapter 3 Chapter 3 Human PopulationsHuman Populations

Largest population in the worldLargest population in the world 1971: government involved1971: government involved 19791979

More aggressive planMore aggressive plan One-child policyOne-child policy Why do it?Why do it?

Population Growth In ChinaPopulation Growth In China

Population Growth In ChinaPopulation Growth In China 1984: program relaxed; why?1984: program relaxed; why? 1970: 5.8 children/woman1970: 5.8 children/woman 2006: 1.7 children/woman2006: 1.7 children/woman Ethical issuesEthical issues

Population EcologyPopulation Ecology Branch of biologyBranch of biology Study of populationsStudy of populations

Individuals of a particular speciesIndividuals of a particular species How they respond to the environmentHow they respond to the environment Increase or decrease in number over Increase or decrease in number over

timetime

How Populations ChangeHow Populations Change Global scale: dependent on two thingsGlobal 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 – dr = b – d

Local populationsLocal populations DispersalDispersal

Immigration (i)Immigration (i) Emigration (e)Emigration (e)

How Populations ChangeHow Populations Change

Maximum Population Maximum Population GrowthGrowth

Biotic potentialBiotic potential Maximum rate at which population Maximum rate at which population

can increasecan increase Determined by life history Determined by life history

characteristicscharacteristics Large organisms Large organisms smallest biotic smallest biotic

potentialspotentials Microorganisms Microorganisms largest biotic largest biotic

potentialspotentials

Exponential Population GrowthExponential Population Growth Optimal conditionsOptimal conditions Constant Constant

reproductive ratereproductive rate J-shaped curveJ-shaped curve

Environmental ResistanceEnvironmental Resistance

Unfavorable environmental Unfavorable environmental conditionsconditions

Prevent reproduction at biotic Prevent reproduction at biotic potentialpotential

Examples?Examples? Environment controls population size: Environment controls population size:

how? how?

Carrying CapacityCarrying Capacity Largest population that can be Largest population that can be

sustained indefinitelysustained indefinitely Changes in response to environmentChanges in response to environment J-shaped curve J-shaped curve S-shaped curve S-shaped curve

Populations are always changingPopulations are always changing Slightly above or below carrying Slightly above or below carrying

capacitycapacity Too high Too high crash crash

Carrying CapacityCarrying Capacity

Populations have Populations have tripled over past tripled over past four decadesfour decades

Highest populations Highest populations ever recorded and ever recorded and still growingstill growing

Human induced Human induced land use changesland use changes

Case Study: Overabundant Case Study: Overabundant Snow GeeseSnow Geese

Each spring, millions of birds arrive in Each spring, millions of birds arrive in the Arctic to breedthe Arctic to breed

Habitat is being destroyedHabitat is being destroyed Long timeframe for habitat recoveryLong timeframe for habitat recovery What can be done? What can be done?

Case Study: Overabundant Case Study: Overabundant Snow GeeseSnow Geese

The Human PopulationThe Human Population

Currently ≈ 6.6 billion Currently ≈ 6.6 billion

people (2006)people (2006) 7 billion by 20137 billion by 2013 Why the increase?Why the increase?

Thomas MalthusThomas Malthus British economist (1766–1834)British economist (1766–1834) Hypothesized that human population Hypothesized that human population

would be kept in check: how?would be kept in check: how? Thinking shaped by rapid Thinking shaped by rapid

urbanization & industrializationurbanization & industrialization Was he correct?Was he correct?

Projecting Future PopulationProjecting Future Population World growth rate has World growth rate has

declined slightlydeclined slightly Zero population growthZero population growth

Birth rate = death rateBirth rate = death rate End of 21End of 21stst century century

U.N. predicts 7.7–10.6 U.N. predicts 7.7–10.6 billion by 2050billion by 2050

Earth’s Carrying CapacityEarth’s Carrying Capacity

4 billion – 16 billion people4 billion – 16 billion people Why such a large range?Why such a large range? What could happen to the What could happen to the

environment?environment? Have we already exceeded our Have we already exceeded our

carrying capacity?carrying capacity?

DemographicsDemographics Study of populations in various countriesStudy of populations in various countries Highly developed countriesHighly developed countries

Low birth ratesLow birth rates Low infantLow infant

mortalitymortality Longer life Longer life

expectanciesexpectancies High GNI PPPHigh GNI PPP

Less developed countriesLess developed countries High birth ratesHigh birth rates High infant High infant

mortalitymortality Shortest life Shortest life

expectanciesexpectancies Low GNI PPPLow GNI PPP

DemographicsDemographics

Demographic TransitionDemographic Transition

Country moves from high birth and Country moves from high birth and death rates to low birth and death death rates to low birth and death ratesrates

Four stagesFour stages PreindustrialPreindustrial TransitionalTransitional IndustrialIndustrial PostindustrialPostindustrial

Demographic TransitionDemographic Transition

Population is stabilizing in some Population is stabilizing in some countriescountries

Can all developing countries get there?Can all developing countries get there?

Demographic TransitionDemographic Transition

Age StructureAge Structure Number and proportion of people in Number and proportion of people in

each age group in a populationeach age group in a population Helps predict future population growthHelps predict future population growth Shape is importantShape is important

Pyramid = fast growthPyramid = fast growth Tapered bases = slow or negative Tapered bases = slow or negative

growthgrowth

Age Structure DiagramsAge Structure Diagrams

Future Population GrowthFuture Population Growth Determined by prereproductive Determined by prereproductive

individualsindividuals Developed vs. developing countriesDeveloped vs. developing countries

Population Dynamics in Population Dynamics in CanadaCanada

Great Depression of 1930’s meant fewer Great Depression of 1930’s meant fewer childrenchildren

End of World War II, birth rate increasedEnd of World War II, birth rate increased Baby boomer generation moving toward Baby boomer generation moving toward

their sixtiestheir sixties Not all of Canada exhibits the same age Not all of Canada exhibits the same age

structurestructure What is meant by that?What is meant by that?

Age Structure Diagram: Age Structure Diagram: CanadaCanada

Stabilizing World PopulationStabilizing World Population

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

Culture and FertilityCulture and Fertility Gender and societyGender and society Different societies have different Different societies have different

expectations; impacts fertility ratesexpectations; impacts fertility rates

High TFRs may be traditionalHigh TFRs may be traditional High infant mortality ratesHigh infant mortality rates Children can workChildren can work Males more valuedMales more valued Religious valuesReligious values Changing traditions Changing traditions

takes timetakes time

Culture and FertilityCulture and Fertility

Status of WomenStatus of Women Gender inequality still existsGender inequality still exists Most developing countriesMost developing countries

More illiterate womenMore illiterate women Fewer women attend secondary Fewer women attend secondary

schoolschool Limits womenLimits women

Low status of women is single most Low status of women is single most important factor influencing TFRimportant factor influencing TFR

Average age at marriage impacts TFRAverage age at marriage impacts TFR Sri Lanka: 25; TFR = 2.0Sri Lanka: 25; TFR = 2.0 Bangladesh: 17; TFR = 3.0Bangladesh: 17; TFR = 3.0

More education = More education =

less children; why?less children; why?

Status of WomenStatus of Women

Family Planning ServicesFamily Planning Services Prenatal care, proper birth spacingPrenatal care, proper birth spacing Healthier women Healthier women healthier babies healthier babies

fewer infant deaths fewer infant deaths lower TFR lower TFR Provide information and contraceptivesProvide information and contraceptives Local social and Local social and

cultural beliefscultural beliefs

Government Policies & Government Policies & FertilityFertility

Laws determining minimum marriage Laws determining minimum marriage ageage

Budget for family planning, education, Budget for family planning, education, health care, old-age securityhealth care, old-age security

Economic rewards and penaltiesEconomic rewards and penalties Many countries recognize the problemMany countries recognize the problem

Population and UrbanizationPopulation and Urbanization Human population becoming more Human population becoming more

urbanizedurbanized 80% Canadian population lives in cities; 80% Canadian population lives in cities;

why?why?

Cities more heterogeneousCities more heterogeneous More young people in citiesMore young people in cities Developing countries: more males in Developing countries: more males in

cities; why?cities; why? Developed countries: more females in Developed countries: more females in

cities; why? cities; why?

Population and UrbanizationPopulation and Urbanization

Environmental Problems of Environmental Problems of Urban AreasUrban Areas

Encroachment into habitatEncroachment into habitat BrownfieldsBrownfields Long commute Long commute more air pollution more air pollution Buildup of emissionsBuildup of emissions Paved roads, Paved roads,

buildings affect buildings affect

water flowwater flow

Environmental Benefits of Environmental Benefits of UrbanizationUrbanization

Compact developmentCompact development Tall, multiple-unit residential buildings Tall, multiple-unit residential buildings

close to jobs and shopping districtsclose to jobs and shopping districts Connected by public transportationConnected by public transportation Reduces pollutionReduces pollution Preserves rural areasPreserves rural areas

Requires smart planning!Requires smart planning!

Urbanization TrendsUrbanization Trends

Currently ≈ 49% world’s population Currently ≈ 49% world’s population lives in urban areaslives in urban areas

Most large cities are in developing Most large cities are in developing countriescountries

If urban growth If urban growth is too fast, basic is too fast, basic services cannot services cannot keep upkeep up

Urbanization TrendsUrbanization Trends

Eco Canada Career FocusEco Canada Career Focus Consider a career as Consider a career as

an Environmental an Environmental PlannerPlanner

Responsible for Responsible for balancing the needs balancing the needs of urban living with of urban living with a sustainable a sustainable environmentenvironment

Case Study: Curitiba, BrazilCase Study: Curitiba, Brazil More than 2.9 million peopleMore than 2.9 million people Compact developmentCompact development Efficient mass transit systemEfficient mass transit system ““Big sidewalk” connects downtownBig sidewalk” connects downtown

Purchase of flood-prone propertiesPurchase of flood-prone properties Now, parks with bicycle pathsNow, parks with bicycle paths Garbage Purchase ProgramGarbage Purchase Program

People exchange People exchange

garbage for basic garbage for basic

needsneeds Benefits peopleBenefits people

Case Study: Curitiba, BrazilCase Study: Curitiba, Brazil