L6 Population

8/7/2019 L6 Population

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POPULATION AND THE ENVIRONMENT


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Population Growth

Population Ecology

- the study of the number of individuals of aparticular species that are found in an area andhow and why those numbers change over time


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Population Growth contd

Population Density

- the number of individuals of a populationper unit of habitat area

- e.g., the number of Grassquits per hectare

- e.g., the number of snapper per litre of seawater


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Population Size- the number of individuals making up apopulation

Population size changes due to: births deaths immigration

emigration


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Birth Rate (b)- also called crude birth rate- number of births per 1,000 individuals in a

population in a given year

Death Rate (d)

- also called crude death rate- number of deaths per 1,000 individuals in apopulation in a given year


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Fertility Rate

- The number of children born to a woman-

Jamaicas fertility rate is 2.41


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Replacement Fertility Rate

- The fertility rate that is high enough toreplace an area's population.

- In Industrialised countries it is 2.1


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Immigration (i)- movement of individuals into a population

Emigration (e)

- movement of individuals out of a population


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Growth Rate (r)- also called annual rate of natural populationchange

r = b dr = (b + i) (d + e)

Biotic Potential- maximum rate at which a population canincrease when there are no limits on its growth


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Exponential Growth

- growth in population size

increases by a fixed percentage of thewhole in a given time period

- yields a J-shaped curve


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Exponential Growth contd

J-shaped Growth Curve


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Jamaica Population Growth

0

500000

1000000

1500000

2000000

2500000

3000000

1 7 0 0

1 7 2 5

1 7 5 0

1 7 7 5

1 8 0 0

1 8 2 5

1 8 5 0

1 8 7 5

1 9 0 0

1 9 2 5

1 9 5 0

1 9 7 5

2 0 0 0

Year

P o p u l a t i o


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Environmental Resistance- all the factors jointly acting to limit thegrowth of a population

Carrying Capacity

- number of individuals of a given species that

can be sustained indefinitely in a given area


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S-shaped Growth Curve

Time

NumberofIndividual

Organisms

Carrying Capacity

A population growsexponentially until it isacted on by limitingfactors that cause the

growth to level off atthe carrying capacity .


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Regulation of Population Size

Density Dependent Checks on Population Growth- where some limiting factors become more influential as a populations density increases

- examples: competition for resources predation parasitism disease


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Regulation of Population Size

Density Independent Checks on Population Growth

- exert their effects on population regardless of populationdensity

- examples: floods hurricanes severe droughts fire temperature


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Overpopulation

- occurs when people exceed the carrying capacity of anarea

- more people than can live on Earth or a geographicregion in comfort, health & happiness

- also called environmental unsustainability

- leaves the planet or region unfit for future generations


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Overpopulation contd

There are 2 types of overpopulation:

1. People Overpopulation

2. Consumption Overpopulation


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Factors Affecting Population Growth

- Migration- Birth Rate

- Economic Rewards/Penalties - religion, culture

- Empowering Women - average marriage age- Family Planning - children as part of labour force

- Death Rate- AIDS - better nutrition- Crime - availability of good health care

- Economic Development


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Population Distribution: Urban Living

Urbanisation- process in which people increasinglymove from rural areas to densely

populated cities

- Increased density of settlement and/or

businesses and other activities over time


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Population Distribution: Urban Living

Urbanisation (Contd)- Approximately 50% of the world's population

live in urban areas

- Should increase to 80% by 2025


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Urbanisation (Contd)

Factors affecting urbanisationPull Factors

- Cities are the main centres for new jobs,education, innovation , culture & trade

Push Factors - Unemployment- Mechanised agriculture

- Government policies / lack of investments


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Effects of Urbanisation include :

Vegetation Loss

Urban Microclimate

Water Demands, Increased Runoff & Flooding

Solid Waste and Pollution

Noise Pollution

Land Conversion & Social Disruption


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Improving Urban Life (Some Solutions )

reduce population growth

increase investments & social services in

rural areas

repair and revitalise existing cities

grow food in abandoned lots & community

garden plots

l


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Economic Development/Demographic Transition

- hypothesis that countries , as they becomeindustrialised , have declines in death ratesfollowed by declines in birth rates

- the transition takes place in 4 stages1. Pre-Industrial2. Transitional3. Industrial4. Post-Industrial


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1) Pre-Industrial Stage

- harsh living conditions

- high birth rate

- high death rate

2) Transitional Stage

- industrialisation begins

- death rate drops

- birth rate remains high


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3) Industrial Stage

- birth rate drops- birth rate approaches death rate

- population growth slows

4) Post-Industrial Stage

- birth rate equals death rate

- zero population growth


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Age Structure Diagram

- a diagram representing the percentage (or number of people) of the population at each age level in a population

- plots the percentage or numbers of males & females inthe total population


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Pre-Industrial Stage Little Population Growth


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Transitional Stage Rapid Population Growth


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Industrial Stage Population Growth Slows


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Post-Industrial Stage Negative Population Growth

2001 P l ti D t F S l t d C t i


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Source: CIA World Factbook

2001 Population Data For Selected Countries

Country Population BirthsPer 1000Pop.

DeathsPer 1000Pop.

NetMigrationPer 1000

Pop.

PopulationChangePer 1000 Pop.

Aids Deathsin 1999Per 1000 Pop.

(Adult prevalence)

Botswana 1,586,119 28.85 24.18 0 4.7 15.13(35.8%)

Haiti 6,964,549 31.68 15 -2.64 14 3.3(5.17%)

Jamaica 2,665,636 18.12 5.48 -7.52 5.1 0.24 (1.2%)

Barbados 275,330 13.47 8.53 -0.32 4.6 0.47(1.17%)

UnitedStates

278,058,881 14.2 8.7 3.5 9 0.07(0.61%)

Germany 83,029,536 9.16 10.42 4 2.7 0.007(0.1%)

2004 P l ti D t F S l t d C t i


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DeathsPer 1000Pop.


Pop.



(Adult prevalence)

Botswana 1,561,973 24.71 33.63 0 -8.92 21.13(37.3%)

Haiti 7,656,166 33.76 13.21 -3.4 17.15 3.14(5.6%)

Jamaica 2,713,130 16.94 5.4 -4.92 6.62 0.33(1.2%)

Barbados 278,289 12.98 9.08 -0.31 3.59 0.72(1.5%)

UnitedStates

293,027,571 14.13 8.34 3.41 9.2 0.048(0.6%)

Germany 82,424,609 8.45 10.44 2.18 0.19 0.008(0.1%)

2006 Pop lation Data For Selected Co ntries


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DeathsPer 1000Pop.


Pop.



(Adult prevalence)

Botswana 1,639,833 23.08 29.5 6.07 -0.35 21.13(37.3%)

Haiti 8,308,504 36.44 12.17 -1.31 22.96 3.14(5.6%)

Jamaica 2,758,124 20.82 6.52 -6.27 8.03 0.33(1.2%)

Barbados 279,912 12.71 8.67 -0.31 3.73 0.72(1.5%)

UnitedStates

298,444,215 14.14 8.26 3.18 9.06 0.048(0.6%)

Germany 82,422,299 8.25 10.62 2.18 -0.19 0.008(0.1%)



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DeathsPer 1000Pop.


Pop.


(Fert)

Aids Deathsin 2007(People living with

AIDS)

Botswana 1,990,876 22.89 8.52 5 19.37(2.6)

11000(300000)

Haiti 9,035,536 29.1 8.65 -2.07 18.38(3.81)

7200(120000)

Jamaica 2,825,928 19.68 6.43 -5.7 7.52(2.25)

1500(27000)

Barbados 284,589 12.55 8.41 -0.31 3.83(1.68)

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L6 Population