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POPULATION AND THE ENVIRONMENT. Population Growth. Population Ecology - the study of the number of individuals of a particular species that are found in an area and how and why those numbers change over time. Population Growth cont’d. Population Density

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Environmental studies


Population growth

Population Growth

Population Ecology

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

Population growth cont d

Population Growthcont’d

Population Density

- the number of individuals of a population per unit of habitat area

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

- e.g., the number of snapper per litre of sea water

Population growth cont d1

Population Growthcont’d

Population Size

- the number of individuals making up a population

Population size changes due to:

• births

• deaths

• immigration

• emigration

Population growth cont d2

Population Growthcont’d

Birth Rate (b)

- also called crude birth rate

- number of birthsper 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 a population in a given year

Fertility rate

Fertility Rate

  • The number of children born to a woman

  • Jamaica’s fertility rate is 2.41

Replacement fertility rate

Replacement Fertility Rate

  • The fertility rate that is high enough to replace an area's population.

  • In Industrialised countries it is 2.1

Population growth cont d3

Population Growthcont’d

Immigration (i)

- movement of individuals into a population

Emigration (e)

- movement of individuals out of a population

Population growth cont d4

Population Growthcont’d

Growth Rate (r)

- also called annual rate of natural population change

r = b – d

r = (b + i) – (d + e)

Biotic Potential

- maximum rate at which a population can increase when there are no limits on its growth

Population growth cont d5

Population Growthcont’d

Exponential Growth

- growth in population size increases by a fixed percentage of the whole in a given time period

- yields a J-shaped curve

Exponential growth cont d

Exponential Growthcont’d

J-shaped Growth Curve

Population growth cont d6

Population Growthcont’d

Environmental Resistance

- all the factors jointly acting to limit the growth of a population

Carrying Capacity

- number of individuals of a given species that can be sustained indefinitely in a given area

S shaped growth curve

S-shaped Growth Curve

Carrying Capacity

A population grows exponentially until it is acted on by limiting factors that cause the growth to level off at the carrying capacity.

Number of Individual Organisms


Regulation of population size

Regulation of Population Size

Density Dependent Checks on Population Growth

- where some limiting factors become more influential as a population’s density increases

- examples:

• competition for resources

• predation

• parasitism

• disease

Regulation of population size1

Regulation of Population Size

Density Independent Checks on Population Growth

- exert their effects on population regardless of population density

- examples:

• floods

• hurricanes

• severe droughts

• fire

• temperature



  • occurs when peopleexceed the carrying capacity of an area

  • more people than can live on Earth or a geographic region in comfort, health & happiness

  • also called environmental unsustainability

  • leaves the planet or region unfit for future generations

Overpopulation cont d


There are 2 types of overpopulation:

1. People Overpopulation

2. Consumption Overpopulation

People overpopulation

People Overpopulation

  • there are more people in the world or in a geographic region than available vital resources can support

  • causes the absolute poverty of 1.2 billion people each year in Less Developed Countries

  • causes 40 million people in Less Developed Countries to die prematurely each year

Consumption overpopulation

Consumption Overpopulation

  • high rates of resource use per person

  • high levels of pollution and environmental degradation per person

  • exists in More Developed Countries, where 1/5 of the world’s people cause significant resource depletion

Factors affecting population growth

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

Environmental studies

2001 Population Data For Selected Countries

Source:CIA World Factbook

Environmental studies

2006 Population Data For Selected Countries

Source:CIA World Factbook

Environmental studies

2011 Population Data For Selected Countries

Source:CIA World Factbook

Population distribution urban living

Population Distribution: Urban Living


- process in which people increasingly move from rural areas to densely populated cities

- Increased density of settlement and/or businesses and other activities over time

Population distribution urban living1

Population Distribution: Urban Living

Urbanisation (Cont’d)

- Approximately 50% of the world's population live in urban areas

- Should increase to 80% by 2025

Urbanisation cont d

Urbanisation (Cont’d)

Factors affecting urbanisation

Pull Factors

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

Push Factors


-Mechanised agriculture

-Government policies / lack of investments

Effects of urbanisation include

Effects of Urbanisation include:

  • Vegetation Loss

  • Urban Microclimate

  • Water Demands, Increased Runoff & Flooding

  • Solid Waste and Pollution

  • Noise Pollution

  • Land Conversion & Social Disruption

Improving urban life some solutions

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



  • Natural Resources Conservation Authority Act

    • Established the NRCA with mandate to ensure effective management of the physical environment of Jamaica

    • Developments over a certain size require a permit but does not necessarily require an EIA or the need to consult with potentially affected communities

    • In 2001 NRCA merged with the Town and Country Planning Department and the Land Development and Utilization Commission to form the National Environment and Planning Agency

Legislations cont d

Legislations cont’d

2. Town and Country Planning Act

  • primary law governing land use in Jamaica

  • Development orders indicate what type of development may take place in an area.

  • Developments that originate from Government do not require planning permission.

  • There is no third party right of appeal.

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