Population
By: Rebecca Marty
Formula for Population
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Actual rate of population change can be
determine by an Formula:
Actual Growth rate (%) = birth rate- death
rate divided by 10
Ex. The United states had a birth rate of 14.6
live births per 1,000 population in one year.
The death rate in that year for the United
States was 8.3 deaths per 1,000 population.
Calculate the Population Growth rate (%) for
the United States in that year.
Distribution
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In 1800, the vast majority of the world’s
population (65 %) resided in Asia and Europe.
Between 2000 and 2030, most of the growth
will occur at the less- developed countries in
Africa, Asia, and Latin America whose growth
rates are much higher than those in moredeveloped countries.
The more- developed countries in Europe
and North America will have growth rates less
than 1% . Some countries such as Russia,
Germany, Italy, and Japan will even
experience negative growth rates.
Fertility Rates
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Replacement level fertility (RLF) is the level of fertility
at which has only enough children to replace
themselves, or about 2 children per couple.
It takes RLF of 2.1 to replace each generation since
some children will die before they grow up to have
their own two children.
RLF rates are lower in moderately developed
countries (MDC) and higher in less-developed
countries (LDC) due to higher infant mortality rates in
LDC.
The total fertility rate (TFR) is the average number of
children that each woman will have during her
lifetime.
Cont. Fertility Rates
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The world’s population is still growing quickly. This growth is due
to nations with above-replacement TFRs and a population
momentum caused by large numbers of younger females who
have as yet not had children.
Declines in fertility rates can be attributed to several factors.
Urbanization results in a higher cost of living. Urbanization
reduces the need for extra children to work on farms.
There is a greater personal acceptance and government
encouragement of contraception and abortion. The numbers
of females in the workforce and female educational
opportunities are increasing. More individuals desire to increase
their standard living by having less children.
The two main effects of TFRs less than 2.1 without additions
through immigration are population decline and population
aging.
Growth Models
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There are Two reproductive strategies:
r-selected species: have adaptations that
permit them to rapidly increasing their numbers
and they tend to be below their carry capacity
for long periods- but have potential to
overshoot.
K-selected species: have adaptations that
permit them to live in a state of equilibrium and
they are close to their carrying capacity.
Type I- K-selected species that have high
survival rates throughout most of their lifespan.
As they approach old age, they die in large
numbers
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Type II- relatively constant decline in
survivorship throughout their lifespan
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Type III- r-selected species experience low
survivorship early in life; few reach adulthood
Exponential Growth “ J- Curve”- is growth at a
constant rate
Logistic Growth “ S- Curve” this reaches its carrying capacity
Surviorship Growth- is a graph showing the
number or proportion of individuals surviving at
each age for a given species or group
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Exponential, Logistic, and
Survivorship Models
Demographic Transition
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Demographic Transition- refers to the
transition from high birth and death
rates to low birth and death rates as a
country develops from a pre-industrial
to an industrialized economic system.
Or is a model that describes population
change over time.
There are 4 stages:
Stage 1: Pre modern- is associated with
pre modern times, and is characterized
by a balance between birth rates and
death rates.
Stage 2: Urbanizing/Industrializing- sees
a rise in population caused by a
decline in the death rate while birth
rate remains high, or perhaps even rises
slightly.
Stage 3: Mature Industrial – moves the
population towards stability through a
decline in one birth rate.
Stage 4: Post Industrial – is
characterized by stability in this stage
the population age structure has
become older.
Age- Structure Diagrams
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A good indicator of future trends
in population growth is furnished
by age-structure diagrams. Age
structure diagrams are
determined by birth rate,
generation time, death rate, and
sex ratios.
When the Base is large ( greater
number of individuals in the
population), there is a potential
for an increase in the population
as these younger individuals
mature and have children of
their own (population
momentum).
When the top of the pyramid is
larger, it indicates a large
segment of the population is past
their reproductive years and
indicates a future slowdown in
population growth.
 Age
structure Diagrams
Helpful Website Links
 http://www.marathon.uwc.edu/geograp
hy/demotrans/demtran.htm
 http://www.geography.learnontheinterne
t.co.uk/topics/popn1.html
 http://en.wikipedia.org/wiki/Population
 http://en.wikipedia.org/wiki/Survivorship_c
urve
Video link
 http://www.gamequarium.org/cgi-
bin/search/linfo.cgi?id=16214
 http://www.gamequarium.org/cgi-
bin/search/linfo.cgi?id=16214
Questions
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What is the population growth rate for the United
States? ( Look at Formula and example at
beginning)
In your own words what does Demographic
Transition mean? And List and explain the 4 stages?
What does Replacement Fertility and Total Fertility
Rate mean? What are the two main Effects of TFRs?
Explain what the Age- Structure Diagram shows.
The Two reproductive strategies are? And what do
they mean?
What are the Three Growth Models and in your own
words explain what they mean? List the types and if
its k- selected or r-selected?