Population Growth
Ecology CFU#1
Lesson #3
SWBAT how birth/death rates
affect population size.
• You will create a graph representing
human population growth and use it to
predict future growth.
• We will analyze the reasons behind this
population growth and relate it to ecology
concepts such as birth/date rates,
population density, and limiting factors.
• We will add important population
vocabulary to your notes.
Setting Up Your Graph…
• Your graph should be a full page in size.
• Give your graph a title.
• Time is the manipulated variable. Place it on the
X (horizontal axis.) Values should range from
1650 to 2020, using a constant increment.
• Population is the responding variable. Place it
on the Y (vertical axis.) Values should range
from 0-20 billion, using a constant increment.
Plotting the data…
Year A.D.
Number of
People
(Billions)
1650
0.5
1750
0.7
1850
1.0
1925
2.0
1956
2.5
1966
3.3
1970
3.6
1974
3.9
1976
4.0
1980
4.4
1991
5.5
2000
6.0
2004
6.4
2012
7
Graph
Population (In Billions)
World Population Growth
20
18
16
14
12
10
8
6
4
2
0
1650
1700
1750
1800
1850
Year (A.D)
1900
1950
2000
2050
Analysis Questions
(Please answer on the back of your graph)
• 1.) It took 1649 years for the world population to
double, going from 0.25 billion people to 0.5
billion people How long did it take for the
population to double once again?
• 2.) How long did it take for the population to
double a second time? A third time?
• 3.) Based on your graph, in what year will the
population reach 8 billion?
• 4.) Using prior knowledge, what factors have
contributed to the world’s overall population
growth in the last 150 years?
Analysis Answers
• 1. It took 200 years for the population to double
from 0.5 to 1.0 billion (16501850)
• 2. It took 75 years to double from 1 to 2 billion
(18501925) and 51 years to double from 2 to 4
billion (19251971)
• 3. (Answers will vary, but most estimates are
around 2027)
• 4. Agricultural revolution resulted in greater
growth and transport of food reduced death from
starvation. Advances in medicine, sanitation and
nutrition reduced death from disease.
In your notes…
Population Notes
• Birth rate- the number of births in a population
in a certain amount of time.
• Death rate- the number of deaths in a
population in a certain amount of time.
• Population Statement
– If birth rate > death rate, populations increase
– If death rate > birth rate, populations decrease
• Population Density
– Number of individuals ÷ Unit area
– Example: 20 monarch butterflies in 10m2 area =
20/10 = population density of 2 monarchs per square
meter
Population Notes
• A limiting factor is an environmental
factor that causes a population to
decrease.
• Some limiting factors for populations are
– food & water
– Space weather conditions.
• Carrying capacity- the largest population
that an area can support.
Birth Rates…
Population Density
Population Density
•
Map showing urban areas with at least one million inhabitants in 2006. Only
3% of the world's population lived in cities in 1800; this proportion had risen
to 47% by the end of the twentieth century, and reached 50.5% by 2010