1. Interpreting the graphs
Population graphs
Interpreting the graphs

2. What is Carrying Capacity?
Carrying capacity is the number of individuals of a species that an ecosystem can support.

3. Pleasant Island Pheasants
Carrying Capacity
Growth rate = 0
Growth rate slows down
Pleasant Island Pheasants
1937 – 8 pheasants introduced
1945 – 1325 pheasants on island
1947 – 1600 pheasants on island

4. Why Did the Pheasant Population Stabilize?
Females were laying the same number of eggs
Death rate increased, number of surviving chicks decreased
Births > deaths pop. Up
Births < deaths pop. Down
Births = deaths zero population growth

5. Carrying Capacity
Maximum population size indefinitely supported by available resources
Determined by sustained availability of
renewable resources such as nutrients, water and light
space
Influenced by environmental resistance

6. A = lag phase (very few organisms to begin with – reproduction is slow
B = acceleration phase
C = exponential phase
F = population crash due to limited resources

7. Grand Canyon Kaibab Deer
1907 – 4000 deer on Kaibab Plateau
beginning in 1907– removal of predators
1924 – 100,000 deer
very severe winter in
1927 – 10,000 deer
removed 816 cougars
removed 30 wolves
removed 7,338 coyotes

8. What Were the Effects of the Deer Population at Its Peak?
Forest was over browsed leading to
Loss of ground cover
Soil compaction – less water and increased erosion
Carrying capacity reduced for years

9. Carrying capacity
1. What is the carrying capacity of the cockroach population?
2. At what day did the cockroach population meet the carrying capacity?

10. Carrying Capacity
Sometimes a best fit line is used to represent the carrying capacity.
3. What is the carrying capacity of this population?
4. At what year did it reach the carrying capacity?
5. Why did the population decrease in 1950?

11. Population Crash 6. What is happening between 1944-1960?
7. What do you think happened in 1963?

12. 8. Which letter points to the x axis?
9. Which letter points to the y axis?

13. The number of predators increased this year.
10. Which of the following best describes why the population of foxses declined at point A?
The number of predators increased this year.
Competition increased and foxes were limited by the number of rabbits available?
A natural disaster wiped out a large portion of the foxes
The rabbits were hibernating and there was less food available. A