Logistic population growth: The graph in Figure 1.38 shows the population N = N (d ), in thousands of animals, of a particular species on a protected reserve as a function of the date d. Ecologists refer to growth of the type shown here as logistic population growth.
a. Explain in general terms how the population N changes with time.
b. When did the population reach 80 thousand?
c. Your answer in part b is the solution of an equation involving N (d ). Which equation?
d. During which period is the graph concave up? Explain what this means about population growth during this period.
e. During which period is the graph concave down? Explain what this means about population growth during this period.
f. When does a point of inflection occur on the graph? Explain how this point may be interpreted in terms of the growth rate.
g. What is the environmental carrying capacity of this reserve for this species of animal? That is, what is the maximum number of individuals that the environment can support?
h. Make a new graph of N (d ) under the following new scenario. The population grew as in Figure 1.38 until 1990, when a natural disaster caused half of the population to die. After that the population resumed logistic growth.