Chap5_Dear dieout

Question 1

The model represents a deer population which is assumed to have become infertile. In other words, no new deer are being born, but deaths occur as usual. The population’s age structure is neglected. What kind of population change is observed, what kind of feedback system ?

Answer 1

This Model is a very simplistic animal population dieout model. It serves to illustrate Exponential Decay as a very important elementary decay process and example for a negative feedback system

Question 2

Draw the CLD and determine the type of feedback.

Answer 2

The causal loop diagram clearly shows a negative feedback loop containing the variables Deer (representing the amount of animals) and Deaths (representing the number of new-dead deer during one unit of time). Death Rate is NOT part of any feedback loop

Question 3

Draw the Stock N Flow, define the variables!

Answer 3

• Deer (variable type: stock, unit: Animals, initial value: 1000 Animals)
• Deaths (variable type: flow, unit Animals/year)
• Death Rate (variable type: auxiliary, unit: 1/year)

Question 4

If death rate is set to 0.3/ year what does this mean ?

Answer 4

Set Death Rate = 0.3/year (probability of dying for one animal is 30% year; the average lifetime of one animal is 1/0.3 years = 3.33… years).

Question 5

Changing initial Population and rate of death