Exercise 1
1. Scenario 1: Approx 5 million trees are found in Namanve forest.
A Construction Company has been cutting down approx. 100,000
trees every year. A concerned environmental group has been able
to plant approx. 7,500 tree every three months for the fist half
of the year, then the second half of the year the number
increased to 12,000 trees every two months.
How many trees will be in Namanve forest in thirty years?
2. Scenario 2: Currently Uganda has a population of 38 million
people. She has one of the fast growing population with a
birthrate of 3% per annum. The following are responsible for the
deaths: disease (5%), accidents (0.5%) and old age (1%) of the
population every six months. Currently Uganda receives about
10,000 migrants from Sudan and Congo every 4 months.
(a)
Clearly define the variables and the units. Write
Equations for the model.
(b)
Draw independent STELA Models for
i. Population growth
ii.
Population decline
Hint:In both cases use the factors given
(c)
Use STELLA software to build a simulation model for
the population and explain the behavior of the population
from the graph. What will Uganda’s population be like at
the end of 10 years?