Table 2.

Internal rates of return for selected treatment scenarios.

ScenarioReturn (%)
1.A single investment now of $10 per tree will eliminate annual costs of $6 for 10 years58.9
2.A single investment now of $20 per tree will eliminate annual costs of $6 for 10 years.27.0
3.A $20 investment every 10 years will eliminate annual costs of $6. (Note reducing cost by $6 per year is equivalent to eliminating an annual cost of $6.)27.0
4.A $10 investment now will eliminate a $30 cost in 5 years and an additional $30 cost in 10 years.30.4
5.A $20 investment now will eliminate a $30 cost in 5 years and an additional $30 cost in 10 years.17.1
6.When a period of 45 years is considered, a $100 investment per tree now will delay for 5 years a $300 cost normally occurring in 15 years, with additional $300 costs occurring every 8 or 9 years instead of every 5 years.10.2
7.Same as scenario 6 except that recurring costs are $400.11.9
8.Same as scenario 6 except that recurring costs are $500.13.3