Question

Problem 1

Using fire in forest management sounds contradictory. Prescribed fire, however, is an important tool for foresters, and a recent article describes how decision analysis is used to decide when, where and what to burn. In one example, a number of areas in the Tahoe National Forest in California had been logged and were being prepared for replanting. Preparation included prescribed burning, and twopossible treatments were available: burning the slash as it lay on the ground, or “yarding of unmerchantable material” (YUM) prior to burning. The latter treatment involves using heavy equipment to pile the slash. YUM reduces the difficulty of controlling the burn but costs an additional $100 per acre. In deciding between the two treatments, two uncertainties were considered critical. The first was how the fire would behave under each scenario. For example, the fire could be fully successful, problems could arise which could be controlled eventually, or the fire could escape, entailing considerable losses. Second, if problems developed, they could result in high, low, or medium costs.

a. What do you think the US Forest Service’s objectives should be in this decision? In thearticle, only one objective was considered, minimizing cost (including costs associated with an escaped fire and the damage it might do). Do you think this is a reasonable criterion for the Forest Service to use? Why or why not?

b. Develop an influence diagram for this situation.

Answer 1

a. The article talks about 2 possible treatment methods that can be used. Either burning the slash as it lay on the ground, or “yarding of unmerchantable material” (YUM) prior to burning which involves using heavy equipment to pile the slash. There are advantages in following the second method as the fire can be concentrated to a particular location and is more controlled. The uncertainty here is that they do not know how the fire would behave under each situation, and for that the department can take small patches of land and try out the method there. This would give them an idea as to how the fire would behave under different scenarios.

Another concern is the cost factor which is a very important point as YUM would incur an additional $100 per acre. US Forest Service’s objectives should hence consider different factors while taking decisions, cost being one factor and safety of wildlife and human beings being the next. I do find considering cost a reasonable decision as long as there are other parameters being considered by the department.

b.