Geoscience Reference
In-Depth Information
house et al. 1984). Detailed courtroom testimony in trials related to lawsuits
over management of the northern spotted owl (
Strix occidentalis caurina
) was
ignored in the decision by Judge Helen Frye because she did not understand
the models. Models presented by scientists are often viewed as a smokescreen
by decision makers who fail to understand the complexities of the mathemat-
ics or computer code (Boyce 1992a). Most of these problems can be overcome
by careful attention to producing models that are accessible to managers and
other people who might be able to benefit from the models.
In 1988 I was asked to develop a model for wolf recovery in the greater Yel-
lowstone ecosystem. I made three trips to Yellowstone National Park before
developing my model with the express purpose of trying to understand how
the model would be put to use. No one seemed to have a clear picture of why
the government had asked for a model, other than hoping that it would give
them some insight into the possible consequences of wolf recovery to ungulate
populations in the greater Yellowstone area. I decided that the most useful
model would be one that would help to educate the managers and interested
public about predator-prey dynamics. Interface between the model and the
user was crucial to how well the model would be received. I programmed a
model that was user friendly and simple enough that almost anyone could use
it (Boyce 1993). I learned through experience that giving careful attention to
presentation is much more time-consuming and tedious than the modeling
itself.
It was clear to me that the Yellowstone ungulate populations fluctuate sub-
stantially among years depending on winter severity. It was also clear that I was
dealing with considerable uncertainty in my estimates of functional responses
because I had meager data on wolf predation on elk. So uncertainty was a
major issue that would shape my model. I confronted this issue in part by
building a stochastic model that never gave the same result twice.
Another major source of uncertainty was anticipating how the wolves
would be managed once they were introduced. Indeed, how the wolves would
be managed was a current issue of debate in the process of developing a plan
for the reintroduction. I confronted this problem by allowing the user of the
model to choose how he or she would manage the wolves given the chance.
This helped build confidence in the model because the user was helping to
parameterize the model and thereby had more confidence in the results. User
inputs were kept simple and the actual consequences of user-defined manage-
ment decisions were transparent only to those who wanted to read the pro-
gram code.
I believe that the model was successful in accomplishing my objectives, and
