An Individual-Based Model of Swan–Macrophyte Conflicts on a Chalk River - River Conservation and Management - page 321

Figure 27.2 Sensitivity of the four model predictions to a 25% increase and decrease in the value of each parameter.
* indicates analyses not possible because swans moved out of the study area immediately.

Discussion

the number of swan days that the study section of
river could support and also overestimated the time
swans spent feeding.
The depletion of Ranunculus represents a
substantial loss of chalk river habitat complexity
(O'Hare et al. , 2007), indicating that management
action is required to reduce the impact on
conservation and fisheries interests. The model
predictions, albeit for a relatively short stretch
of river and adjacent pasture land, illustrate the
potential application of IBMs to assess both the

This study builds on previous work by O'Hare
et al . (2007) and improves it by replacing a
simple 'resource-consumer' model with a more
realistic individual-based (IBM) one. For the River
Frome the IBM predictions of macrophyte biomass
depletion, number of swan days supported by
the study area, feeding patch use and the time
swans spend feeding were generally similar to field
observations. However, the model underestimated