PARENT SESSION
Oral Session #85: Ecosystem Restoration in the Grand Canyon.
Presiding: S. Gloss and B. Gold
Thursday, August 8. 1:00 PM to 3:45 PM. Mohave Meeting Room, TCC.
Using ecosystem models to screen policy options for Grand Canyon restoration.
WALTERS, CARL*,1, KORMAN, JOSH2, 1 UNIVERISTY OF BRITISH COLUMBIA, VANCOUVER, BC, CANADA2 ECOMETRIC RESEARCH, VANCOUVER, BC, CANADA
ABSTRACT- Adaptive Environmental Assessment and Management workshops have been used over the past five years to involve a wide range of scientists in development of a complex ecosystem model for the Grand Canyon aquatic and riparian ecosystem. This model represents the spatial organization of production processes in relation to water management policies (seasonal, diurnal flow regimes, temperature) both longitudinally (from Lake Powell to Lake Mead) and horizontally (from the river bottom to the top of the riparian zone). Production processes are linked to a set of detailed population models for key species of management and endangered species concern. The model has been used not to make precise predictions, but rather to compare and "screen" water management options in hopes of at least excluding options that have been suggested on the basis of simplistic ecological reasoning and could not possibly work. The main uncertainty revealed in these simulations has been about the responses of exotic animals and plants to habitat restoration measures for native species: It is quite possible that exotics will benefit from the measures enough to cause net deleterious effects on native species through trophic interactions (predation, competition). Further, we have found that existing monitoring programs are likely inadequate to detect policy failure in a timely way, given trends and variability already occurring in the system. There is a critical need to design long-term management experiments that test policy options through repeated, contrasting applications of treatment alternatives.
KEY WORDS: Adaptive Management, Conceptual Modeling, Complex Systems, Rivers