HR: 08:45h
AN: NB21G-02 INVITED     [Abstracts]
TI: Searching for an Integrated Watershed Salmonid Population Model
AU: * Ligon, F K
EM: frank@stillwatersci.com
AF: Stillwater Sciences, 850 G Street #K, Arcata, CA 95521 United States
AU: Dietrich, W E
EM: bill@geomorph.berkeley.edu
AF: University of California at Berkeley, 301 McCone Hall , Berkeley, CA 94720 United States
AB: In proposing to restore a stream or watershed, we imply that we know what we are restoring and why. However, in many cases, restoration proceeds without having the tools to adequately assess the efficacy of a project-both in terms of its likely local success and what effects it may have at a larger watershed or regional scale. In salmonid ecology and restoration, our approach has been to "step back" and investigate the degree to which geology, tectonics, and climate determine the relative abundance and temporal variability of the species present in a watershed or reach. In other words, does the habitat provided by a landscape prior to European disturbance (the so-called historical reference condition) allow us to predict, using salmon life history theory, the historical population dynamics of all salmonid species for a watershed or region? Likewise, as changes in physical processes have occurred due to human disturbance, can we predict the differential effects on the abundance of different salmonid species historically present in the watershed? To explore these questions, we have developed the "reference model". The reference model is based on a set of desktop watershed analyses tools that estimate a number of landscape attributes including channel slope, drainage area, stream temperature, and shallow landslide sensitivity. The model uses these tools to predict the spatial distribution of habitat and its quality and quantity. Then, by relating the habitat to life stage specific survival, the model predicts population dynamics under reference and current conditions, and under proposed restoration scenarios. In applying the reference model, we explicitly link salmon restoration targets and plans to an understanding of the role of physical processes on the historical and current population dynamics. As is true with most models, the reference model's predictions have the greatest value when they can be treated as testable hypotheses. Ongoing restoration projects that demonstrate the model and explicitly test model predictions will be presented.
DE: 1803 Anthropogenic effects
DE: 1824 Geomorphology (1625)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly