Charles H. Luce

Parameter identification for a runoff model for forest roads

Rainfall simulation is a commonly used approach for studying runoff and erosion from forest roads, and a method is needed to estimate infiltration parameters from these experiments. We used two algorithms, the Simplex and Shuffled Complex Evolution, to estimate parameters for a physically based infiltration and overland flow model. Each algorithm was tested by estimating parameters for 92 field-measured hydrographs from forest roads. Nine of the field-measured hydrographs allowed us to further test whether estimated parameters could be extended to other antecedent conditions and plot sizes. The results demonstrate (1) the physically based model is able to estimate hydrographs from forest roads, (2) the two algorithms find unique parameter sets in spite of an error surface that suggests identifiability problems between the hydraulic conductivity and pressure parameters, (3) the two algorithms converged to the same parameter values, and (4) that parameters estimated for one antecedent condition and plot size can be extended to others with reasonably small error.

Climate change, forests, fire, water, and fish: Building resilient landscapes, streams, and managers

Fire will play an important role in shaping forest and stream ecosystems as the climate changes. Historic observations show increased dryness accompanying more widespread fire and forest die-off. These events punctuate gradual changes to ecosystems and sometimes generate stepwise changes in ecosystems. Climate vulnerability assessments need to account for fire in their calculus. The biophysical template of forest and stream ecosystems determines much of their response to fire. This report describes the framework of how fire and climate change work together to affect forest and fish communities. Learning how to adapt will come from testing, probing, and pushing that framework and then proposing new ideas. The western U.S. defies generalizations, and much learning must necessarily be local in implication. This report serves as a scaffold for that learning. It comprises three primary chapters on physical processes, biological interactions, and management decisions, accompanied by a special section with separately authored papers addressing interactions of fish populations with wildfire. Any one of these documents could stand on its own. Taken together, they serve as a useful reference with varying levels of detail for land managers and resource specialists. Readers looking for an executive summary are directed to the sections titled “Introduction” and “Next Steps.”