Modeling the effects of wildfire on aquatic ecosystems in the Pacific Northwest

Wildfires are widespread disturbances that influence the structure of ecosystems in the forested landscapes of the western United States. After decades of natural resource policies that suppressed fire activity on the landscape, changes in climate and forest conditions are increasing the occurrence of large, high severity fires. Fires can have complex effects on aquatic ecosystems—affecting aquatic systems through a variety of physical and ecological processes and pathways. While previous research has evaluated the effects of fire largely via field-based observational studies, these empirical studies are often limited in the inferential ability to tease apart complex mechanisms and extrapolate findings across broader spatial extents. Here, we present two modeling efforts to help us better understand the complex effects of fire on aquatic ecosystems. First, we apply the Aquatic Trophic Productivity model—a food web system dynamics model—to provide a mechanistic, process-based approach to synthesize the multiple pathways by which fires can affect aquatic ecosystems. Second, we develop spatial analyses of wildfire risk to identify the relative vulnerability and resilience of watersheds across the Pacific Northwest. Taken together, these modeling platforms will contribute an improved understanding of the effects of fire on aquatic ecosystems that can help to develop new conceptual models, direct future empirical studies as well as guide management actions.

Impact/Purpose

Wildfires, and their effects on human property, watersheds, and ecosystem values are a growing concern in the Western US.  Wildfires and associated responses can negatively affect water quality through increased loadings of sediment, introduction of toxic chemicals, and changes to how water is stored and routed through watersheds.  But wildfires can also help create conditions that provide long-term benefits to aquatic ecosystem condition, by creating stream habitats that support desired functions for fish, wildlife, and water quality. In this presentation we will present approaches for characterizing differing ways in which wildfires can influence water quality and aquatic habitat. This research is part of a larger effort intended to help managers identify best practices for protecting and restoring aquatic habitats and water quality.

Citation

Roon, D., K. Bladon, R. Flitcroft, AND Joe Ebersole. Modeling the effects of wildfire on aquatic ecosystems in the Pacific Northwest. Annual Meeting of the Oregon Chapter American Fisheries Society, NA, OR, March 02 - 04, 2022.