Exploring spatial variation in fish and aquatic ecosystem responses to wildfire in the Pacific Northwest
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Recent shifts in wildfire regimes have increased interest in spatially explicit models and indices that characterize the risks that wildfires pose to fish and aquatic ecosystems. These models are of interest to both resource managers and scientists to aid in the development of testable hypotheses and guide resource management decisions. However, there is substantial uncertainty about wildfire risk to fish and aquatic ecosystems and how ecosystem responses vary spatially across different regions. Here, we applied a dynamic food web simulation model to explore how variation in stream temperature can influence fish and aquatic ecosystem responses to wildfire in the Pacific Northwest. In the model, we conducted a sensitivity analysis where we varied background stream thermal conditions that may contribute spatial heterogeneity to fish responses to wildfire. We then used outputs from model simulations to identify potential ecological thresholds of stream temperature that may be stressful for fish if wildfires occur. Ecological thresholds identified by the model could then be linked to maps of stream temperature conditions across the Pacific Northwest to identify regions where fish may be more likely to be resilient to fire versus regions of potential vulnerability. Collectively, model simulations seek to explore the extent to which fire effects on aquatic ecosystems are likely to vary according to the ecological context of where a fire takes place. As a result, insights as provided by these model simulations can act as conceptual models which can be used to improve understanding, generate new hypotheses, and inform wildfire risk assessments for the region.