Fire Intensity in the Idaho Salmon River Watershed Across Time and Ecoregions

With modern fire suppression strategies and the onset of anthropogenic climate change, it is known that fire regimes have shifted to less frequent, but more intense wildfires in the Western United States. Many studies have been conducted on this phenomenon and its effects on fire ecology. Yet, not much research has been done on the trends of specific ecoregions, especially ones distinct to single states. This research paper investigates wildfire trends in the Salmon River Watershed in Idaho. Based on previous research, we hypothesized that fire intensity would show an increase while fire frequency would show a decrease in all ecoregions. Using Idaho’s distinct ecoregions, we established burn regions from which we collected wildfire data, including area burned and frequency of fires per year from 1985 to 2023. For fire frequency, we found that no burn regions showed a statistically significant change. For fire intensity, we found that only two burn regions, the Alpine Zone/Subalpine Zone/Barren Mountains and the Dry Partly Wooded Mountains, showed a statistically significant increase in fire intensity. We determined that the first burn region historically had relatively no fire regimes compared to other regions, while the second is undergoing substantial anthropogenic change, which contributed to their significant increase in fire intensity. No significant difference was found in the frequency or the intensity of the remaining burn regions. This may stem from limited data and a smaller scale time frame and study area. These results can be used to determine what characteristics of an ecoregion contribute to increasing wildfire intensity and make way for future fire ecology research to focus on smaller scale study areas to determine specific fire management strategies.