Comparing Modeled Emissions from Wildfire and Prescribed Burning of Post-Thinning Fuel: A Case Study of the 2016 Pioneer Fire

Abstract

Prescribed fire is often used by land managers as an effective means of implementing fuel treatments to achieve a variety of goals. Smoke generated from these activities can put them at odds with air quality regulations. We set out to characterize the emission tradeoff between wildfire and prescribed fire in activity fuels from thinning in a case study of mixed conifer forest within the Boise National Forest in central Idaho. Custom fuelbeds were developed using information from the forest and emissions were modeled and compared for four scenarios, as follows: Untreated fuels burned in wildfire (UNW), prescribed fire in activity fuels left from thinning (TRX), a wildfire ignited on the post-treatment landscape (PTW), and the combined emissions from TRX followed by PTW (COM). The modeled mean total emissions from TRX were approximately 5% lower, compared to UNW, and between 2–46% lower for individual pollutants. The modeled emissions from PTW were approximately 70% lower than UNW. For the COM scenario, emissions were not significantly different from the UNW scenario for any pollutants, but for CO2. However, for the COM scenario, cumulative emissions would have been comprised of two events occurring at separate times, each with lower emissions than if they occurred at once.

California Case Study of Wildfires and Prescribed Burns: PM2.5 Emissions, Concentrations, and Implications for Human Health

“…For the Rx scenarios, because fires occur on different days than for the wildfire scenario, there are different fuel moistures associated with the fires. Canopy consumption, a key difference between wildfires and prescribed burns, 26 was set at 50% for wildfires and 0% for prescribed burns, as recommended in BlueSky. For all scenarios, the percentage of shrub blackened was set to 50%, as recommended in BlueSky.…”