Using field data to assess model predictions of surface and ground fuel consumption by wildfire in coniferous forests of California

Abstract

Inventories of greenhouse gas (GHG) emissions from wildfire provide essential information to the state of California, USA, and other governments that have enacted emission reductions. Wildfires can release a substantial amount of GHGs and other compounds to the atmosphere, so recent increases in fire activity may be increasing GHG emissions. Quantifying wildfire emissions however can be difficult due to inherent variability in fuel loads and consumption and a lack of field data of fuel consumption by wildfire. We compare a unique set of fuel data collected immediately before and after six wildfires in coniferous forests of California to fuel consumption predictions of the first-order fire effects model (FOFEM), based on two different available fuel characterizations. We found strong regional differences in the performance of different fuel characterizations, with FOFEM overestimating the fuel consumption to a greater extent in the Klamath Mountains than in the Sierra Nevada. Inaccurate fuel load inputs caused the largest differences between predicted and observed fuel consumption. Fuel classifications tended to overestimate duff load and underestimate litter load, leading to differences in predicted emissions for some pollutants. When considering total ground and surface fuels, modeled consumption was fairly accurate on average, although the range of error in estimates of plot level consumption was very large. These results highlight the importance of fuel load input to the accuracy of modeled fuel consumption and GHG emissions from wildfires in coniferous forests.

Investigation of the Fire Radiative Energy Biomass Combustion Coefficient: A Comparison of Polar and Geostationary Satellite Retrievals Over the Conterminous United States

“…For the largest Wallow fire, the biomass consumption per unit area was 3.02 kg/m 2 (Figure ), which differs by only 4% from the biomass consumption estimated using the Consume 3.0 FC model (Veraverbeke & Hook, ). The results illustrated in Figure are comparable in magnitude with biomass consumption estimates across the CONUS for different fires and years (where fuel conditions and fire behavior differences mean that exact quantitative comparison is not meaningful; Lydersen et al, ; Prichard et al, ; Yokelson et al, ).…”

“…For the largest Wallow fire, the biomass consumption per unit area was 3.02 kg/m 2 ( Figure 5), which differs by only 4% from the biomass consumption estimated using the Consume 3.0 FC model (Veraverbeke & Hook, 2013). The results illustrated in Figure 5 are comparable in magnitude with biomass consumption estimates across the CONUS for different fires and years (where fuel conditions and fire behavior differences mean that exact quantitative comparison is not meaningful; Lydersen et al, 2014;Prichard et al, 2017;Yokelson et al, 2013). Figure 6 illustrates a comparison of the biomass consumption estimated by the bottom-up method based on the burn severity parameterized CC approach with the same approach but assuming CC = 0.5 ( Figure 6a) and with the IPCC FC method (Figure 6b).…”

Sensitivity of Simulated Fire‐Generated Circulations to Fuel Characteristics During Large Wildfires

“…Similarly, Lydersen et al. (2014) document total fuel consumption of ∼14 kg m −2 (140 Mg ha −1 ) in the Northern Sierra, with significant contribution from duff layers and forest litter. Large fuel consumption is also observed in other forested environments in the western US, for example, McCarley et al.…”

“…To be specific, Cansler et al (2019) found an average total fuel consumption of 15.1 kg m 2 (151 Mg ha 1 ) during the 2013 Rim Fire in Yosemite National Park. Similarly, Lydersen et al (2014) document total fuel consumption of ∼14 kg m 2 (140 Mg ha 1 ) in the Northern Sierra, with significant contribution from duff layers and forest litter. Large fuel consumption is also observed in other forested environments in the western US, for example, McCarley et al (2020) showed airborne laser scanning estimated fuel consumption in large wildfires exceeding 20 kg m 2 (200 Mg ha 1 ) over large areal expanses.…”

Heading and backing fire behaviours mediate the influence of fuels on wildfire energy

“…Additionally, incomplete combustion of at least one of the two litter and duff strata occurred in 74 plots (66%), with incomplete combustion of both litter and duff occurring in 44 (39%) of the 112 plots. Currently, fire consumption models such as BURNUP or FOFEM often assume high or complete combustion of litter and duff in wildfires (Lydersen et al 2014;Lutes 2020) and may therefore overestimate wildfire emissions.…”