Post-fire surface fuel dynamics in California forests across three burn severity classes

Abstract

Forest wildfires consume fuel and are followed by post-fire fuel accumulation. This study examines post-fire surface fuel dynamics over 9 years across a wide range of conditions characteristic of California fires in dry conifer and hardwood forests. We estimated post-fire surface fuel loadings (Mgha−1) from 191 repeatedly measured United States national inventory plots in dry conifer and hardwood stands of 49 California forest wildfires and identified differences across fire severity classes – low, moderate and high. No significant change in duff load was detected within the first 9 years post-fire across all forest types and fire severities. Litter, 1-h and 10-h fuels exhibited a quadratic trend over time in dry conifer stands, peaking ~6 years after fire, whereas hardwood stands displayed a constant rate of increase in those fuel types. For 100- and 1000-h fuels, the annual rate of change was constant for dry conifer and hardwood stands with differing rates of change across fire severity classes. This study was based on an extensive, spatially balanced sample across burned dry conifer and hardwood forests of California. Therefore, the estimated patterns of fuel accumulation are generally applicable to wildfires within this population.