Drivers of fire severity in repeat fires: Implications for mixed-conifer forests in the Sierra Nevada, CA

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Across plots that burned in multiple low- to moderate-severity fires, our findings indicated that post-fire outcomes in these systems are variable, resulting in a range of structural conditions following a first reburn (i.e., second fire). Areas with high levels of dead biomass burned at significantly higher severity in the third fire compared to those with higher shrub cover. Following a second fire, many plots exceeded historical estimates of stand structure metrics for yellow pine and mixed-conifer forests of the Sierra Nevada, particularly for coarse woody debris load, with some plots exceeding historical natural range of variation (NRV) estimates for live tree density. In plots with a history of varying fire severity in the initial and second fires, we found that snag basal area was associated with higher fire severity in the third fire.