Temporal fuel dynamics following high-severity fire in dry mixed conifer forests of the eastern Cascades, Oregon, USA

Fire-resilient landscapes require the recurrent use of fire, but successful use of fire in previously burned areas must account for temporal fuel dynamics. We analysed factors influencing temporal fuel dynamics across a 24-year spatial chronosequence of unmanipulated dry mixed conifer forests following high-severity fire. Duff and litter accumulated as bark sloughed from snags and leaves senesced from recovering vegetation, averaging 14.6 Mg ha^–1 and 22.1 Mg ha^–1 at our 24-year post-fire site, respectively. 1-h fuels increased linearly, averaging 1.1 Mg ha^–1 at our 24-year post-fire site, with additions occurring from recovering vegetation. 10-h and 100-h fuels exhibited non-linear temporal trends, with maximum loadings occurring 14 years (3.9 Mg ha^–1) and 18 years (10.5 Mg ha^–1) post-fire, respectively. 1000-h fuel accumulation slowed after 20 years post-fire (reached 124.6 Mg ha^–1), concurrently with ~90% snag fall and fragmentation. Maximum herbaceous fuel loading averaged 0.73 Mg ha^–1 at our 5-year post-fire sites, but only averaged 0.02 Mg ha^–1 at all sites thereafter. Live shrub biomass accumulation slowed after 21 years post-fire, averaging 14.3 Mg ha^–1 at our 24-year post-fire site. Managers can use post-fire temporal fuel dynamics to help facilitate the restoration of fire regimes while mitigating undesirable fire effects.