Post-fire management regimes affect carbon sequestration and storage in a Sierra Nevada mixed conifer forest

Forests mitigate climate change by sequestering CO2 from the atmosphere and accumulating it in biomass storage pools. However, in dry conifer forests, fire occasionally returns large quantities of CO2 to the atmosphere. Both the total amount of carbon stored and its susceptibility to loss may be altered by post-fire land management strategies. Forest managers face a great challenge when asked to manage these lands for C sequestration and simultaneously reduce fire hazard. The objective of our study was to understand how differing post-fire management strategies affect C sequestration and the size of storage pools in the 10 years after a wildfire in a Sierra Nevada mixed-conifer forest. Post-fire management regimes included: (1) salvage-logged, planted, and intensively managed plantation (IM); (2) salvage-logged and planted (SP); (3) no salvage (NS); and (4) green canopy (GC), where fire burned through, but 95% of the overstory trees survived. Carbon sequestration and storage were estimated from measurements of individual ecosystem carbon pools. These pools included: aboveground trees, saplings, snags, stumps, and understory, coarse wood and fine wood, duff, and soil. We found total ecosystem carbon storage was 282 +/- 15 Mg ha(-1) of C in the NS treatment, 206 +/- 31 Mg ha(-1) in the GC, 137 +/- 13 Mg ha(-1) in the SP, and 101 +/- 15 Mg ha(-1) in the IM treatment. There were no significant treatment differences in C storage among the pools that would constitute labile/fine fuels, but there were differences in recalcitrant (coarse fuel) C pools. The greatest C storage in recalcitrant C pools was 258 +/- 10 Mg ha(-1) in the NS and 197 +/- 30 Mg ha(-1) in the GC treatments. Post-fire carbon sequestration rates were 1.6 +/- 0.7 Mg ha(-1) - year(-1) of C in the GC, 0.7 +/- 0.3 Mg ha(-1) year(-1) in the SP, 0.5 +/- 0.1 Mg ha(-1) year(-1) in the NS, and 0.5 +/- 0.1 Mg ha(-1) year(-1) in the IM treatments, but these differences were not statistically significant. Tree carbon sequestration rates were highest in the GC treatment and lowest in the NS treatment. Overall, our results suggest that a mature green-canopy stand provides most benefit in terms of C sequestration, wildfire resilience, and other ecosystem services at a point 10 years after severe wildfire. For forests that suffer high fire mortality, unsalvaged (NS) stands will retain the most carbon onsite. Published by Elsevier B.V.