Effects of forest fuel reduction on fire severity and long-term carbon dynamics across three Pacific Northwest ecosystems

Two forest management strategies that are being debated in the context of federally managed landscapes in the US Pacific Northwest involve a perceived trade-off between fire restoration and carbon sequestration. The former strategy would reduce fuel (and therefore carbon) that have accumulated through a century of fire suppression and exclusion, leading to extreme fire risk in some areas. The latter strategy would manage forests for enhanced carbon sequestration as a method of reducing atmospheric CO₂ and associated threats from global climate change. This study examines the trade-off between these two strategies by employing a forest ecosystem simulation model, STANDCARB, to simulate the effects of fuel reduction on fire severity and the resulting long-term carbon dynamics among three ecosystems. We simulated the effects of six different fuel reduction treatments on fire severity and stand-level carbon dynamics for forest ecosystems of the eastern and western Cascade Range of Oregon, as well as Oregon’s Coast Range. Results demonstrate that certain fuel reduction treatments can be successful in reducing fire severity, but the amount of fuel removal required to reduce fire severity almost always exceeds the amount of carbon lost in an untreated stand subject to a fire of higher severity. This suggests that forest management plans aimed solely at maximizing long-term carbon storage in these ecosystems should forego fuel reduction treatments, though utilizing harvested forest fuels as biofuels could serve as a substitute for fossil fuels and make a contribution toward the amelioration of atmospheric CO₂.