Joint Fire Science Program Project JFSP 14-1-01-2.
Climate change in the western United States has increased the frequency of extreme ﬁre weather events and is projected to increase the area burned by wildﬁre in the coming decades. This changing ﬁre regime, coupled with increased high-severity ﬁre risk from a legacy of ﬁre exclusion, could destabilize forest carbon (C), decrease net ecosystem exchange (NEE), and consequently reduce the ability of forests to regulate climate through C sequestration. While management options for minimizing the risk of high-severity ﬁre exist, little is known about the longer-term carbon consequences of these actions in the context of continued extreme ﬁre weather events. Our goal was to compare the impacts of extreme wildﬁre events on carbon stocks and ﬂuxes in a watershed in the Sierra National Forest. We ran simulations to model wildﬁre under contemporary and extreme ﬁre weather conditions, and test how three management scenarios (no-management, thin-only, thin and maintenance burning) inﬂuence ﬁre severity, forest C stocks and ﬂuxes, and wildﬁre C emissions. We found that the effects of treatment on wildﬁre under contemporary ﬁre weather were minimal, and management conferred neither signiﬁcant reduction in ﬁre severity nor increases in C stocks. However, under extreme ﬁre weather, the thin and maintenance burning scenario decreased mean ﬁre severity by 25%, showed signiﬁcantly greater C stability, and unlike the no-management and thin-only management options, the thin and maintenance burning scenario showed no decrease in NEE relative to the contemporary ﬁre weather scenarios. Further, under extreme ﬁre weather conditions, wildﬁre C emissions were lowest in the thin and maintenance burning scenario, (reduction of 13.7 Mg C/ha over the simulation period) even when taking into account the C costs associated with prescribed burning. Including prescribed burning in thinning operations may be critical to maintaining C stocks and reducing C emissions in the future where extreme ﬁre weather events are more frequent.
Krofcheck, D. J., M. D. Hurteau, R. M. Scheller, and E. L. Loudermilk. 2017. Restoring surface ﬁre stabilizesforest carbon under extreme ﬁre weather in the Sierra Nevada. Ecosphere 8(1):e01663. 10.1002/ecs2.1663