Carbon storage in southern boreal forests following fire

Changes in carbon (C) after fire were measured in seven southern boreal upland forest stands during the five immediate post-fire years and 23 years after the fire. Pre-fire above-ground C mass of the stands was estimated. Combustion losses were 19% of the pre-fire above-ground C mass (8.4 kg m⁻²), and an additional 4% of that C mass was lost in the following 3–4 years. After 23 years, neither C mass of understory (0.1 kg m⁻²) nor standing snags (0.3 kg m⁻²) differed from that estimated before the fire; tree C was less (2.4 vs. 6.0 kg C m⁻²), and forest floor (2.5 vs. 1.4 kg C m⁻²) and coarse woody debris (1.7 vs. 0.7 kg C m⁻²) C were higher. Above-ground C mass was 84% of pre-fire mass. There were no measured changes in surface soil C following the fire (2.9 kg C m⁻²). Total C mass, including surface soil, was 10.2 kg m⁻² at 23 years or 91% of the estimated pre-fire C. Although gross fluxes of C followed the fire, massive net losses of C did not occur either immediately or in the two decades after fire. Dynamics of C differed among the stands. Data from either a single stand or a chronosequence in space can lead to different conclusions than those derived from multiple stands through time.