Carbon storage in southern boreal forests following fire

Abstract

>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.