Controls on carbon consumption during Alaskan wildland fires

Abstract

AbstractA method was developed to estimate carbon consumed during wildland fires in interior Alaska based on medium‐spatial scale data (60 m cell size) generated on a daily basis. Carbon consumption estimates were developed for 41 fire events in the large fire year of 2004 and 34 fire events from the small fire years of 2006–2008. Total carbon consumed during the large fire year (2.72 × 106 ha burned) was 64.7 Tg C, and the average carbon consumption during the small fire years (0.09 × 106 ha burned) was 1.3 Tg C. Uncertainties for the annual carbon emissions ranged from 13% to 21%. Carbon consumed from burning of black spruce forests represented 76% of the total during large fire years and 57% during small fire years. This was the result of the widespread distribution of black spruce forests across the landscape and the deep burning of the surface organic layers common to these ecosystems. Average carbon consumed was 3.01 kg m−2 during the large fire year and 1.69 kg m−2 during the small fire years. Most of the carbon consumption was from burning of ground layer fuels (85% in the large fire year and 78% in small fire years). Most of the difference in average carbon consumption between large and small fire years was in the consumption of ground layer fuels (2.60 vs. 1.31 kg m−2 during large and small fire years, respectively). There was great variation in average fuel consumption between individual fire events (0.56–5.06 kg m−2) controlled by variations in fuel types and topography, timing of the fires during the fire season, and variations in fuel moisture at the time of burning.