Carbon emissions from a temperate peat fire and its relevance to interannual variability of trace atmospheric greenhouse gases

Abstract

The contribution of wildfire in peatlands outside of boreal and tropical regions to interannual variability of global carbon emissions has been relatively little studied. There are 0.19 to 0.88 million km2of localized peat deposits in the temperate zone (30–50° latitude) where drainage and climate change may affect the status of this potentially large carbon pool. For example, in the coastal plain of North Carolina, USA, where wildfire is common, over 325 teragrams of carbon (Tg C) are stored in peat deposits up to 5 m deep. We estimated carbon emissions for a temperate peatland fire in North Carolina using remote sensing to reconstruct burn severity and topographic lidar to constrain peat burn depths. Total carbon emissions for the fire ranged from 1 to 3.8 Tg, with spatially heterogeneous patterns of carbon fluxes (0.2 to 11 kg C m−2) responding to variation in vegetation type, peat burn depth, soil substrate (mineral or organic), and fire severity. To maintain a carbon sink in this region at the current rates of carbon sequestration (0.109 to 0.127 kg C m−2yr−1) we estimated a fire return interval of greater than 20–80 years. Continued drainage and future drought could decrease the fire return interval to less than 20 years or increase peat burn depths thereby converting these peatlands into a net carbon source. On a global scale, this study suggests that temperate peatland fires may emit up to 0.32 petagrams of carbon during drought years, a significant contribution to interannual greenhouse gas variability.