QUANTIFYING THE SPATIAL DISTRIBUTION OF PYROGENIC CARBON FOLLOWING THE 2018 BUZZARD FIRE IN THE GILA NATIONAL FOREST, NEW MEXICO

Pyrogenic carbon (PyC), which is produced during wildfires from the incomplete combustion of biomass, has a longer mean soil residence time than non-pyrogenically altered organic matter making it a major component of global soil carbon stocks. Recent observations indicate that current estimates of PyC residence times may be inaccurate due to poorly constrained estimates of post-fire lateral transport of PyC via physical (i.e., erosive) processes. The post-fire redistribution of PyC has the potential to influence the regional carbon stock as well as the turnover time of PyC within the soil. Quantifying the post-fire lateral transport and redistribution of PyC is therefore critical to understanding the impact of wildfire on carbon cycling in upland watersheds. The goal of this study is to quantify spatial variations in near-surface (0–5 cm) PyC one year after a wildfire in the Gila National Forest, New Mexico. We aim to relate the spatial distribution of PyC to hydrogeomorphic factors known to control rates of sediment transport, including burn severity, slope, and contributing area, with the goal of explaining the movement of PyC throughout our burned study area. Hydrologic monitoring of the burned area during the first post-fire year suggests differences in runoff magnitude as a function of burn severity, with debris flows, rilling, and gullying being commonly observed in areas burned at moderate to high severity. Although greater amounts of PyC may have been produced in areas burned at moderate or high severity, we hypothesize that there will be more PyC remaining near the soil surface in areas burned at low severity relative to areas burned at moderate or high severity. Here, we present preliminary results and propose a methodology for capturing relevant field data as well as the measurement of PyC concentration.