Observational field study reveals decadal soil organic carbon decline before recovery in burned forest ecosystems, indicating prolonged vulnerability following severe wildfire.
Key Points
Investigate the temporal dynamics and recovery patterns of soil organic carbon and its fractions across a multi-decade post-fire chronosequence in a dry-warm valley region.
Utilized a space-for-time substitution approach across severely burned and unburned forest sites covering a 26-year timeline (1996 to 2021) in the Anning River Basin, China.
Quantified total soil organic carbon (SOC) and four fractions—readily oxidizable carbon (ROC), non-labile organic carbon (NLOC), particulate organic carbon (POC), and mineral-associated organic carbon (MOC)—across varying soil depths and slope aspects.
Analyzed correlations between carbon fractions and soil physicochemical properties, including pH, bulk density, porosity, clay content, fine root biomass, total nitrogen, total phosphorus, and cation exchange capacity.
SOC and its components were significantly negatively correlated with soil depth and slope aspect (p < 0.05), but significantly positively correlated with time since fire (p < 0.01).
SOC, ROC, NLOC, POC, and MOC showed an initial decline starting approximately 5 years post-fire and persisting through the first 10 years of recovery before increasing, with POC requiring over 20 years to begin increasing.
Bulk density and pH were significantly negatively correlated with SOC components (p < 0.01), whereas soil porosity, clay, fine root biomass, total nitrogen, total phosphorus, and cation exchange capacity were significantly positively correlated (p < 0.05).