Contrasting responses after fires of the source components of soil respiration and ecosystem respiration

Wildfire is an important ecological disturbance that can have cascading effects on ecosystem carbon (C) fluxes. Ecosystem respiration (ER) and soil respiration (SR) account for two of the largest terrestrial C fluxes to the atmosphere, and they play critical roles in regulating C–climate feedbacks. Here, the responses of ER, SR and their source components to experimental burning in a meadow grassland on the Tibetan Plateau were investigated. Fire treatment increased ER by 9% but decreased SR by 15%. The contrasting post‐fire responses of SR and ER can be explained by the behaviour of their source components; that is, fire increased aboveground plant respiration (Rₐgb) by 37%, but decreased heterotrophic respiration (HR) by 21%. Increases in ER and Rₐgb were mainly related to enhanced plant productivity, whereas smaller SR and HR were associated with reductions in microbial biomass and soil moisture. Accounting for the responses of ER, SR and their intrinsic components has advanced our understanding of how fire affects ecosystem C fluxes. HIGHLIGHTS: Fire treatment increased ecosystem respiration (ER) and aboveground plant respiration. Fire treatment decreased soil respiration (SR) and heterotrophic respiration (HR). Increases in ER and aboveground plant respiration were related to plant productivity. Reductions in SR and HR were caused by the suppressed microbial activity.