Effects of fire on soil respiration and its components in a Dahurian larch (Larix gmelinii) forest in northeast China: Implications for forest ecosystem carbon cycling

Abstract Fire plays a critical part in regulating soil carbon (C) budgets in forest ecosystems. However, few studies have focused on the effects of fire on soil respiration (Rs) and its heterotrophic (Rh) and autotrophic (Ra) components. In this study, we examined the response of Rs, Rh, and Ra to fire and the driving factors that affect Rs after a fire disturbance in a Dahurian larch (Larix gmelinii) forest in northeastern China. Fire disturbance significantly increased Rh by approximately 24% and significantly reduced Ra by approximately 66% in burned plots compared to unburned plots. The ratio of Rh to Rs significantly increased from 0.57 in the unburned plots to 0.79 in the burned plots. Fire disturbance also led to cumulative Rs C efflux increasing by approximately 10% and 28% during the growing season and the period of spring freeze–thaw cycles (FTC) in the burned plots. Furthermore, using structural equation modelling, we showed that T5 (soil temperature at 5 cm depth) was the main abiotic factor affecting Rs in both unburned and burned plots. Fine root biomass (FR) was the dominant biotic driver of Rs in the control plots, whereas microbial biomass carbon (MBC) was the dominant biotic driver of Rs in burned plots. Our findings demonstrated a significant discrepancy in the response of Rs components to fire disturbance. Forest fires can cause considerable losses of soil C in a cold temperate forest ecosystem, which suggests that proactive management of forest regeneration should be carried out after forest fire disturbances.