ObjectiveBy quantitative study of the effects of forest fire disturbance on soil organic carbon and its components in forest ecosystems, this paper aims to reveal the changing law of forest fire disturbance on soil organic carbon and components of forest ecosystem, with a view to providing scientific reference for the study of carbon cycle and carbon process of forest soil.

MethodTaking the subtropical fir forest of Guangdong Province as the research object, the effects of different forest fire disturbance intensity on soil organic carbon density, organic carbon component content and fine root biomass were measured quantitatively on the level of forest ecosystem by means of adjacent sample land comparison method and field investigation sampling and laboratory test analysis, to investigate the influencing mechanism of forest fire disturbance on soil organic carbon density, soil organic carbon component content and fine root biomass.

ResultForest fire disturbance had an effect on soil organic carbon density, soil organic carbon component content and fine root biomass in Chinese fir forest, and the changing trend of soil organic carbon density and soil organic carbon component content was the control > mild forest fire disturbance > moderate forest fire disturbance > severe forest fire disturbance. There was no significant difference in the effect of mild forest fire disturbance on soil organic carbon density (P > 0.05), while moderate and severe forest fire disturbance significantly reduced soil organic carbon density (P < 0.05). The biomass of soil in Chinese fir forest was lower than that in the same place, the trend of change was severe forest fire disturbance > moderate forest fire disturbance, mild forest fire disturbance only significantly reduced the fine root biomass (P < 0.05) of soil surface, while moderate and severe forest fire disturbance significantly reduced soil surface and shallow fine root biomass (P < 0.05). The soil fine root biomass of Chinese fir forest was lower than that in different forest fire interference intensity, the changing trend was severe forest fire disturbance > moderate forest fire disturbance > mild forest fire disturbance, and mild forest fire disturbance only significantly reduced the fine root biomass (P < 0.05) of soil surface. Moderate and severe forest fire disturbance significantly reduced soil surface and shallow fine root biomass (P < 0.05).

ConclusionThe results show that forest fire disturbance reduces soil organic carbon density and decreases gradually with the increase of soil profile depth. The content of soil labile organic carbon is decreasing with the increase of forest fire disturbance intensity and the decrease of soil profile after different forest fire interference intensities. By analyzing the distribution pattern and influencing mechanism of soil carbon density after forest fire disturbance, this paper provides a reference for the management of ecosystem carbon sink after forest fire disturbance and the quantitative evaluation of the influence of forest fire disturbance on the carbon bank of forest ecosystem.