Effects of fire on the soil microbial metabolic quotient: A global meta-analysis

Soil microorganisms play an essential role in the biogeochemical cycles; however, the response of soil microorganisms to fire is largely unknown. Understanding this response has become increasingly important in the current context of global ecosystem disturbance, which is characterized by an increased frequency of fires. Therefore, a global meta-analysis of 371 cases from 81 published studies was conducted to explore the comprehensive effects of fires on soil microbial properties. The results show that fires significantly increased microbial metabolic quotient (qCO2), by 19.45% on average, and decreased soil microbial biomass carbon (MBC) by 8.41% and fungal biomass by 27.17%. Moreover, the response of these microbial indices to fires intensified with increasing fire intensity. In addition, ecosystem types and climate zones have an impact on the response of MBC and qCO2 to fires. Among them, MBC and qCO2 in coniferous forests and continental climate zones are the most sensitive to fires. A correlation analysis displayed that the response of soil organic carbon (SOC) to fires was significantly and positively correlated with the response of MBC but negatively correlated with the response of qCO2. Furthermore, fires reduced SOC in the short term, but had no significant impact in the long term. Collectively, this study emphasizes the need to pay greater attention to forest fire protection in arid areas under global climate change.