A meta-analysis on the response of microbial biomass, dissolved organic matter, respiration, and N mineralization in mineral soil to fire in forest ecosystems

The effects of fire on labile soil C and N in forest ecosystems are important for understanding C sequestration and N cycling not only because labile soil C and N are often variables that determine soil fertility but also because the role of soils as a source or sink for C is important on an ecosystem and on the regional level. In the current study, the literature on the effects of fire on soil organic C, total N, microbial biomass C and N, dissolved organic C, and total N, respiration, and N mineralization in mineral soil was reviewed, and the results of a meta-analysis on literature data were reported. Overall, fire significantly increased the soil total N, microbial biomass N, dissolved organic C, and total N, but decreased soil organic C, microbial biomass C, respiration and N mineralization. Among the significant effects of different fire types, wildfire had the higher effects on the soil organic C, total N, microbial biomass C and N, dissolved total N and respiration of soil than prescribed fire. In addition, responses of soil organic C, total N and N mineralization to wildfire depended on forest type and natural zone. Positive responses of soil organic C, total N were found in broadleaved forests and Mediterranean zones, and negative responses in coniferous forests and temperate zones. Wildfire significantly decreased N mineralization in coniferous forests. The effects of fire on soil microbial biomass C and N, dissolved organic C and N mineralization generally decreased with time after the fire. In general, the effects of fire on soil organic C, microbial biomass C, and dissolved total N and N mineralization decreased with increasing soil depth. These results suggest that fire increases C and N availability and increases microbial activity, which consequently decreases the potential rates of C sequestration.