Effects of Wildfire on Soil CO2 Emission and Bacterial Community in Plantations

In order to study the effects of wildfires on soil carbon dioxide (CO₂) emissions and microbial communities in planted forests, <i>Pinus massoniana</i> Lamb. and <i>Cunninghamia lanceolata</i> (Lamb.) Hook. forests were selected as the research subjects. Through a culture test with 60 days of indoor constant temperature, the soil physical and chemical properties, organic carbon mineralization, organic carbon components, enzyme activity, and microbial community structure changes of the two plantations after fire were analyzed. The results showed that wildfires significantly reduced soil CO₂ emissions from the <i>Pinus massoniana</i> forests and <i>Cunninghamia lanceolata</i> forests by 270.67 mg·kg^-1 and 470.40 mg·kg^-1, respectively, with <i>Cunninghamia lanceolata</i> forests exhibiting the greatest reduction in soil CO₂ emissions compared to unburned soils. Bioinformatics analysis revealed that the abundance of soil <i>Proteobacteria</i> in the <i>Pinus massoniana</i> and <i>Cunninghamia lanceolata</i> forests decreased by 6.00% and 4.55%, respectively, after wildfires. Additionally, redundancy analysis indicated a significant positive correlation between <i>Proteobacteria</i> and soil CO₂ emissions, suggesting that the decrease in <i>Proteobacteria</i> may inhibit soil CO₂ emissions. The <i>Cunninghamia lanceolata</i> forests exhibited a significant increase in soil available nutrients and inhibition of enzyme activities after the wildfire. Additionally, soil CO₂ emissions decreased more, indicating a stronger adaptive capacity to environmental changes following the wildfire. In summary, wildfire in the <i>Cunninghamia lanceolata</i> forests led to the most pronounced reduction in soil CO₂ emissions, thereby mitigating soil carbon emissions in the region.