Clear-cut and forest regeneration increase soil N₂O emission in Cunninghamia lanceolata plantations

Forest regeneration after clear-cut has been practiced extensively to establish a new stand. However, the effects of forest regeneration on soil N2O emission and the related changes in soil environment factors have been rarely examined in managed plantation forests. A 21-month field trial was conducted to investigate the effects of two different regeneration practices following clear-cut on soil N2O emission and related environmental factors in a Cunninghamia lanceolata plantation. The trial included three treatments, clear-cut and natural regeneration (CN), clear-cut and artificial overall regeneration (CAO), and uncut control (UC). Compared with the control, CN, and CAO increased cumulative soil N2O emissions (P < 0.05) by 76%, and 170%, respectively. Soil N2O fluxes were positively (P < 0.05) correlated with soil temperature, moisture, microbial biomass C and N, NO3−-N, water-soluble organic C and N, and NH4+-N concentrations. We conclude that clear-cut and associated natural regeneration (CN) increased N2O fluxes due to the increased soil temperature, and the increased concentrations of NO3−-N, microbial biomass C and N, and water-soluble organic C and N; and artificial overall regeneration increased soil N2O fluxes due to the increased concentrations of soil NO3−-N, microbial biomass C and N. The results highlighted that artificial overall regeneration with higher soil disturbance intensity in clear-cut stands would exacerbate soil N2O emission.