Abstract: Combined with the antibiotic inhibition technique, we examined the responses of soil fungal and bacterial N₂O emissions in a laboratory culture experiment. Soil samples were collected from fixed plots with long-term (eight years) nitrogen application and precipitation reduction in a broad-leaved Korean pine forest in Changbai Mountains. Results showed that soil N₂O emissions were 0.79 nmol·g^-1·h^-1 in the control. Nitrogen application, precipitation reduction, and simultaneous precipitation reduction and nitrogen application significantly enhanced soil N₂O emissions, which were 3.55, 1.84 and 1.84 nmol·g^-1·h^-1, respectively. There was a significant interaction between precipitation reduction and nitrogen application. Bacterial N₂O emissions were affected by nitrogen application and precipitation reduction. Nitrogen application promoted bacterial N₂O emissions, thereby promoting total soil N₂O emissions. Fungal N₂O emissions were mainly affected by precipitation reduction. Simultaneous precipitation reduction and nitrogen application promoted fungal N₂O emissions, thereby promoting total soil N₂O emissions. The increase in N₂O emissions caused by precipitation reduction treatment was attributed to the interaction of bacteria and fungi. In the control, precipitation reduction, and nitrogen application treatments, N₂O emissions were mainly contributed by bacteria, with relative contribution rates of 90.3%, 68.2% and 91.1%, respectively. In the nitrogen application and precipitation reduction treatment, N₂O emissions were mainly contributed by fungi, with a contribution rate of 68.5%. Therefore, long-term nitrogen application under drought scenario would alter the main microbial species involved in soil N₂O emission, directly affect the amount of N₂O emissions from soil fungi and bacteria, thereby affecting total soil N₂O emissions, which influence nitrogen cycling in forest ecosystems.

Key words: soil N₂O emission, fungi, bacteria, nitrogen deposition, precipitation reduction