[Simulated nitrogen deposition reduces potential nitrous oxide emissions in a natural Castanopsis carlesii forest soil].

The reactive nitrogen deposition in subtropical region of China has been increasing annually, which affects biogeochemical processes in forest soils. In this study, three treatments were established, including control (no N addition, CK), low nitrogen deposition (40 kg·hm ^-2 ·a ^-1 , LN), and high nitrogen deposition (80 kg·hm ^-2 ·a ^-1 , HN) to study the response of denitrifying functional genes and potential N ₂ O emissions to simulated nitrogen deposition in the soils of a natural Castanopsis carlesii forest. Results showed that HN significantly decreased soil potential N ₂ O emission, while 8-year nitrogen deposition did not affect the abundances of nirS , nirK , nosZ Ⅰ and nosZ Ⅱ. However, the abundance of nosZ Ⅰwas significantly higher than nosZ Ⅱ in all the treatments, indicating that nosZ Ⅰ dominated over nosZ Ⅱ in the acidic soils. HN significantly decreased the ratio of ( nirK+nirS )/( nosZ Ⅰ +nosZ Ⅱ), which was positively correlated with soil pH. The results suggested that long-term high nitrogen deposition reduced soil pH and the abundance ratio of ( nirK+nirS )/( nosZ Ⅰ +nosZ Ⅱ), which subsequently reduced the potential N ₂ O emission.