Nitrogen deposition accelerates greenhouse gas emissions at an alpine steppe site on the Tibetan Plateau

• Published in: The Science of the total environment 2021-04, Vol.765, p.144277-144277, Article 144277
• Main Authors: Qu, Songbo, Xu-Ri, Yu, Jiaoneng, Li, Fengzi, Wei, Da, Borjigidai, Almaz
• Format: Article
• Language: English
• Subjects: C sequestration; CH4/N2O fluxes; CO2 efflux; N deposition; Tibetan Plateau
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.144277

The increase in atmospheric N deposition can alter the exchange of greenhouse gas (GHG) between the biosphere and atmosphere. The effect of N deposition on GHG is poorly understood in alpine steppe. Therefore, we conducted a 4-year experiment with multilevel N addition of 0, 10, 20, 40, 80, 160 kg N ha−1 using the static chamber and gas chromatography method to quantify responses of GHG fluxes and characterize the relationship between GHG fluxes and N addition rate in Namco located in the alpine steppe in the central Tibetan Plateau (TP). The mean CO2 efflux, CH4 uptake, N2O emission during growing seasons across four years were 33.59 ± 16.41 mg C m−2 h−1, −56.42 ± 29.20 μg C m−2 h−1, 0.67 ± 4.40 μg N m−2 h−1 respectively. CO2 efflux increased 1.55–22.6%, CH4 uptake decreased 5.96–20.1%, N2O emission increased 37.3–133.5% with N addition. We also observed a critical threshold of 40 kg N ha−1 a−1 of N addition above which the increase rate of N2O emission would diminish. Our current results implied that under the background of future N deposition, N induced C sequestration might be offset by GHG balance causing a heating effect to the climate. [Display omitted] •CO2 and N2O fluxes will increase and CH4 uptake will decrease under N addition.•A critical threshold of 40 kg N ha−1 a−1 of N addition was observed for N2O fluxes.•Tibetan Plateau alpine steppe might act as C source with future N deposition continue.