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

Songbo Qu; Xu-Ri; Jiaoneng Yu; Fengzi Li; Da Wei; Almaz Borjigidai

doi:10.1016/j.scitotenv.2020.144277

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

Sci Total Environ. 2021 Apr 15:765:144277. doi: 10.1016/j.scitotenv.2020.144277. Epub 2020 Dec 24.

Authors

Songbo Qu¹, Xu-Ri², Jiaoneng Yu¹, Fengzi Li³, Da Wei⁴, Almaz Borjigidai⁵

Affiliations

¹ Key Laboratory of Ethnomedicine, Ministry of Education, Minzu University of China, Beijing 100081, China; Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China.
² Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: xu-ri@itpcas.ac.cn.
³ Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; The School of Ecology and Environment of Inner Mongolian University, Huhhot 010021, China.
⁴ Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China.
⁵ Key Laboratory of Ethnomedicine, Ministry of Education, Minzu University of China, Beijing 100081, China. Electronic address: almaz_b@muc.edu.cn.

PMID: 33418330
DOI: 10.1016/j.scitotenv.2020.144277

Abstract

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.

Keywords: C sequestration; CH(4)/N(2)O fluxes; CO(2) efflux; N deposition; Tibetan Plateau.