Preprints
https://doi.org/10.5194/bg-2022-53
https://doi.org/10.5194/bg-2022-53
 
20 May 2022
20 May 2022
Status: this preprint is currently under review for the journal BG.

Effects of water table level and nitrogen deposition on methane and nitrous oxide emissions in an alpine peatland

Wantong Zhang1,2,4, Zhengyi Hu2, Joachim Audet4, Thomas Alexander Davidson4, Enze Kang1,3, Xiaoming Kang1,3, Yong Li1,3, Xiaodong Zhang1,3, and Jinzhi Wang1,3 Wantong Zhang et al.
  • 1Institute of Wetland Research, Chinese Academy of Forestry, Beijing Key Laboratory of Wetland Services and Restoration, Beijing 100091, China
  • 2Sino-Danish Centre for Education and Research, University of Chinese Academy of Sciences, Beijing 100049, China
  • 3Sichuan Zoige Wetland Ecosystem Research Station, Tibetan Autonomous Prefecture of Aba 624500, China
  • 4Department of Ecoscience and Arctic Research Centre (ARC), Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark

Abstract. Alpine peatlands are recognized as a major natural contributor to the budgets of atmospheric methane (CH4) but as a weak nitrous oxide (N2O) source. Anthropogenic activities and climate change have put these fragile nitrogen (N)-limited peatlands under pressure by altering water table (WT) levels and enhancing N deposition. The response of greenhouse gas (GHG) emissions from these peatlands to these twin changes is uncertain. To address this knowledge gap, we conducted a mesocosm experiment in 2018 and 2019 investigating individual and interactive effects of three WT levels (WT-30, 30 cm below soil surface; WT0, soil-water interface; WT10, 10 cm above soil surface) and multiple levels of N deposition (0, 20, 40, 80 and 160 kg N ha-1 yr-1) on growing season CH4 and N2O emissions in the Zoige alpine peatland, Qinghai-Tibetan Plateau. We found that the elevated WT levels increased CH4 emission, while the N deposition had non-linear effects (stimulation at moderate levels and inhibition at higher). In contrast no clear pattern of the effect of WT levels on the cumulative N2O emission was evident, while N deposition led to a consistent and linear increase (emission factor: 2.3 %–2.8 % and 1 % in IPCC), and this was dependent on the WT levels. Across the two years, the scenario with the greatest GWP (from CH4 and N2O) was an N deposition of ca. 20 kg N ha-1 yr-1 and high WT levels (at soil surface or above). Given the current N deposition in the Zoige alpine peatland (1.08–17.81 kg N·ha-1), our results suggested that the CH4 and N2O emissions from the alpine peatlands could greatly increase in response to the possible doubling N deposition in the future. We believe that our results provide insights into how interactions between climate change and human disturbance will alter GHG emissions from this globally important habitat.

Wantong Zhang et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2022-53', Anonymous Referee #1, 10 Jun 2022
    • AC1: 'Reply on RC1', Jinzhi Wang, 21 Jul 2022
  • RC2: 'Comment on bg-2022-53', Anonymous Referee #2, 18 Jun 2022
    • AC2: 'Reply on RC2', Jinzhi Wang, 21 Jul 2022

Wantong Zhang et al.

Wantong Zhang et al.

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Short summary
This work focused on the greenhouse gas emissions from alpine peatlands in response to the interactive effects of altered water table levels and nitrogen deposition. Across the two-year mesocosm experiment, N deposition showed non-linear effects on CH4 emissions and linear effects on N2O emissions, dependent on the water table levels. Our results implied that the projected doubling N deposition by 2050 could potentially increase emissions of methane and nitrous oxide in alpine peatlands.
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