University of Oulu

Wei, J., Li, X., Liu, L., Christensen, T. R., Jiang, Z., Ma, Y., Wu, X., Yao, H., and López-Blanco, E.: Radiation, soil water content, and temperature effects on carbon cycling in an alpine swamp meadow of the northeastern Qinghai–Tibetan Plateau, Biogeosciences, 19, 861–875,, 2022.

Radiation, soil water content, and temperature effects on carbon cycling in an alpine swamp meadow of the northeastern Qinghai–Tibetan Plateau

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Author: Wei, Junqi1,2; Li, Xiaoyan1,2,3,4; Liu, Lei5,6;
Organizations: 1State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
2School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
3Academy of Plateau Science and Sustainability, People’s Government of Qinghai Province and Beijing Normal University, Qinghai Normal University, Xining 810008, China
4Key Laboratory of Tibetan Plateau Land Surface Processes and Ecological Conservation, Ministry of Education, Qinghai Normal University, Xining 810016, China
5Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
6College of Resources and Environment, University of Chinese Academy of Sciences, Yuquanlu, Beijing 100049, China
7Department of Ecoscience, Arctic Research Center, Aarhus University, Roskilde 4000, Denmark
8Oulanka Research Station, University of Oulu, Oulu, Finland
9School of Geography, South China Normal University, Guangzhou 510631, China
10School of Geography and Planning, Sun Yat-sen University, Guangzhou 510275, China
11Department of Environment and Minerals, Greenland Institute of Natural Resources, Nuuk 3900, Greenland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 5.5 MB)
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Language: English
Published: Copernicus Publications, 2022
Publish Date: 2022-05-17


Predicted intensified climate warming will likely alter the ecosystem net carbon (C) uptake of the Qinghai–Tibetan Plateau (QTP). Variations in C sink–source responses to climate warming have been linked to water availability; however, the mechanisms by which net C uptake responds to soil water content in saturated swamp meadow ecosystems remain unclear. To explore how soil moisture and other environmental drivers modulate net C uptake in the QTP, field measurements were conducted using the eddy covariance technique in 2014, 2015, 2017, and 2018. The alpine swamp meadow presented in this study was a persistent and strong C sink of CO₂ (−168.0 ± 62.5 g C m⁻² yr⁻¹, average ± standard deviation) across the entire 4-year study period. A random forest machine-learning analysis suggested that the diurnal and seasonal variations of net ecosystem exchange (NEE) and gross primary productivity (GPP) were regulated by temperature and net radiation. Ecosystem respiration (Re), however, was found mainly regulated by the variability of soil water content (SWC) at different temporal aggregations, followed by temperature, the second contributing driver. We further explored how Re is controlled by nearly saturated soil moisture and temperature comparing two different periods featuring almost identical temperatures and significant differences on SWC and vice versa. Our data suggest that, despite the relatively abundant water supply, periods with a substantial decrease in SWC or increase in temperature produced higher Re and therefore weakened the C sink strength. Our results reveal that nearly saturated soil conditions during the growing seasons can help maintain lower ecosystem respiration rates and thus enhance the overall C sequestration capacity in this alpine swamp meadow. We argue that soil respiration and subsequent ecosystem C sink magnitude in alpine swamp meadows could likely be affected by future changes in soil hydrological conditions caused by permafrost degradation or accelerated thawing–freezing cycling due to climate warming.

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Series: Biogeosciences
ISSN: 1726-4170
ISSN-E: 1726-4189
ISSN-L: 1726-4170
Volume: 19
Pages: 861 - 875
DOI: 10.5194/bg-19-861-2022
Type of Publication: A1 Journal article – refereed
Field of Science: 1172 Environmental sciences
1181 Ecology, evolutionary biology
1171 Geosciences
Funding: The study was financially supported by the National Natural Science Foundation of China (NSFC 41730854 and 41971029), the Second Tibetan Plateau Scientific Expedition and Research Program (STEP 2019QZKK0306), the Strategic Priority Research Program of Chinese Academy of Sciences (XDA20100102), and projects from the State Key Laboratory of Earth Surface Processes and Resource Ecology. This study also received financial support from the China Scholarship Council (no. 201906040130) and the Faculty of Technical Sciences from Aarhus University. Additionally, Efrén López-Blanco was funded by the Greenland Research Council, grant number 80.35, financed by the Danish Program for Arctic Research.
Copyright information: © Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License.