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Atmospheric water vapor and soil moisture jointly determine the spatiotemporal variations of CO2 fluxes and evapotranspiration across the Qinghai-Tibetan Plateau grasslands
Li, Hongqin1,2; Wang, Chunyu2,6; Zhang, Fawei2,3,5; He, Yongtao4; Shi, Peili4; Guo, Xiaowei2; Wang, Junbang4; Zhang, Leiming4; Li, Yingnian2,5; Cao, Guangmin2; Zhou, Huakun2,3
2021-10-15
Source PublicationSCIENCE OF THE TOTAL ENVIRONMENT
ISSN0048-9697
Volume791Pages:13
Corresponding AuthorZhang, Fawei(mywing@126.com) ; Li, Yingnian(ynli@nwipb.cas.cn)
AbstractAlpine grasslands play important functions in mitigating climate change and regulating water resources. However, the spatiotemporal variability of their carbon and water budgets remains unquantified. Here, 47 site-year observations of CO2 and water vapor fluxes (ET) are analyzed at sites situated along a hydrothermal gradient across the Qinghai-Tibetan Plateau, including an alpine wetland (wettest), an alpine shrub (coldest), an alpine meadow, an alpine meadow-steppe, and an alpine steppe (driest and warmest). The results show that the benchmarks for annual net ecosystem exchange (NEE) are -79.3, -77.8, -66.7, 20.2, and 100.9 g C m(-2) year(-1) at the meadow, shrub, meadow-steppe, steppe, and wetland, respectively. The peak daily NEE normalized by peak leaf area index converges to 0.93 g C m(-2) d(-1) at the 5 sites. Except in the wetland (722.8 mm), the benchmarks of annual ET fluctuate from 511.0 mm in the steppe to 589.2 mm in the meadow. Boosted regression trees-based analysis suggests that the enhanced vegetation index (EVI) and net radiation (Rn) determine the variations of growing season monthly CO2 fluxes and ET, respectively, although the effect is to some extent site-specific. Inter-annual variability in NEE, ecosystem respiration (RES), and ET are tightly (R-2 > 0.60) related to the inter growing season NEE, RES, and ET, respectively. Both annual RES and annual NEE are significantly constrained by annual gross primary productivity (GPP), with 85% of the per-unit GPP contributing to RES (R-2 = 0.84) and 15% to NEE (R-2 = 0.12). Annual GPP significantly correlates with annual ET alone at the drier sites of the meadow-steppe and the steppe, suggesting the coupling of carbon and water is moisture-dependent in alpine grasslands. Over half of the inter-annual spatial variability in GPP, RES, NEE, and ET is explained by EVI, atmospheric water vapor, topsoil water content, and bulk surface resistance (rs), respectively. Because the spatial variations of EVI and rs are strongly regulated by atmospheric water vapor (R-2 = 0.48) and topsoil water content (R-2 = 0.54), respectively, we conclude that atmospheric water vapor and topsoil water content, rather than the expected air/soil temperatures, drive the spatiotemporal variations in CO2 fluxes and ET across temperature-limited grasslands. These findings are critical for improving predictions of the carbon sequestration and water holding capacity of alpine grasslands. (C) 2021 Published by Elsevier B.V.
KeywordCO2 and water vapor exchanges Boosted regression trees Enhanced vegetation index Net radiation Bulk surface resistance Alpine grasslands
DOI10.1016/j.scitotenv.2021.148379
WOS KeywordALPINE MEADOW ECOSYSTEM ; CARBON-DIOXIDE EXCHANGE ; TERRESTRIAL ECOSYSTEMS ; USE EFFICIENCY ; ENERGY ; TEMPERATURE ; SHRUBLAND ; VARIABILITY ; CHINA
Indexed BySCI
Language英语
Funding ProjectNational Key RD Program[2017YFA0604802] ; National Key RD Program[2017YFA0604801] ; Chinese Academy of SciencesPeople's Government of Qinghai Province Joint Grant on Sanjiangyuan National Park Research[YHZX202007] ; National Natural Science Foundation of China[41730752] ; National Natural Science Foundation of China[41877547] ; Qinghai Innovation Platform Construction Project[2021ZJY01]
Funding OrganizationNational Key RD Program ; Chinese Academy of SciencesPeople's Government of Qinghai Province Joint Grant on Sanjiangyuan National Park Research ; National Natural Science Foundation of China ; Qinghai Innovation Platform Construction Project
WOS Research AreaEnvironmental Sciences & Ecology
WOS SubjectEnvironmental Sciences
WOS IDWOS:000686018500016
PublisherELSEVIER
Citation statistics
Cited Times:2[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://ir.igsnrr.ac.cn/handle/311030/164670
Collection中国科学院地理科学与资源研究所
Corresponding AuthorZhang, Fawei; Li, Yingnian
Affiliation1.Luoyang Normal Univ, Coll Life Sci, Luoyang 471934, Henan, Peoples R China
2.Chinese Acad Sci, Northwest Inst Plateau Biol, Key Lab Adaptat & Evolut Plateau Biota, Xining 810001, Qinghai, Peoples R China
3.Chinese Acad Sci, Northwest Inst Plateau Biol, Qinghai Prov Key Lab Restorat Ecol Cold Reg, Xining 810001, Qinghai, Peoples R China
4.Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Key Lab Ecosyst Network Observat & Modeling, Synth Res Ctr Chinese Ecosyst Res Network, Beijing 100101, Peoples R China
5.Chinese Acad Sci, Inst Sanjiangyuan Natl Pk, Xining 810001, Qinghai, Peoples R China
6.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
Recommended Citation
GB/T 7714
Li, Hongqin,Wang, Chunyu,Zhang, Fawei,et al. Atmospheric water vapor and soil moisture jointly determine the spatiotemporal variations of CO2 fluxes and evapotranspiration across the Qinghai-Tibetan Plateau grasslands[J]. SCIENCE OF THE TOTAL ENVIRONMENT,2021,791:13.
APA Li, Hongqin.,Wang, Chunyu.,Zhang, Fawei.,He, Yongtao.,Shi, Peili.,...&Zhou, Huakun.(2021).Atmospheric water vapor and soil moisture jointly determine the spatiotemporal variations of CO2 fluxes and evapotranspiration across the Qinghai-Tibetan Plateau grasslands.SCIENCE OF THE TOTAL ENVIRONMENT,791,13.
MLA Li, Hongqin,et al."Atmospheric water vapor and soil moisture jointly determine the spatiotemporal variations of CO2 fluxes and evapotranspiration across the Qinghai-Tibetan Plateau grasslands".SCIENCE OF THE TOTAL ENVIRONMENT 791(2021):13.
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