气候变化领域集成服务门户(CCPortal): Atmospheric water vapor and soil moisture jointly determine the spatiotemporal variations of CO2 fluxes and evapotranspiration across the Qinghai-Tibetan Plateau grasslands

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DOI	10.1016/j.scitotenv.2021.148379
	Atmospheric water vapor and soil moisture jointly determine the spatiotemporal variations of CO2 fluxes and evapotranspiration across the Qinghai-Tibetan Plateau grasslands
	Li, Hongqin; Wang, Chunyu; Zhang, Fawei; He, Yongtao; Shi, Peili; Guo, Xiaowei; Wang, Junbang; Zhang, Leiming; Li, Yingnian; Cao, Guangmin; Zhou, Huakun
通讯作者	Zhang, FW ; Li, YN (通讯作者)，23 Xinning St, Xining 810001, Qinghai, Peoples R China.
发表日期	2021
ISSN	0048-9697
EISSN	1879-1026
卷号	791
英文摘要	Alpine 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.
关键词	ALPINE MEADOW ECOSYSTEM CARBON-DIOXIDE EXCHANGE TERRESTRIAL ECOSYSTEMS USE EFFICIENCY ENERGY TEMPERATURE SHRUBLAND VARIABILITY CHINA
英文关键词	CO2 and water vapor exchanges; Boosted regression trees; Enhanced vegetation index; Net radiation; Bulk surface resistance; Alpine grasslands
语种	英语
WOS研究方向	Environmental Sciences & Ecology
WOS类目	Environmental Sciences
WOS记录号	WOS:000686018500016
来源期刊	SCIENCE OF THE TOTAL ENVIRONMENT
来源机构	中国科学院西北生态环境资源研究院
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/254124
作者单位	[Li, Hongqin] Luoyang Normal Univ, Coll Life Sci, Luoyang 471934, Henan, Peoples R China; [Li, Hongqin; Wang, Chunyu; Zhang, Fawei; Guo, Xiaowei; Li, Yingnian; Cao, Guangmin; Zhou, Huakun] Chinese Acad Sci, Northwest Inst Plateau Biol, Key Lab Adaptat & Evolut Plateau Biota, Xining 810001, Qinghai, Peoples R China; [Zhang, Fawei; Zhou, Huakun] Chinese Acad Sci, Northwest Inst Plateau Biol, Qinghai Prov Key Lab Restorat Ecol Cold Reg, Xining 810001, Qinghai, Peoples R China; [He, Yongtao; Shi, Peili; Wang, Junbang; Zhang, Leiming] 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; [Zhang, Fawei; Li, Yingnian] Chinese Acad Sci, Inst Sanjiangyuan Natl Pk, Xining 810001, Qinghai, Peoples R China; [Wang, Chunyu] Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式 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]. 中国科学院西北生态环境资源研究院,2021,791.
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.
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).