Soil water availability dominates the sustainability of carbon flux under heatwave in Qinghai-Xizang Plateau alpine grasslands

doi:10.1093/jpe/rtag106

J Plant Ecol ›› Advance articles DOI:10.1093/jpe/rtag106

Soil water availability dominates the sustainability of carbon flux under heatwave in Qinghai-Xizang Plateau alpine grasslands

Kuangyu Li^1,2,3, Zhi Chen^1,2,3*, Jianqing Du^2,3,4*, Meng Yang¹, Tianxiang Hao¹, Yong Lin^1,2, Wencong Lv⁵, Yanfen Wang^2,3, Guirui Yu^1,3

1 Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;
2 Beijing Yanshan Earth Critical Zone National Research Station, University of Chinese Academy of Sciences, Beijing 101408, China;
3 College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China;
4 State Key Laboratory of Earth System Numerical Modeling and Application, Chinese Academy of Sciences, Beijing 101408, China;
5 Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
^*Correspondence author: Z. Chen (chenz@igsnrr.ac.cn) and J.Q. Du (jqdu@ucas.ac.cn)

Received:2025-08-15 Revised:2026-04-06 Accepted:2026-04-22 Published:2026-05-21
Supported by:
This work was supported by the Project for Young Scientists in Basic Research of Chinese Academy of Sciences (YSBR-037), National Natural Science Foundation of China (42407285), National Key Research and Development Program of China (2025YFF0812101), and National Natural Science Foundation of China (42261144688, 32588202).

土壤水分有效性主导青藏高原高寒草地热浪期间碳通量的稳定性

Abstract

Abstract: Over recent decades, the increasing frequency of extreme heat events has led to warmer and drier conditions that significantly impact vegetation productivity and ecosystem carbon sequestration. Based on tower-based flux data (2022-2023) from two contrasting alpine ecosystems (alpine meadow and alpine wetland) on the Qinghai-Xizang Plateau (QXP), we assessed the impact of the 2022 heatwave on carbon fluxes and their underlying mechanisms. The results demonstrated that the heatwave strongly suppressed carbon uptake in the alpine meadow, reducing net ecosystem productivity (NEP), gross primary productivity (GPP), and carbon use efficiency (CUE) by 36.9%, 17.0%, and 14.4%, respectively, while ecosystem respiration (ER) remained unchanged. In contrast, carbon fluxes and CUE in the alpine wetland were largely insensitive to the heatwave, indicating substantially higher thermal resistance. The alpine meadow exhibited post-heatwave legacy effects, with persistent declines in GPP, ER, and NEP, and incomplete recovery of carbon uptake by the end of the growing season. Moreover, the heatwave strengthened soil water content (SWC) as the dominant control on carbon fluxes across both ecosystems. Mechanistically, soil moisture depletion during the heatwave directly constrained GPP and NEP, while elevated VPD further intensified carbon losses through reduced canopy conductance. By contrast, stable soil water availability in the alpine wetland prevented water limitation, enabling higher temperatures to stimulate vegetation growth and carbon uptake. These results highlight the high sensitivity of the QXP alpine carbon sink to climate extremes and the risk of disproportionate productivity losses in water-limited alpine regions under future climate intensification.

Key words: Alpine Meadow, Alpine Wetland, Heatwave, Stability, Legacy impacts, Eddy covariance

摘要：
近几十年来，极端高温事件频发，区域暖干化趋势日益显著，严重影响植被生产力与生态系统固碳能力。本研究基于青藏高原高寒草甸与高寒湿地两类典型高寒生态系统2022-2023年通量塔观测数据，系统分析了2022年热浪事件对生态系统碳通量的影响及其调控机制。结果表明：热浪显著抑制了高寒草甸的碳吸收能力，其生态系统净生产力(NEP)、总初级生产力(GPP)与碳利用效率(CUE)分别显著降低36.9%、17.0%和14.4%，生态系统呼吸(ER)则无明显变化；高寒湿地碳通量与碳利用效率在热浪期间未发生显著变化，表现出更强的抵抗力。高寒草甸存在明显的遗留效应，热浪结束后GPP、ER与NEP仍持续降低，直到生长季结束固碳能力仍未恢复至正常水平。热浪进一步增强了土壤含水量对两类生态系统碳通量的主导调控作用。机理层面，热浪引发的土壤水分亏缺直接抑制了GPP与NEP，饱和水汽压差(VPD)升高则通过降低冠层导度进一步加剧碳排放；而高寒湿地土壤水分状况维持稳定，未受到水分胁迫限制，升温反而促进植被生长与碳吸收。本研究揭示了青藏高原高寒碳汇对极端气候事件高度敏感，未来气候变暖和极端事件频发背景下，水分受限的高寒生态系统或将面临植被生产力衰退、碳汇功能失衡的潜在风险。

关键词: 高寒草甸, 高寒湿地, 热浪, 稳定性, 遗留效应, 涡度协方差

Kuangyu Li, Zhi Chen, Jianqing Du, Meng Yang, Tianxiang Hao, Yong Lin, Wencong Lv, Yanfen Wang, Guirui Yu. Soil water availability dominates the sustainability of carbon flux under heatwave in Qinghai-Xizang Plateau alpine grasslands[J]. J Plant Ecol, DOI: 10.1093/jpe/rtag106.

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