Alpine ecosystems may be contribute to increasing atmospheric carbon dioxide (CO2) concentrations under intensified climate change on the Tibetan Plateau (TP). The eddy covariance technique was used in this research to examine how net ecosystem CO2 exchange (NEE) and its component fluxes, gross primary production (GPP), and ecosystem respiration (ER) varied over 10 years (from 2010 to 2019) in an alpine meadow on the eastern TP. This alpine meadow acted as a sink of CO2, with a mean of –92.5 ± 54.9 g C m–2 year–1 during the measurement period. The exponential ER response model is unsuitable for water stress conditions, potentially resulting in an overestimation of ER and GPP. The intra-annual variations of daily GPP and ER were more related to photosynthetic active radiation (PAR), soil temperature (Ts) and normalized difference vegetation index (NDVI), but the daily NEE during growing seasons shifts between PAR-dependent and NDVI-dependent with changes in soil water content (SWC). At monthly and seasonal scales, the sensitivity of GPP to NDVI and water conditions was higher than that of ER. The inter-annual variability in NEE was significantly related to the SWC. These findings are critical for understanding the response mechanism of carbon dynamics to the changing biotic and abiotic conditions in the TP.

中文翻译：

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水资源供应控制青藏高原东部高寒草甸二氧化碳通量的季节和年际变化


在青藏高原（TP）气候变化加剧的情况下，高山生态系统可能导致大气二氧化碳（CO2）浓度增加。本研究使用涡度协方差技术来研究高山地区 10 年来（2010 年至 2019 年）净生态系统二氧化碳交换 (NEE) 及其组成通量、总初级生产力 (GPP) 和生态系统呼吸 (ER) 的变化情况高原东部草甸。该高山草甸充当二氧化碳汇，测量期间的平均值为 –92.5 ± 54.9 g C m–2year–1。指数 ER 响应模型不适合水分胁迫条件，可能导致 ER 和 GPP 的高估。日GPP和ER的年内变化与光合有效辐射（PAR）、土壤温度（Ts）和归一化植被指数（NDVI）相关，但生长季日NEE在PAR依赖和NDVI依赖之间变化。取决于土壤含水量（SWC）的变化。在月度和季节尺度上，GPP对NDVI和水分条件的敏感性高于ER。 NEE的年际变化与SWC显着相关。这些发现对于理解碳动力学对青藏高原生物和非生物条件变化的响应机制至关重要。