| 摘 要： |
The changes in the carbon sink function of sensitive and fragile alpine ecosystems under climate change are widely concerned. Radiation, temperature, and water resources play important roles in regulating carbon assimilation. Therefore, it is important to detect the optimal configuration of environmental factors for the photosynthesis of alpine meadow ecosystems. In this study, based on 10-year flux and corresponding environ-mental observations in a typical alpine meadow ecosystem, the optimal environmental configuration that could realistically occur in the natural world for photosynthesis was detected. The results indicated that the temper-ature and water conditions were the primary limiting factors, as radiation resources are abundant on the Tibetan Plateau. The optimal temperature for photosynthesis (TAopt) was determined to be 11.92 & DEG;C based on the entire observation dataset, with a maximum photosynthetic capacity (GPPmax) of 0.20 mg CO2 m- 2 s- 1. However, the TAopt and the corresponding GPPmax could be elevated when the soil water content (SWC) was abundant. When SWC exceeded 0.26 m3 m- 3, TAopt increased to 13.41 & DEG;C, and the corresponding GPPmax reached as high as 0.30 mg CO2 m- 2 s- 1, which is the maximum the ecosystem could reach. Thus, the optimal environmental config-uration for photosynthesis that could realistically occur in the natural world in this alpine meadow was air temperature (TA)=13.41 & DEG;C, SWC=0.28 m3 m- 3, vapor pressure deficit (VPD)=0.61 kPa, net radiation (RN)= 411.53 J m- 2 s- 1. According to this study, it could be inferred that within a reasonable range, higher temper-atures and VPD would benefit photosynthesis in this alpine meadow as long as the soil water supply is sufficient. The climate on the Tibetan Plateau is arid with high VPD and is experiencing warming due to climate change. Consequently, alpine ecosystems situated in relatively humid regions with sufficient soil water resources may exhibit greater potential for carbon sequestration than previously estimated. |
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