Water use efficiency (WUE) provides vital information about the carbon‐water coupling relationship of a terrestrial ecosystem. Understanding the spatiotemporal variability and driving factors of the Tibetan Plateau (TP) WUE can facilitate the prediction of the response of the carbon‐water process in the TP to climate change. We used a land surface model to investigate spatiotemporal changes in WUE and the responses to environmental factors, such as atmospheric CO₂ concentration and climate and land use change. Our results suggest that the average annual TP WUE was 0.38 g C kg⁻¹ H₂O and that this variable tended to increase at a rate of 0.001 g C kg⁻¹ H₂O year⁻¹ during the period of 1979–2010. Changes in atmospheric CO₂ concentration caused a significant increase in the rate of WUE change (i.e., 0.00051 g C kg⁻¹ H₂O year⁻¹); these changes were also found to most significantly contribute to WUE increase in the TP and account for approximately 51% of the WUE fluctuation. Increasing temperature was found to result in a decreasing WUE (rate: −0.00028 g C kg⁻¹ H₂O year⁻¹). Regarding results on vegetation type, forested areas had the highest WUE (i.e., 0.88 g C kg⁻¹ H₂O) and the highest rate of WUE change (i.e., 0.004 g C kg⁻¹ H₂O year⁻¹), whereas the lowest WUE (i.e., 0.26 g C kg⁻¹ H₂O) was found in steppe and alpine vegetation areas. Although all other vegetation types were associated with increasing WUE, there was no significant change in the WUE of steppe areas. The main factors influencing WUE fluctuation for different vegetation types were found to be atmospheric CO₂ concentration and temperature change.

中文翻译：

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青藏高原水资源利用效率的时空变化及其驱动因素

用水效率（WUE）提供了有关陆地生态系统碳水耦合关系的重要信息。了解青藏高原WUE的时空变异性和驱动因素可以帮助预测TP中碳水过程对气候变化的响应。我们使用土地表面模型调查WUE的时空变化以及对环境因素（例如大气中CO ₂浓度以及气候和土地利用变化）的响应。我们的结果表明，年平均TP WUE为0.38 g C kg ^-1  H ₂ O，并且该变量倾向于以0.001 g C kg ^-1  H ₂ O年^-1的速率增加。在1979年至2010年期间。大气中CO ₂浓度的变化引起WUE变化速率的显着增加（即，0.00051 g C kg ^-1  H ₂ O年^-1）；还发现这些变化对TP中WUE的增加贡献最大，约占WUE波动的51％。发现升高温度导致WUE降低（速率：-0.00028g C kg ^-1  H ₂ O年^-1）。关于植被类型的结果，林区的WUE最高（即0.88 g C kg ^-1  H ₂ O），WUE变化率最高（即0.004 g C kg ^-1  H ₂ O）。O year ^-1），而草原和高山植被区的WUE最低（即0.26 g C kg ^-1  H ₂ O）。尽管所有其他植被类型都与WUE的增加有关，但草原地区的WUE并没有显着变化。发现影响不同植被类型WUE波动的主要因素是大气CO ₂浓度和温度变化。