School of Public Administration, Hohai University, Nanjing, 210098, Jiangsu, China.
School of Ecology and Environmental Science and Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, Yunnan University, Kunming, 650091, China.
Sci Rep. 2020 Nov 20;10(1):20309. doi: 10.1038/s41598-020-77208-6.
Precipitation use efficiency (PUE) is crucial in understanding the coupling between ecosystem carbon and water cycling. In this study, we used a time series (2000-2013) dataset of net primary productivity (NPP) based on the Carnegie-Ames-Stanford Approach (CASA) model together with precipitation to reveal the spatial and temporal patterns of alpine grassland PUE in Northern Tibet. The mean annual PUE values of alpine meadow, alpine meadow steppe, alpine steppe, alpine desert steppe, and alpine desert were 0.48, 0.39, 0.36, 0.29 and 0.23 gc m mm, respectively. The spatial patterns of PUE of alpine grassland demonstrated an initial increase in the arid region and a subsequent decrease in the humid region along the precipitation gradient and peaked at approximately 500 mm. To evaluate the temporal patterns, the sensitivity [Formula: see text] and the Pearson correlation coefficient [Formula: see text] between the PUE and climatic factors were calculated. The inter-annual variability of PUE exhibited a significant negative correlation with annual precipitation (P < 0.05), which implies that NPP had a lower sensitivity to precipitation in most regions. The relationship between PUE and the mean annual temperature is different for different regions. Our findings have an important role in understanding the impacts of precipitation availability on climate change and in the scientific management of the alpine grassland ecosystems.
降水利用效率（PUE）对于理解生态系统碳和水循环的耦合关系至关重要。本研究利用基于卡内基-阿姆斯-斯坦福方法（CASA）模型的净初级生产力（NPP）时间序列（2000-2013 年）数据集和降水数据，揭示了青藏高原高寒草地 PUE 的时空格局。高寒草甸、高寒草甸草原、高寒草原、高寒荒漠草原和高寒荒漠的年平均 PUE 值分别为 0.48、0.39、0.36、0.29 和 0.23 gc m mm。高寒草地 PUE 的空间格局表现为在干旱区先增加，然后在沿降水梯度的湿润区减少，并在约 500 mm 处达到峰值。为了评估时间格局，计算了 PUE 与气候因子之间的敏感性 [Formula: see text] 和 Pearson 相关系数 [Formula: see text]。PUE 的年际变异性与年降水量呈显著负相关（P < 0.05），这意味着在大多数地区，NPP 对降水的敏感性较低。PUE 与年平均温度之间的关系因地区而异。本研究结果对于理解降水供应对气候变化的影响以及高寒草地生态系统的科学管理具有重要意义。
