State Key Laboratory of Desert & Oasis Ecology, Xinjiang Institute of Ecology & Geography, Chinese Academy of Sciences, 818 South Beijing Road, Urumqi, 830011, Xinjiang, People's Republic of China.
Grassland Research Institute, Xinjiang Academy of Animal Sciences, Urumqi, 830000, China.
Environ Monit Assess. 2019 Aug 13;191(9):561. doi: 10.1007/s10661-019-7673-z.
Ecosystem water use efficiency (EWUE) is a popular issue in the comprehensive study of climate change, ecology, and hydrology. Currently, views on the response of EWUE to temperature, precipitation, and drought remain controversial. Based on ecosystem net primary productivity (NPP) and evapotranspiration (ET) datasets, both of which were retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) using the Carnegie Ames Stanford approach (CASA) and surface energy balance algorithms for land (SEBAL) models, respectively, this study comprehensively examined the relationship between EWUE and temperature, precipitation, and drought in the Tianshan Mountains of Central Asia. The results showed that EWUE had an obvious temporal change trend in the Tianshan Mountains. The EWUEs of all vegetation types presented an increasing trend in spring and a decreasing trend in autumn. These results led to a phase shift in the annual cycle of EWUE over the years. Compared with 2000 to 2003, from 2012 to 2016, the annual EWUE cycle had advanced by 32 days. Precipitation generally had a negative effect on EWUE, while temperature had an obvious positive effect on EWUE. The EWUE responses to drought for the different vegetation types showed a variety of change trends. With the increase in drought stress, EWUE not only showed a simple upward or downward trend but also showed an upward trend followed by a downward trend or a downward trend followed by an upward trend. EWUE is more sensitive to changing environments than NPP or ET and is more suitable for analyzing ecosystem responses to global change.
生态系统水分利用效率（EWUE）是气候变化、生态学和水文学综合研究中的一个热门问题。目前，关于 EWUE 对温度、降水和干旱的响应的观点仍存在争议。本研究基于生态系统净初级生产力（NPP）和蒸散（ET）数据集，分别使用 Carnegie Ames Stanford 方法（CASA）和地表能量平衡算法陆地模型（SEBAL）从 Moderate Resolution Imaging Spectroradiometer（MODIS）中提取，综合考察了中亚天山地区 EWUE 与温度、降水和干旱的关系。结果表明，EWUE 在天山地区有明显的时间变化趋势。所有植被类型的 EWUE 在春季呈增加趋势，在秋季呈减少趋势。这些结果导致 EWUE 的年循环多年来出现相位变化。与 2000 年至 2003 年相比，2012 年至 2016 年，年 EWUE 周期提前了 32 天。降水通常对 EWUE 有负面影响，而温度对 EWUE 有明显的正效应。不同植被类型对干旱的 EWUE 响应表现出多种变化趋势。随着干旱胁迫的增加，EWUE 不仅表现出简单的上升或下降趋势，还表现出上升趋势后下降趋势或下降趋势后上升趋势。与 NPP 或 ET 相比，EWUE 对变化的环境更为敏感，更适合分析生态系统对全球变化的响应。
