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对近些年提出的两种生态系统水分利用效率指标——内在水分利用效率(IWUE)和固有水分利用效率(u WUE)与经典的水分利用效率(WUE)指标在黄土高原典型半干旱草地生态系统的应用情况进行了比较,主要分析了不同指标在小时、日和年尺度上的一致性和稳定性,并提出优化水分利用效率(o WUE)指标,比较了不同定义的水分利用效率指标在模拟总初级生产力(GPP)逐日动态过程上的表现。结果显示:IWUE和u WUE适合在日和小时尺度分析植被的碳水耦合特征,WUE适合分析年尺度的碳水耦合特征;o WUE指标在描述碳水耦合特征方面与u WUE相比并没有本质性改善,但在用于模拟GPP动态过程时模拟效果改善明显;采用o WUE和u WUE指标能改善植被生长盛期的GPP动态过程模拟,但在生长季早期和晚期的模拟效果比WUE差。IWUE指标不适合模拟GPP动态过程。
In this paper, two indicators of water use efficiency (IWUE), intrinsic WUE (water use efficiency) and WUE (water use efficiency) of two typical ecosystems proposed in recent years are studied in typical semi-arid grassland ecological system This paper mainly analyzes the consistency and stability of different indicators on the hour, day and year scales, and puts forward the optimal WUE (o wUE) index. The different definitions of water use efficiency index Simulation of gross primary productivity (GPP) daily dynamic performance. The results show that: IWUE and uWUE are suitable for analyzing the coupling characteristics of vegetation on the day and hour scales, and WUE is suitable for analyzing the coupling characteristics of the annual scale; o WUE index has no essential improvement compared with uWUE in describing the coupling characteristics of water. However, the simulation results improved obviously when used to simulate GPP dynamic process. The GPP dynamic process simulation which can improve the vegetation growth duration with o WUE and u WUE indexes was worse than WUE in the early and late growing season. IWUE indicators are not suitable for simulating GPP dynamics.