The Qinghai-Tibetan Plateau (QTP) is generally considered to be the water source region for its surrounding lowlands. However, there have only been a few studies that have focused on quantifying alpine meadow evapotranspiration (ET) and its partitioning, which are important components of water balance. This paper used the Shuttleworth–Wallace (S–W) model to quantify soil evaporation (E) and plant transpiration (T) in a degraded alpine meadow (34°24′ N, 100°24′ E, 3963 m a.s.l) located at the QTP from September 2006 to December 2008. The results showed that the annual ET estimated by the S–W model (ET_SW) was 511.5 mm (2007) and 499.8 mm (2008), while E estimated by the model (E_SW) was 306.0 mm and 281.7 mm for 2007 and 2008, respectively, which was 49% and 29% higher than plant transpiration (T_SW). Model analysis showed that ET, E, and T were mainly dominated by net radiation (R_n), while leaf area index (LAI) and soil water content at a 5 cm depth (SWC_5cm) were the most important factors influencing ET partitioning. The study results suggest that meadow degradation may increase water loss through increasing E, and reduce the water conservation capability of the alpine meadow ecosystem.

中文翻译：

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青藏高原三河源区高寒草甸蒸散及其分区

青藏高原（QTP）通常被认为是其周围低地的水源区。然而，只有少数研究专注于量化高山草甸蒸散量 ( ET ) 及其分配，这是水平衡的重要组成部分。本文所使用的沙特尔沃思-华莱士（S-W）模型对此进行量化土壤蒸发（ë）和植物蒸腾（Ť）在退化草甸（34°24'N，100°24'E，3963米ASL）位于2006 年 9 月至 2008 年 12 月的 QTP。 结果表明S-W 模型估计的年ET（ET _SW）为 511.5 mm（2007）和 499.8 mm（2008），而E模型估计的2007 年和 2008 年( E _SW ) 分别为 306.0 mm 和 281.7 mm，分别比植物蒸腾作用 ( T _SW )高 49% 和 29% 。模型分析表明，ET，ê，和Ť主要由净辐射（主导ř _Ñ），而叶面积指数（LAI），并在5厘米深（土壤含水量SWC _5厘米）是影响的最重要因素ET分区。研究结果表明，草地退化可能通过增加E, 降低高寒草甸生态系统的节水能力。