Interannual and seasonal variability in evapotranspiration of alpine meadow in the Qinghai-Tibetan Plateau
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ORIGINAL PAPER
Interannual and seasonal variability in evapotranspiration of alpine meadow in the Qinghai-Tibetan Plateau Hong Zhang 1 & Ruiyin Dou 2 Received: 7 June 2020 / Accepted: 11 September 2020 / Published online: 16 September 2020 # Saudi Society for Geosciences 2020
Abstract Alpine meadow ecosystem is the major component of the Qinghai-Tibet Plateau (QTP); however, the temporal variations in evapotranspiration (ET) and the underlying drivers still remain poorly understood under the intensified warming and wetting climate. This study explored the different responses of ET to driving factors for alpine meadow in northeastern QTP at daily, seasonal, and yearly scales with the measurements of water fluxes using eddy-covariance techniques between 2013 and 2017. Pearson correlation and stepwise regression methods were used to ascertain the environmental controls of ET and clarify the factors causing the differences in ET among the different seasons and years. The results indicated that mean annual ET was 689, 644, 664, 586, and 691 mm in 2013, 2014, 2015, 2016, and 2017 respectively, in the studied alpine meadow ecosystem. There was a clear consistent seasonal variation pattern for daily ET and climatic factors of net radiation, air temperature, air relative humidity, wind speed, vapor pressure deficit (VDP), and precipitation. Net radiation had a significant effect on variation of daily ET during all seasons. The findings of the study highlighted that higher variations in ET existed in daily, seasonal, and annual scales, we found VDP exerted significantly positive effects on variations in ET in non-growing seasons and drought year, suggesting that alpine meadow ecosystem is sensitive to VDP and becoming increasing vulnerable to atmospheric drought under warming climate. The soil moisture had positive effects on ET and the effect became stronger after drought. The 2015/2016 El Niño event caused little change in ET due to extreme nocturnal warming. These results provide new insights on the response of alpine meadow ET to climate warming, which may facilitate the modeling of water cycle of alpine meadow ecosystem. Keywords Alpine vegetation . Evapotranspiration . Soil water content . Drought . Eddy-covariance . Cold region
Introduction Evapotranspiration (ET) is a key component of water budget in terrestrial ecosystems (Burba and Verma 2005). Accurate estimation of this element is important in scientific water management in arid and semiarid regions (Dinpashoh and Babamiri 2020). However, ET is very difficult to precisely quantify (Shuttleworth 2008). Understanding of interannual Responsible Editor: Broder J. Merkel * Ruiyin Dou [email protected] Hong Zhang [email protected] 1
Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
2
School of Economics and Resource Management, Beijing Normal University, Beijing 100875, China
and seasonal variability in evapotranspiration is important for clarifying underlying drivers for the heat and water exchange between land surface and
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