Evapotranspiration and water balance of high-elevation grassland on the Tibetan Plateau
Evapotranspiration and water balance of high-elevation grassland on the Tibetan Plateau
复制标题
DOI：
10.1016/j.jhydrol.2015.12.021
复制
发表时间：
2016-02-01
影响因子：
6.4
通讯作者：
Leuschner, Christoph
中科院分区：
文献类型：
--
作者：
Coners, Heinz;Babel, Wolfgang;Leuschner, Christoph
高海拔草原莎草科矮嵩草覆盖近50万公里（2）的青藏高原。作为气候变化的结果，在这个季风影响区的降水模式可能会改变草地生产力的可能后果。然而，人们对这个世界第二大高山生态系统中的水循环知之甚少。本文对海拔4400 m的高海拔嵩草草地系统蒸散量进行了测定。在东南部的高原在两个夏天使用三种不同的方法，可称重的微蒸渗仪，涡度相关测量，和水平衡模拟与土壤-植物-大气传输模型SEWAB。三种方法之间的一致性很好，我们发现在潮湿的夏季（6月至8月）ET率为4-6 mm d（-1），在干燥期接近2 mm d（-1），尽管海拔高，叶面积指数仅接近1。测得的ET率与海拔1500-2500 m的高山草原报告的ET率相当。在温带山区，也匹配ET率管理的低地草原在温带。在研究现场与430毫米的年降水量，低夏季降雨量减少ET显着和渗透到底土只发生在潮湿的时期。我们的研究结果表明，在4400米的高海拔草原的蒸散量可以高达低地草原，尽管大海拔变化的非生物和生物的驱动程序ET，和周期性缺水可能会影响大部分的西藏嵩草牧场。(C)2015爱思唯尔B. V.保留所有权利。
High-elevation grasslands of the Cyperaceae Kobresia pygmaea cover nearly half a million km(2) on the Tibetan Plateau. As a consequence of climate change, precipitation patterns in this monsoon influenced region may change with possible consequences for grassland productivity. Yet, not much is known about the water cycle in this second largest alpine ecosystem of the world. We measured the evapotranspiration of a high-elevation Kobresia pasture system at 4400 m a.s.l. in the south-eastern part of the plateau in two summers using three different approaches, weighable micro-lysimeters, eddy covariance measurements, and water balance modeling with the soil-plant-atmosphere transfer model SEWAB. In good agreement among the three approaches, we found ET rates of 4-6 mm d(-1) in moist summer periods (June-August) and similar to 2 mm d(-1) in dry periods, despite the high elevation and a leaf area index of only similar to 1. Measured ET rates were comparable to rates reported from alpine grasslands at 1500-2500 m a.s.l. in temperate mountains, and also matched ET rates of managed lowland grasslands in the temperate zone. At the study site with 430 mm annual precipitation, low summer rainfall reduced ET significantly and infiltration into the subsoil occurred only in moist periods. Our results show that the evapotranspiration of high-elevation grasslands at 4400 m can be as high as in lowland grasslands despite large elevational changes in abiotic and biotic drivers of ET, and periodic water shortage is likely to influence large parts of the Tibetan Kobresia pastures. (C) 2015 Elsevier B.V. All rights reserved.