|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|6410553||1629919||2016||10 صفحه PDF||سفارش دهید||دانلود رایگان|
- Evapotranspiration at high elevations was measured with three independent approaches.
- Eddy covariance, micro-lysimeters and modeling gave similar results.
- Grassland ET was remarkably high at 4400Â m a.s.l.
- ET was largely dependent on soil moisture.
- Drought plays an important role on the Tibetan Plateau.
SummaryHigh-elevation grasslands of the Cyperaceae Kobresia pygmaea cover nearly half a million km2 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 4400Â 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 4-6Â mmÂ dâ1 in moist summer periods (June-August) and â¼2Â mmÂ dâ1 in dry periods, despite the high elevation and a leaf area index of only â¼1. Measured ET rates were comparable to rates reported from alpine grasslands at 1500-2500Â 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 430Â 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 4400Â 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.
Journal: Journal of Hydrology - Volume 533, February 2016, Pages 557-566