拉萨河谷灌丛草原与农田水热平衡 及植被水分利用特征

doi:10.11821/xb200903005

摘要/Abstract

摘要：

以青藏高原的拉萨河谷下游的灌丛草原和农田为研究对象，在中国科学院拉萨高原生态试验站的农田与附近的灌丛草原开展实验，利用SHAW 模型模拟了2004 年10 月-2005 年 9 月灌丛草原与农田水热平衡以及根系吸水过程。模拟结果经分析得出， (1) 农田所接收的净辐射比灌丛草原要多，农田接收的能量大部分以潜热形式支出，全年的波文比为0.29；而灌丛草原的波文比为0.89。灌丛草原全年的潜热通量是农田的53%，具有一定的抑制蒸散发的功能。(2) 农田耗水量是灌丛草原的1.8 倍。农田由于大量的灌溉造成较大的渗漏损失，同时也增加了土壤蒸发这一无益损耗。(3) 深层土壤水向上的补给与根系吸水两方面的模拟都表明，灌丛草原的植被比农田能更大程度地利用深层土壤水。

关键词: 拉萨河谷, 灌丛草原, 农田, SHAW 模型, 水热平衡, 根系吸水

Abstract:

More and more natural vegetation land has been transformed into crop fields in the Lhasa river valley on the Tibetan Plateau with the local population growth and economic development. However, the land cover changes would exert great impact on ecosystems energy and water balance and water use. We did experiments in crop fields at Lhasa Plateau Ecosystem Research Station and the nearby shrub grassland. Then we researched the water and energy balance and the processes of water extraction from roots using SHAW model based on experiment data and climatic data obtained at Lhasa Plateau Ecosystem Research Station. By the analysis of the simulated results, some main conclusions were drawn as follows. (1) Net radiation received by crop fields was more than shrub grassland; and the outgoing latent heat from crop fields was dominating, with the all-year Bowen ratio being 0.29. As for the shrub grassland, the all-year Bowen ratio was 0.89. The outgoing latent heat of shrub grassland was 53% of crop fields. Thus, shrub grassland limited evapotranspiration to some extent. (2) The water consumed of crop fields was nearly twice of that of shrub grassland. Irrigation resulted in much deep percolation and increased soil evaporation. (3) The deep soil water supply and root extraction indicated that shrubs could absorb deep soil water that could not be used by crops.

Key words: Lhasa river valley, shrub grassland, crop fields, SHAW model, water and heat balance, root extraction

尹志芳,欧阳华,徐兴良,宋明华,段德玉,张宪洲. 拉萨河谷灌丛草原与农田水热平衡及植被水分利用特征[J]. 地理学报, 2009, 64(3): 303-314.

YIN Zhifang,OUYANG Hua,XU Xingliang,SONG Minghua,DUAN Deyu,ZHANG Xianzhou. Water and Heat Balance and Water Use of Shrub Grassland and Crop Fields in Lhasa River Valley[J]. Acta Geographica Sinica, 2009, 64(3): 303-314.

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