Energy partitioning over a semi-arid shrubland in northern China
Energy partitioning over a semi-arid shrubland in northern China
复制标题
中国北方半干旱灌丛的能量分配
DOI：
10.1002/hyp.10685
复制
发表时间：
2016-03-15
影响因子：
3.2
通讯作者：
Peltola, H.
中科院分区：
文献类型：
--
作者：
Jia, X.;Zha, T. S.;Peltola, H.
在过去的十年里，中国北部分布广泛的灌木丛已经显示出明显的从荒漠化中恢复的迹象，这是广泛保护措施的结果。然而，为了支持目前在保护方面的努力，需要更多关于表面能量分配及其生物物理控制的知识。利用2012年在中国西北部半干旱灌丛上进行的涡旋协方差测量，我们研究了地表能量平衡分量在日尺度和季节尺度上的变化，以及生物物理因素如何控制地表参数和能量交换。在一年的大部分时间里，感热通量(H)超过潜热通量(E)，导致年鲍文比(H/E)为2.0。叶面积指数(LAI)的季节高峰与降雨频繁同时出现时，E仅在盛夏时超过H。蒸散量日最大值为3.3 mm/d(-1)，总和为283 mm/d(-1)。蒸发率(EF，即E/R-n)、Priestley-Taylor系数()、表面电导(g(S))和解偶系数()均与土壤含水率和叶面积指数呈显著正相关。高蒸气压亏差(Vpd)对E的直接增强被g的同时抑制(S)所缓冲。G(S)通过调节LAI、SWC和VPD的作用，发挥直接控制EF的作用。我们的结果强调了植物对缺水的适应性反应在调节生态系统能量分配方面的重要性，并表明植被重建在扭转半干旱地区荒漠化的过程中发挥了重要作用。版权所有(C)2015 John Wiley&Sons，Ltd.
During the last decade, the widely distributed shrublands in northern China have shown significant signs of recovery from desertification, the result of widespread conservation practices. However, to support the current efforts in conservation, more knowledge is needed on surface energy partitioning and its biophysical controls. Using eddy-covariance measurements made over a semi-arid shrubland in northwest China in 2012, we examined how surface energy-balance components vary on diurnal and seasonal scales, and how biophysical factors control bulk surface parameters and energy exchange. Sensible heat flux (H) exceeded latent heat flux (E) during most of the year, resulting in an annual Bowen ratio (, i.e. H/E) of 2.0. E exceeded H only in mid-summer when frequent rainfall co-occurred with the seasonal peak in leaf area index (LAI). Evapotranspiration reached a daily maximum of 3.3mmday(-1), and summed to 283mmyr(-1). The evaporative fraction (EF, i.e. E/R-n), Priestley-Taylor coefficient (), surface conductance (g(s)) and decoupling coefficient () were all positively correlated with soil water content (SWC) and LAI. The direct enhancement of E by high vapour pressure deficit (VPD) was buffered by a concurrent suppression of g(s). The g(s) played a direct role in controlling EF and by mediating the effects of LAI, SWC and VPD. Our results highlight the importance of adaptive plant responses to water scarcity in regulating ecosystem energy partitioning, and suggest an important role for revegetation in the reversal of desertification in semi-arid areas. Copyright (c) 2015 John Wiley & Sons, Ltd.