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通过对降雨再分配,荒漠灌丛可改变降雨在灌丛内的水平空间分布,进而影响植被冠层下土壤水分的空间响应.本文以腾格里沙漠东南缘人工植被区柠条和油蒿灌丛为研究对象,分析了灌丛干扰下的降雨再分配过程及灌丛下土壤水分的空间响应.结果表明:柠条和油蒿灌丛的穿透水、树干茎流分别占降雨量的74.4%、11.3%和61.8%、5.5%.次降雨过程中,柠条和油蒿穿透水空间变异性均较大,平均变异系数分别为0.25和0.30;由于可以将更多的降雨以树干茎流形式在根部富集,柠条主干基部土壤湿润锋深度明显比冠层其余位置深,而油蒿仅在大降雨事件时才较为明显.灌丛对降雨的再分配作用改变了降雨达到地表时的空间分配,致使冠层下土壤湿润锋深度呈现明显的不均一性.
Through the redistribution of rainfall, the desert shrub can change the horizontal spatial distribution of rainfall within the shrub, and then affect the spatial response of soil moisture under the vegetation canopy.This paper studied the spatial response of soil moisture under artificial vegetation in the southeastern margin of Tengger Desert, The results showed that the penetrating and stem-stem flow of Caragana korshinskii and Artemisia ordosica shrub respectively accounted for 74.4% of the rainfall %, 11.3% and 61.8%, 5.5% respectively.The spatial variability of Caragana korshinskii and Artemisia ordosica penetration water was greater during the sub-rainfall with the average coefficient of variation of 0.25 and 0.30, respectively. The flow patterns were enriched in the roots, and the depths of soil wetting fronts in the roots of C. korshinskii were significantly deeper than those in the rest of the canopy, while A. ordosica was only evident during heavy rains. The redistribution of rainfall to the shrubs changed the effect of rainfall on the surface The spatial distribution of soil moisture caused a significant heterogeneity in the depth of soil moist front under the canopy.