黄土高原区域尺度土壤水分空间变异性

Spatial variability of soil moisture at a regional scale in the Loess Plateau

土壤水分是黄土高原植物生长发育和生态环境重建的主要限制因子。为揭示黄土高原区域尺度深层土壤水分的空间变异性,在黄土高原共布点234个,采集深剖面土壤水分样品12 198个。采用经典统计和地统计学相结合的方法系统分析了土壤水分的分布规律、变异特征及影响因素。结果表明:①黄土高原地区土壤水分在水平方向上表现出由东南向西北递减,在垂直方向上(0～500 cm)表现出先减小后增加的分布特征;②土地利用对区域尺度土壤水分的数量及垂直分布规律具有显著影响;③土壤水分在不同土层深度(0～500 cm)的变异系数、空间异质比等参数的垂直分布均呈先减小后增加趋势,这些参数在表达土壤水分变异的效果上具有一致性。相关结果对黄土高原区域尺度水土过程调控、生态水文过程研究具有一定参考价值。

Soil moisture （SM） is one of the key factors for plant growth and eco-environment reconstruction on the Loess Plateau of China. To ascertain the spatial variability of SM in deep soil layers at a regional scale, 234 sampling sites were located with a GPS receiver, and 12 198 soil samples were collected with a soil auger before the rainy season in 2008. The distribution and variation characteristics of SM were evaluated by using classic statistical and geostatistical methods. Results showed that （1） SM decreased gradually from southeast to northwest in the horizontal direction, while in vertical direction, SM decreased from 0 to 90 cm and then increased from 90 to 500 cm soil depth. （2） Land use had a significant impact on the amount and profile distribution of SM. （3） The coefficients of variation and nugget ratios of SM at different depths in 0 - 500 cm profile demonstrated a decreasing-increasing trend, and these indices showed a good consistency in expressing the variation of SM. Understanding this information is beneficial to the management/mediation of soil and water processes, and to the restoration of eco-environment on the Loess Plateau.