沙坡头人工固沙植被土壤水分空间异质性

利用传统统计学和地统计学相结合的方法对沙坡头人工固沙植被区0～200 cm 之间的各层土壤水分的空间变异性进行研究.结果表明，1）土壤水分相对变异较大的层是在160～180 cm层和180～200 cm层，变异系数分别为0.72和0.73.表层0～5 cm层的相对变异也较大，变异系数为0.662）半方差函数分析结果表明，各层土壤水分均具有明显的空间变异性，各层土壤水分自相关部分的空间异质性占总空间异质性的程度很高，所占比例在87.7%～99.9%范围内.各层土壤水分的有效变程大小有较大差异，最小值出现在60～80 cm层(7.04 m)，最大值出现在20～40 cm层(19.71 m)，土壤水分有效变程从表层到深层没有明显的变化规律；3）土壤水分插值图反映出0～140 cm之间相邻各层土壤水分变化较大，140～200 cm各层土壤水分变化较小；4）土壤水分在0°、45°、90°、135°四个方向的半方差函数基本上是一条直线，表明在这四个方向上半方差和距离的相关性较低，土壤水分变化是独立、随机的，是同质性的.

Spatial heterogeneity of soil moisture in Shapotou sand-fixing artificial vegetation area

To explore the characteristics of soil moisture heterogeneity in sand-fixing artificial vegetation area is of significance in vegetation recovery and environment control in arid regions. With the methods of traditional statistics and geo-statistics, this paper studied the heterogeneity of soil moisture in the layers from 0 to 200 cm in depth in Shapotou sand-fixing vegetation area. The results showed that the variation of soil moisture in layers of 160 to approximately 180 and 180 to approximately 200 cm was relatively larger, with the variation coefficient being 0.72 and 0.73, respectively, and the next was in top layer (0 to approximately 5 cm ), with a variation coefficient of 0.66. Semi-variance analysis showed that the autocorrelation of soil moisture spatial heterogeneity in total spatial heterogeneity was high, ranging from 87.7% to 99.9%. The scale of spatial heterogeneity in different soil layers was different, with the minimum in 60 to approximately 80 cm layer and the maximum in 20 to approximately 40 cm layer, but no regular changes being observed from surface to deep layers. The colorful contour maps of Kriging interpolation indicated that the variation of soil moisture was larger in 0 to approximately 140 cm layer than in 140 to approximately 200 cm layer. The correlation between semi-variance and distance in four directions of 0 degrees, 45 degrees ,90 degrees and 135 degrees was weak, suggesting that the variation of soil moisture was independent, random, and homogeneous.