基于CT扫描研究青海湖流域高寒草甸不同坡位土壤大孔隙结构特征

以青海湖流域的高寒草甸土壤为研究对象,对该高寒草甸的坡上、坡中和坡下土壤分别取原状土柱进行CT扫描,利用Fiji软件分析土壤大孔隙结构特征的差异。结果表明:坡位对土壤的大孔隙结构有较大影响,坡上土壤的大孔隙数量、大孔隙度和大孔隙等效直径均大于坡中土壤,坡中土壤的大孔隙参数大于坡下土壤,坡上土壤的平均大孔隙度是坡中和坡下土壤的15.5和46.5倍。坡上土壤的大孔隙主要分布在150~400 mm土层深度,而坡中土壤的大孔隙主要分布在0~150 mm深度,坡下土壤的大孔隙主要在0~200 mm深度分布。坡上和坡中土壤的大孔隙形成主要是在土壤团聚体的作用下形成,植物根系在坡下土壤的大孔隙形成中占主导作用。

Soil Macropores of Alpine Kobresia Meadow in Different Slope Positions in the Qinghai Lake Watershed

The objective of this study is to quantify macropore structures of Alpine Kobresia meadow soils in different slope positions in the Qinghai Lake Watershed. A total of nine soil cores (0–50 cm deep) were taken respectively at the upper-slope, mid-slope and lower-slope sites with 3 replicates in each site, and the cores were scanned with a GE HISPEED FX/I medical scanner. Numbers of macropores, macroporosities and macropore equivalent diameters were interpreted by using X-ray computed tomography. The results indicated that slope position could significantly influence soil macropores. Soils on upper-slope had greater macroporosity, deeper and longer macropores than other two sites. Macroporosity was 15.5–46.5 times greater in soils on upper-slope than other two sites, and macropores were distributed mainly in the 150–400 mm layer, but mainly in the 0–150 mm and 0–200 mm soil layer in the mid-slope and the lower-slope, respectively. The form of macropores in lower slope can be attributed to root growth and decay, while can be attributed to aggregate function in the upper and middle slopes.