云雾山草坡和泾川刺槐林坡面土壤电阻率和含水率的空间差异

Spatial differences of soil electrical resistivity and moisture content in slope grassland in Yunwu Mountains and in slope locust forestland in Jingchuan Mountains, Northwest China

为了解黄土区不同植被类型坡面土壤水分的空间分布,选择固原云雾山和泾川官山于2010年5月初采用多电极电阻仪法(ERT)在长约400m的坡面上设置纵向样线,并多点同步连续测定土壤含水率和电阻率。结果表明:云雾山土壤电阻率和含水率的相关性较好(Y=39.596e-0.0075x,R2=0.78),说明通过测定坡面电阻率推求土壤水分的坡面变化是可行的。云雾山电阻率沿坡面表现为坡上(308.5Ωm)至坡中(360.44Ωm)逐渐增大,到坡下部又逐渐减小(318.75Ωm);而泾川刺槐林坡面从坡上到坡下电阻率逐渐减小,且云雾山草坡含水率要大于泾川刺槐林。云雾山草坡在1～3m土层出现轻度干层,3～4m深度出现中度干层,6～17m出现重度干层;泾川刺槐林在3m土层出现轻度干层,6m深度出现中度干层,在≥10m层出现重度干层。

In order to understand the spatial distribution of soil moisture along the slopes with different vegetation types on Loess Plateau, a longitudinal line transect was installed on a 400-m long slope in Yunwu Mountains at Guyuan and in Guanshan Mountains at Jingchuan in early May 2010, respectively, and the method of multi-electrode electrical resistivity tomography （ERT） was adopted to measure the soil electrical resistivity and moisture content by points simultaneously and continuously. There was a good correlation （Y=39.596e-0.0075x, R2=0.78） between the soil electrical resistivity and moisture content in the slope grassland in Yunwu Mountains, suggesting that it would be feasible to ascertain the spatial variation of soil moisture on grass slope through measuring the spatial distribution of soil electrical resistivity. In Yunwu Mountains, the soil electrical resistivity increased gradually from slope top （308.5 Ωm） to slope middle （360.44 Ωm）, and then decreased （318.75 Ωm） on slope bottom; while in Guanshan Mountains, the soil electrical resistivity decreased gradually from slope top to slope bottom. The soil moisture content on the grass slope in Yunwu Mountains was higher than that on the locust forest slope in Guanshan Mountains. On the grass slope in Yunwu Mountains, the light, mild, and severe dry soil layers occurred at the depths 1-3 m, 3-4 m, and 6-17 m soil layers; while on the locust forest slope in Guanshan Mountains, the light, mild, and severe dry soil layers occurred at the depths 3 m, 6 m, and ≥10 m, respectively.