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

采用盆栽控水的方法，研究干旱胁迫（80%FC、60%FC、40%FC和20%FC）及施氮（N0 0 g·pot-1、Nl 1.2 g·pot-1、Nm 3.6 g·pot-1和Nh 6.0 g·pot-1）对麻疯树幼苗叶、茎和根部主要渗透调节物质积累的影响.结果表明： 干旱胁迫条件下，麻疯树幼苗茎和根部的游离脯氨酸、可溶性蛋白和茎部可溶性糖大量积累，叶片中脯氨酸含量也随干旱胁迫程度的增加大幅度上升；Na+、Ca2+和Mg2+在麻疯树幼苗叶、茎和根中大量积累，而K+仅在茎中大量积累，叶片和根部K+含量略微上升.施氮对植株渗透调节物质的影响与干旱胁迫强度和施氮水平有关.在80%FC和60%FC水分条件下，增加N肥施用量能明显促进麻疯树幼苗各组分渗透调节物质的积累；在40%FC水分条件下，Nh处理对渗透调节物质积累的促进作用减弱；而在20%FC条件下，Nl处理植株的渗透调节能力较高，Nm和Nh处理对植株渗透调节的促进作用不明显甚至转为抑制.

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

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.