The profile distribution of the

The interactive effects of the related factors help to explain the different spatial variability observed in the three ACT-132577 layers. In the 0–60 cm layer, the impacts of elevation and clay content on the spatial variation of SWC differed, increased (Fig. 7) and decreased (Fig. 8) with increasing soil depth, respectively. These different roles in controlling the spatial variation resulted in relative uniformity of SWC within this soil layer. In addition, the 0–60 cm soil layer corresponds to the active root zone in which the vegetation tends to uptake water held in the soil at the highest potentials at faster rates than that held at lower potentials. This phenomenon leads to the distribution of SWC within the rooting depths becoming more uniform among locations (Biswas and Si, 2011). Thus, the vegetation can reduce the spatial variability of SWC that would otherwise be greater if it resulted from the heterogeneity of the topography (Hawley et al., 1983) and texture (Tallon and Si, 2004) alone. Thus, the relatively constant spatial variability of SWC in the first layer resulted from the interaction among the factors of elevation, clay content, and vegetation.