晋西黄土区林地坡面土壤水分异质性研究

Heterogeneity of soil moisture and its influencing factors on forest land in the loess hilly areas

经过多年观测,研究了晋西黄土区林地坡面土壤水分异质性的变化规律,通过不同数学方法分析土壤水分与环境因子的关联,探讨坡面尺度上的土壤水分空间异质性的影响因子。结果表明,晋西黄土区林地坡面土壤含水量呈现出明显的剖面与时间变化规律;土壤平均含水量在100cm以内,从表层开始随着土层深度的增加而减少,变异系数也相应减小;土壤含水量与前期降雨呈现出显著的线性关系;变异系数在降雨后迅速减小,并随着干旱天数的增加而增加。通过灰色关联与多元回归分析得出在坡面尺度上土壤水分是地形因子、植被因子等多重因子共同作用的结果,对于不同土层土壤水分来说,影响因素所起的作用也不相同。在坡面尺度上气象因子对土壤水分的空间异质性影响不大。

The degree of spatial heterogeneity of soil moisture and its influential environmental factors were studied in Chaijiachuan watershed in the loess hilly areas in west Shanxi province. Soil moisture measurement were performed every half-month at five layers of soil profile (0~20, 20~40, 40~60, 60~80, 80~100 cm) from April to September, 2002. The results indicate that the soil moistare content on the sloping forest lands varies remarkably among different layers. As the increasing of soil depth, the mean moisture content decreases significantly, and the heterogeneity exhibits a decreasing trend. The temporal changes of the mean moisture and the heterogeneity are also obvious. The mean moisture increases after precipitation events and henceforth it declines as the soil dries down, whilst the heterogeneity exhibits an opposite pattern. The spatial heterogeneity of soil moisture are influenced by the multiple environmental attributes at slope scale. However, the relative roles of different environmental attributes vary with soil depths and with seasonal evolution.