晋西北黄土丘陵区土壤饱和导水率的空间分布特征及影响因素

土壤饱和导水率（K_s）是反映土壤入渗性能与土壤持水能力的重要参数,为探究流域尺度下土壤K_s的空间分布特征及影响因素,更好地掌握土壤水文过程与调节机理,选取晋西北黄土丘陵区朱家川流域横向梯度（上游、中游、下游）不同土地利用方式下的土壤（70个样点）为研究对象,采用定水头法测定土壤K_s,并获取样点地形因子和其他土壤理化性质,通过建立土壤K_s偏最小二乘回归模型（PLSR）,分析影响土壤K_s空间分布格局的主要因素。结果表明：（1）除土壤容重和砂粒含量为弱变异外,区域土壤理化性质其余因子均为中等变异;土壤K_s在横向梯度下表现为上游 > 中游 > 下游;（2）不同土地利用方式下土壤K_s差异显著（P<0.05）,由高到低顺序为林地 > 农地 > 草地;（3）林地（VIP=1.997）与草地（VIP=1.710）利用方式、土壤容重（VIP=1.548）、土壤有机质（VIP=1.323）、大团聚体（VIP=1.266）、粉粒含量（VIP=1.062）和黏粒含量（VIP=1.049）是土壤K_s变化的主要因素,林地利用方式影响程度最大。土地利用、土壤性质、地形因子均是影响黄土丘陵区土壤K_s空间分布的主要因素,是用来模拟预测土壤K_s空间分布的重要因子。

Spatial Distribution Characteristics and Influencing Factors of Soil Saturated Hydraulic Conductivity in the Loess Hilly Region of Northwestern Shanxi

Soil saturated hydraulic conductivity (K_s) is an important parameter reflecting soil infiltration performance and soil water holding capacity. Understanding the spatial distribution characteristics and influencing factors of soil K_s at the watershed scale is helpful to better comprehend soil hydrological processes and regulation mechanisms. Totally 70 soil samples were collected from different land use patterns in the horizontal gradients (upstream, midstream, downstream) of the Zhujiachuan watershed in the Loess Hilly Region of Northwestern Shanxi. The soil K_s was determined by constant-head method, the topographical factors and physical and chemical properties of the sample points were also measured to establish partial least-squares regression model of soil K_s, and then the main factors affecting the spatial distribution pattern of soil K_s were analyzed. The study showed that: (1) Soil bulk density and sand content showed a weak variation, but the other physical and chemical properties showed the moderate variations. The soil K_s performance in the horizontal gradients was upstream > midstream > downstream; (2) Soil K_s varied greatly with different land uses (P<0.05), the sequence was forest land > agricultural land > grassland; (3) Forest land (VIP=1.997), grassland (VIP=1.710), soil bulk density (VIP=1.548), soil organic content (VIP=1.323), macro-aggregates (VIP=1.266), silt content (VIP=1.062) and clay content (VIP=1.049) were the main factors influencing soil K_s, among which the use of forest land gave the greatest impact. Land use, soil properties and topographical factors were the main factors affecting the spatial distribution of soil K_s in the Loess Hilly Region and could be used to simulate and predict the spatial distribution of soil K_s.