石羊河流域土壤水分和电导率的空间分布特征

Spatial differentiation of soil moisture and conductivity in Shiyang River Basin

土壤水盐空间分异特征是土壤盐碱化防治与改良的重要依据,也是盐碱地资源开发利用的重要基础。在流域尺度上,综合石羊河流域林地、草地、耕地、盐碱地、荒漠等不同土地利用类型土壤水盐分异特征的研究较少,难以支撑新时期变化环境下盐碱地的改良与利用需求。运用地统计学与传统统计学方法,对石羊河流域土壤水分和电导率的空间分异特征进行了研究,并分析了不同土地利用类型对土壤水盐分布的影响。结果表明:石羊河流域土壤含水量呈现西南高、东部和西部低的趋势,在剖面上由表层的8.75%向深层的10.19%逐渐递增。土壤电导率呈现东南和西南部低、东北和西北部高的趋势,中、重度盐碱化土和盐土的面积占流域总面积的56.55%。不同土地利用类型中,林地土壤平均含水量最高(21.08%),其次为耕地(15.60%)、盐碱地(12.40%)、草地(6.98%)和荒漠(1.60%)。盐碱地土壤平均电导率最高(8.55 dS·m^(-1)),其次为草地(1.28 dS·m^(-1))、荒漠(0.51 dS·m^(-1))、耕地(0.48 dS·m^(-1))和林地(0.18 dS·m^(-1))。土地利用类型对土壤水盐的垂直分布有显著影响,且土壤水分含量与海拔、植被生物量、盖度、密度显著正相关,与容重呈显著负相关。林地和草地的土壤水分含量与电导率相关性不显著,而耕地、盐碱地和荒漠的土壤水分含量和电导率显著正相关,表明从石羊河流域上游到下游,土壤盐分对土壤水分的依赖程度不断增强。

Study on the spatial differentiation of soil water and salt is an important basis for the prevention and improvement of soil salinization,and also an important foundation for the development and utilization of saline land resource.At a watershed scale,relatively few studies have been conducted on the spatial differentiation of soil water and salt under different land-use types such as forest land,grassland,cropland,saline land and desert in the Shiyang River basin,which can hardly support the improvement and utilization needs of saline land under the changing environment in the new period.In this study,the spatial differentiation of soil water and conductivity in the Shiyang River basin were studied using geostatistical and traditional statistical methods,and the effects of different land-use types on soil water and salt distribution were analyzed.The results showed that the soil water content in the Shiyang River basin demonstrated a trend of high in the southwest and low in the east and west,and gradually increased from 8.75%in the surface soil layer to 10.19%in the deep soil layer.Soil conductivity showed a trend of low in the southeast and southwest and high in the northeast and northwest,and the area of moderately and heavily saline and saline soils accounted for 56.55%of the total watershed area.The highest average water content was exhibited in forest soils(21.08%),followed by arable land(15.60%),saline land(12.40%),grassland(6.98%),and desert(1.60%).The highest average soil conductivity was found in saline land(8.55 dS·m^(-1)),followed by grassland(1.28 dS·m^(-1)),desert(0.51 dS·m^(-1)),cropland(0.48 dS·m^(-1))and forest land(0.18 dS·m^(-1)).Land-use type had a significant effect on the vertical distribution of soil water and salt,and soil moisture was significantly and positively correlated with elevation,vegetation biomass,cover,and density,while significantly and negatively correlated with soil bulk density.There was no significant correlation between soil moisture and conductivity in forest land and grassland,while significant positive correlations were detected in cultivated land,saline land and desert showed,indicating that the dependence of soil salinity on soil moisture increased from the upstream to the downstream of Shiyang River basin.