黄土丘陵区典型植被土壤物理性质差异及其对导水特性影响

Differences in Soil Physical Properties of Typical Vegetation in Loess Hilly Region and Effects on Water Conductivity

选取黄土丘陵区12种典型植被样地,通过测定各样地不同土层植物残体生物量、土壤容重、毛管孔隙度、非毛管孔隙度及饱和导水率,研究各指标随土层深度和植被类型的变化规律及其对土壤饱和导水率的影响。结果表明:(1)除容重随土层深度增加外,植物残体、毛管孔隙度、非毛管孔隙度和饱和导水率均随土层深度减少,其中植物残体大多集中于表层土壤(0—10 cm),占总残体生物量的51.4%~85.7%。(2)不同植被类型其植物残体及土壤物理性质存在显著差异,乔木林地植物残体、农耕地土壤容重、灌木林地非毛管孔隙度及饱和导水率均最大,而毛管孔隙度与不同土地利用类型间无显著差异。(3)饱和导水率随植物残体生物量密度(0—10 cm)和土壤容重呈幂函数减小,随毛管孔隙度和非毛管孔隙度呈幂函数增大;土壤容重(BD)和非毛管孔隙度(NCP)是影响土壤饱和导水率(Ks)的主要因素,且土壤饱和导水率可表示为两者的综合非线性方程(Ks=0.6BD^-4.717NCP^0.203,P<0.01,R^2=0.63,NSE=0.50)。此外,沙棘灌木林地平均饱和导水率最大,有利于降雨过程中土壤水分入渗,具有较强的水土保持功能。本研究结果可为黄土高原植被恢复生态水文效益评价提供理论依据。

In this study, soils from the sites of 12 vegetation plots were sampled, and plant residue, soil bulk density, capillary porosity, non-capillary porosity and saturated hydraulic conductivity were measured to discuss their variations in different soil layers and vegetation types. Besides, the effects of plant residue and soil properties on the saturated hydraulic conductivity were detected. The results showed that: (1) Soil bulk density increased with the increase of soil depth, while plant residue, capillary porosity, non-capillary porosity and saturated hydraulic conductivity decreased. Plant residue mainly existed in the top soil of 0—10 cm, which accounted for 51.4% to 85.7% of the total plant residue. (2) Soil properties and plant residue differed from vegetation types. In general, forest had the largest plant residue, cropland had the highest soil bulk density, and shrub land had the maximum non-capillary porosity and saturated hydraulic conductivity. While no significant difference of capillary porosity was found between different land use types. (3) Saturated hydraulic conductivity decreased with the plant residue (0—10 cm) and soil bulk density, while increased with capillary porosity and non-capillary porosity. Soil bulk density (BD) and non-capillary porosity (NCP) were key factors that affect the soil saturated hydraulic conductivity (Ks), which would simulated saturated hydraulic conductivity as a nonlinear function (Ks=0.6BD^-4.717NCP^0.203, p<0.01, R^2=0.63, NSE=0.50). Moreover, the shrub land of Hippophae rhamnoides L. had the maximum value of saturated hydraulic conductivity, which would promote the ability of water infiltration during the precipitation and thus had a great effect on soil and water conservation. The results of this study could provide a theoretical basis for evaluating the effects of vegetation restoration on ecological hydrological process on the Loess Plateau.