不同根系构型草本与灌木复合对土壤饱和导水率的影响因素分析及模拟

Analysis and Simulation of Factors Affecting Soil Saturated Hydraulic Conductivity by Combinations of Grasses and Shrubs with Different Root Configurations

[目的]探究不同根系构型草本与灌木复合时的根土性质的差异对土壤饱和导水率的影响,并综合考虑根系和土壤性质建立估算土壤饱和导水率的经验方程,为黄土高原植被恢复后的水文模型建立提供理论参考。[方法]选取不同根系构型草本与灌木的混合样地,分别为柠条锦鸡儿加冰草(须根系)和柠条锦鸡儿加铁杆蒿(直根系)。采用双环刀法测定不同样地土壤饱和导水率。[结果]样地类型和土层深度对土壤饱和导水率的影响达到显著水平,两者对土壤饱和导水率影响的因子贡献率分别为26%和52%。直根系铁杆蒿与柠条锦鸡儿混合样地的土壤饱和导水率高于须根系冰草与柠条锦鸡儿混合样地,并且不同样地的土壤饱和导水率随土层深度的增加均表现出降低的趋势。根长密度、团聚体以及土壤容重能够较好地模拟土壤饱和导水率,其拟合精度R 2可以达到0.86。[结论]直根系草本与灌木复合时较须根系草本与灌木复合相比具有更高的饱和导水率。在不同样地中,根长密度、团聚体以及土壤容重是影响饱和导水率的主要因素。

[Objective]The impacts on soil saturated hydraulic conductivity that occur because of differences in root and soil properties between combinations of grasses and shrubs having different root configurations were studied,and an empirical equation for estimating soil saturated hydraulic conductivity was established by comprehensively considering root and soil properties in order to provide a theoretical reference for the establishment of hydrological models appropriate for conditions following vegetation restoration on the Loess Plateau.[Methods]Plots of grass-shrub mixtures having different root system configurations were used:Agropyron cristatum and Caragana korshinskii,and Artemisia gmelinii and Caragana korshinskii.Saturated hydraulic conductivity was measured by the double-ring knife method.[Results]The influence of sample grass-shrub mixture type and soil depth on soil saturated hydraulic conductivity was significant,and their factor contribution rates on soil saturated hydraulic conductivity were 26%and 52%,respectively.The soil saturated hydraulic conductivity of the tap-root grass Artemisia gmelinii and Caragana korshinskii mixture was greater than that of the fibrous root grass Agropyron cristatum and Caragana korshinskii mixture.Soil saturated hydraulic conductivity of different plots declined with increasing soil depth.Root length density,soil aggregates,and soil bulk density better simulated soil saturated hydraulic conductivity,with a fitting accuracy(R 2)reaching 0.86.[Conclusion]The combination of a taproot grass and a shrub had a higher saturated hydraulic conductivity than observed for the combination of fibrous root grasses and shrubs.Root length density,soil aggregates,and soil bulk density were the main factors affecting saturated hydraulic conductivity.