摘要
草地植被能有效控制坡面侵蚀,然而不同草地植被类型及其冠层与根系对坡面侵蚀过程的调控作用尚缺乏系统研究。采用人工模拟降雨方法,定量研究了不同雨强下苜蓿与黑麦草冠层与根系对黄土坡面侵蚀过程、径流侵蚀动力及土壤抗侵蚀能力特征的影响。结果表明:与裸坡相比,苜蓿与黑麦草的平均减流效益分别为17.65%和9.80%,减沙效益分别为63.86%和69.88%。不同雨强下两种草被根系减流减沙的平均相对贡献均高于冠层,且根系减沙的相对贡献随雨强的增加而增大。草地植被主要通过削减坡面径流流速和增加坡面阻力的方式实现对降雨径流侵蚀动力的调控,草被根系对坡面径流的减速作用略大于冠层,但其增阻作用却明显小于冠层。黑麦草对坡面径流的减速增阻效益高于相同部位的苜蓿。坡面土壤侵蚀率与水流切应力的关系可用幂函数y=αx^(β)较好地拟合。幂函数系数α解释为单位水流切应力所引起的土壤侵蚀模数,可作为反映土壤抗侵蚀能力的指标。草被根系作用下的幂函数系数减幅远高于冠层,反映了其增强土壤抗侵蚀能力作用明显高于冠层,这主要源于草被根系结构对表层土壤性质的改善。须根系黑麦草强化土壤抗侵蚀能力优于直根系苜蓿。本研究揭示了草地植被调控坡面侵蚀过程是通过地上冠层与根系的共同作用达到同时调控侵蚀动力和土壤抗侵蚀能力实现的,草被根系对坡面侵蚀控制起主导作用,且以须根系草被对黄土坡面侵蚀的调控效果最佳。上述结果可为草地侵蚀过程研究及黄土高原草被建设与管理提供科学依据。
Grassland vegetation can effectively control slope erosion.However,the regulation effects of different grassland vegetation types and their canopies and roots on slope erosion have not been systematically studied.In this study,artificial simulated rainfall experiments were used to quantitatively study the effects of canopies and roots of alfalfa(Medicago sativa)and ryegrass(Lolium perenne)on soil erosion processes of loess slope,hydrodynamic parameters and soil erosion resistance characteristics under different rainfall intensities.The results showed that the average runoff reduction benefit of alfalfa and ryegrass was 17.65%and 9.8%,and the sediment reduction benefit was 63.86% and 69.88%,respectively,compared to bare slope.The average relative contribution rates of the roots to the benefit of the runoff reduction and sediment reduction were higher than those of the canopies under different rainfall intensities.And the relative contribution rate of the roots to the benefit of the sediment reduction increased with the increase of rainfall intensity.Grassland vegetation regulated erosion dynamics mainly by reducing flow velocity and increasing slope resistance.The effect of the roots in decreasing flow velocity was slightly greater than that of the canopies,but the effect of the roots in increasing slope resistance was obviously smaller than that of the canopies.The effects of ryegrass in decreasing flow velocity and increasing slope resistance were higher than those of the same part of alfalfa.A power function y=αx^(β) fitted better in flow shear stress and slope erosion rate relationship.The coefficientαof the power function can be interpreted as the modulus of soil erosion caused by unit flow shear stress,and can be used as an index to reflect soil erosion resistance.The reduction benefit of the coefficientαunder the action of the roots was much higher than that of the canopies,which reflected that the roots had significantly enhanced soil erosion resistance compared to the canopies.The enhancement of soil erosion resistance was mainly attributed to the improvement of soil properties in the topsoil layer by the roots of grassland vegetation.In this study,bulk density of grassland vegetation plots decreased significantly,and soil organic matter,soil porosity,saturated hydraulic conductivity,mean weight diameter of soil aggregates and shear strength of them increased obviously compared to bare slope plot.The soil properties of the grassland vegetation plots were obviously improved,which consequently enhanced the soil erosion resistance.The roots of grassland vegetation improved the soil properties in the topsoil layer,and its ability to enhance soil erosion resistance was much greater than that of the canopies.Furthermore,the ability of ryegrass with fibrous root system to strengthen soil erosion resistance was better than that of alfalfa with taproot system.The study revealed that grassland vegetation could control slope erosion processes through the joint action of canopies and roots to regulate erosion dynamics and soil erosion resistance,simultaneously.The roots of grassland vegetation played a leading role in controlling slope erosion,and grassland vegetation with fibrous root system had the best effect on the control of loess slope erosion.The results can provide scientific support for the study of soil erosion processes of grassland and the construction and management of grassland on the Loess Plateau.
作者
陈浩
王豆豆
崔钦凯
王博
刘俊娥
李占斌
CHEN Hao;WANG Doudou;CUI Qinkai;WANG Bo;LIU Jun′e;LI Zhanbin(College of Life Science,Yan′an University,Yan′an 716000,China;Institute of Water Resources and Hydro-Electric Engineering,Xi′an University of Technology,Xi′an 710048,China;Shaanxi Engineering and Technological Research Center for Conversation and Utilization of Regional Biological Resources,Yan′an 716000,China;School of Geography and Tourism,Shaanxi Normal University,Xi′an 710119,China)
出处
《生态学报》
CAS
CSCD
北大核心
2024年第15期6841-6853,共13页
Acta Ecologica Sinica
基金
国家自然科学基金项目(42107359)
中国博士后科学基金项目(2022MD713800)
延安市高层次人才专项项目(2019-16)
延安大学科研计划资助项目(YDBK2019-63)。
关键词
土壤侵蚀过程
水动力学参数
土壤抗侵蚀能力
冠层
根系
黄土高原
soil erosion processes
hydrodynamic parameters
soil erosion resistance
canopy layer
root
the Loess Plateau
