黄土高原陡坡地不同植被类型及恢复过程对径流泥沙的影响

Effects of Different Vegetation Types and Restoration Processes on Runoff and Sediment on Steep Slopes of the Loess Plateau

[目的]探究不同植被类型及其恢复过程对陡坡地水土流失的影响差异,寻找可以更好地控制陡坡地水土流失的植被类型,进而为黄土高原流域生态环境治理提供理论指导。[方法]基于黄土高塬沟壑区王东沟流域坡地9种不同植被类型的径流小区14 a(2008—2021年)的降雨、LAI和径流泥沙数据,采用单因素方差分析和线性回归分析的方法,研究了不同植被类型的径流泥沙随植被恢复的变化。[结果]不同植被类型减少径流泥沙效果存在差异,侧柏林多年地表径流和土壤侵蚀模数显著高于其他植被类型(p<0.05),其余8种植被间不存在显著差异(p>0.05),白羊草与沙棘林的平均值较低。随着植被恢复,各植被LAI逐渐提高,地表径流与土壤流失显著降低,但不同植被类型表现出的递减规律具有差异,在2021年,白羊草、沙棘、沙棘×刺槐和刺槐林的地表径流和土壤侵蚀模数低于其他植被类型。各植被类型的地表径流与土壤侵蚀模数均符合线性关系(p<0.01),函数系数代表单位径流导致的土壤流失,反映了植被控制土壤侵蚀的能力,白羊草的效果最佳。[结论]草、灌及其混交林的植被恢复措施较纯乔木林可以更好地控制黄土高原陡坡地的水土流失。

[Objective]The aim of this study is to explore the impacts of different vegetation types and restoration processes on soil and water loss on steep slopes,to find the vegetation types that can better control soil and water loss on steep slopes,and then to provide theoretical guidance.[Methods]Based on the long-term observation data of rainfall,LAI(leaf area index),surface runoff and soil erosion in 9 runoff plots from 2008 to 2021,conducted in the Wangdonggou watershed of the Loess Plateau,the changes of surface runoff and soil erosion with vegetation restoration in different vegetation types were studied using one-way ANOVA method and linear regression method.[Results]There were significant differences in the impacts of different vegetation types on reducing runoff and sediment on steep slopes.The annual average surface runoff and soil erosion modulus under Platycladus orientalis were significantly higher than those of other vegetation types(p<0.05),without significant differences among the other 8 vegetation types(p>0.05).The average annual runoff and erosion modulus under Bothriochloa ischaemum and Hippophae rhamnoides were at a low level.With the restoration of vegetation,the LAI of each vegetation type increased gradually,the surface runoff and soil loss decreased significantly,and the declining trends of different vegetation types were different.Comparatively,the decreasing rates of surface runoff and soil loss under Platycladus orientalis were significantly greater than those under other vegetation types(p<0.05).In 2021,the surface runoff and soil erosion modulus under Bothriochloa ischaemum,Hippophae rhamnoides,Hippophae rhamnoides×Robinia pseudoacacia and Robinia pseudoacacia were lower than those under other vegetation types.The surface runoff and soil erosion modulus of each vegetation type were linearly related(p<0.01),and the coefficient of the linear function represented the soil loss per unit of surface runoff,reflected the ability of vegetation to control soil erosion.[Conclusion]Among the 9 vegetation types,the impact of Bothriochloa ischaemum was the largest.The vegetation restoration measures in grasses,shrubs and mixed forests were better to reduce soil erosion on steep slopes of the Loess Plateau than pure arbor forests.