Effects Of Artificial Vegetation Types And Different Growth Stages On Hydrological Characteristics In Steep Slopes

The"Grain for Green"measures implemented by the country have effectively controlled soil and water losses in the slope area of the Loess Plateau,but extensively afforestation continuously consumed soil water resources,inevitably affected the water cycle process of the Loess Plateau.Investigating the effects of different vegetation types on hydrological characteristics in slope areas during vegetation restoration is useful to the rational utilization of soil water resources and the continuous optimization of ecological environment in the Loess Plateau.Therefore,in this study,using the steep slope of the Wangdonggou small watershed in the Loess Plateau Gully Area as the research area and natural rainfall conditions,the vegetation growth,soil physical properties,water and soil erosion,canopy interception and soil moisture of grassland,shrub,pure arbor forest and mixed arbor forest at different restoration period were compared and analyzed,and the responses of hydrological characteristics on steep slope to different artificial vegetation types and the changes with vegetation restoration were studied.The following main conclusions were drawn,(1)With the restoration of vegetation,the soil physical and chemical properties of 0-40cm of different vegetation types showed a trend of continuous improvement.In general,the improvement effectivenesses of shrub-arbor mixed,arbor-tree mixed forest on soil organic matter,soil bulk density,porosity,water holding capacity and saturated water conduction rate were better than those of grassland,shrubland and pure arbor forest.(2)During the observation period of the two vegetation growing seasons,the in-forest throughfall of each vegetation type was linearly positively correlated with the secondary rainfall outside the forest(R~2>0.97),the canopy interception rate decreased exponentially with the increase of the secondary rainfall outside the forest(R~2>0.90).The canopy interception effect was significantly different between different vegetation types(P<0.05),the canopy interception effect of Hippophae rhamnoides shrub was the best among the eight vegetation types.In addition,based on the LAI and other parameters,the interception equation in the Hydrus-1D model could be better used to simulate the canopy interception(R~2>0.80)of eight vegetation types in this study during the growth period.(3)With the restoration of vegetation,the amount of surface runoff and sediment in each vegetation type showed a gradually decreasing trend.However,there were differences in the reduction of surface runoff and sediment for different vegetation types,the control effect for surface runoff and soil erosion of grassland,shrubland,mixed forest of arbor and shrubs was better than that of pure arbor forest.(4)There were differences in the average water content of soil profile(0-500 cm)for different vegetation types.Pure shrubland,pure arbors and their mixed forests consumed more soil moisture than grasslands,especially mixed trees consumed the most water.With the restoration of vegetation,the soil profile moisture content of each vegetation type decreased rapidly and then gradually increased,the soil moisture recovery effect of Bothriochloa ischaemum,Robinia pseudoacacia,Robinia pseudoacacia×Hippophae rhamnoides,Robinia pseudoacacia×Platycladus orientalis and Platycladus orientalis was better.