# Influence of Vegetation Filter Strip on Slope Runoff, Sediment Yield and Nutrient Loss
## 5 Conclusions  
The soil and water conservation effects of the two different vegetation setting modes (one block setting and two blocks setting) under the same width were studied by using simulated rainfall with different slope gradients, rainfall intensities in typical eroded gully area of Xuanhua district, Zhangjiakou City, Hebei Province, North China. The following conclusions were drawn:  
1. For the slope area of eroded gully with severe soil erosion and loss, under the condition of certain width of vegetation filter strip, setting vegetation filter strip can effectively reduce soil erosion and nutrient loss on slope surface. However, the effect of the two setting modes of VFS was affected by rainfall intensity and slope gradient, and the best choice can be made under known meteorological and topographic conditions. 2. During the whole rainfall process, within the same time interval after the stable runoff yield, there were also great differences in runoff yield, sediment quantity and nutrient content, and the change of each index over time was not completely stable. This may be related to the change of slope topography during rainfall. However, it was possible to find the same variation trend of the same index in different combinations of rainfall intensity, slope gradient and vegetation coverage. 3. Multiple regression analysis was used to describe the correlation between vegetation, rainfall intensity and slope and erosion indexes. The three factors had significant effects on runoff sediment yield, TP loss in runoff and TN loss in sediment. There was no significant difference in the amount of runoff and sediment yield between the two vegetation setting modes. The TN loss in sediment on the bare land was mainly affected by the rainfall intensity, while the vegetation covered slope was affected by the slope gradient obviously. When the slope was covered with vegetation, rainfall intensity and slope had no significant effect on the content of TP loss in sediment. 4. Based on the heterogeneity analysis of data mining method, this study believed that the effects of rainfall intensity, slope gradient and vegetation setting mode on soil and water loss on slope can be equal or offset. In general, setting vegetation can offset the effect of rainfall intensity and slope gradient, but the effect of vegetation was not obvious under extreme conditions (heavy rainfall and steep slope), and it was also not obvious under light rainfall intensity, which may be due to the small amount of sediment yield, leading to little difference in various indicators. In some cases, the combined action of VFS and slope can offset the influence of rainfall intensity on soil erosion. In general, the influence of rainfall intensity was dominant in most cases. * This research mainly analyzed the correlation between rainfall intensity, slope and vegetation and erosion through multiple regression, and used cluster analysis to study the offsetting effect among the factors affecting erosion. However, the analysis in this research was limited by the experiment performed under restricted conditions. Future experiments may be carried out using other dominant plant species such as _Salsola_ found in the study area, and investigation can be made to further explore the mutual influence or offset effect among the different factors on erosion control in subsequent studies. It is concluded that installing vegetative filter strips on the slope surface can effectively control the soil and water loss in eroded gully, and the effects of various factors on erosion can be equal or offset. The results may provide interesting reference for the practical application of vegetation filter strips, which is beneficial to the implementation of ecological engineering measures. Conceptualization, H.Z. and T.H. ; methodology, H.Z. and T.H. ; software, Q.M. and Q.Y. ; writing--original draft preparation, Q.M. and Q.Y. ; writing--review and editing, X.Z. ; supervision, H.Z. and T.H. ; funding acquisition, H.Z.