[Effects of different vegetation protection measures on erosion prevention of unpaved roadside slopes in Three Gorges Reservoir Area].

One of the main impacts of road construction is the creation of bare and steep slopes when lack of vegetation protection, which usually generates serious soil loss, a major erosion source in mountainous areas. In this study, six treatments including planting grass (GRA), grass and bush (GBC), building terrace combined with grass and bush (TGB), planting sod strip (SS), building sloping farmland (SFL), and building sloping farmland combined with grass (SFLG) were installed on the newly constructed unpaved roadside slopes in Three Gorges Reservoir Area to investigate the effects of these measures on the erosion prevention of the unpaved roadside slopes under natural rainfall. Among the six treatments, GBC had the best effect, which had the quickest revegetation rate (the mean vegetation coverage increased from 20.2% to 91.6%), decreased the soil bulk density by 9.5%, and increased the saturated hydraulic conductivity by 678.1%, followed by GRA and SS. TGB had the greatest potential in mitigating soil loss and runoff, with the efficiency in trapping sediment and runoff reached 80.2% and 72.3%, respectively, being appropriate for the cut slopes with a gradient greater than 45 degrees, followed by GBC and GRA. GRA had a higher efficiency on fill slope than on cut slope, while GBC showed greater applicability on cut slope. On the fill slope with a moderate gradient 15 degrees, SFLG had a potential of trapping 23.0% of sediment, which was equivalent to that of GRA and GBC, but the efficiency in trapping runoff was only 2.0%. When the fill slopes with a gradient less than 15 degrees were utilized as farmland, a grass buffer strip of 2 m length was needed on the upslope for erosion control.