Capability of soil erosion resistance and evaluation on it for typical forests in Three Gorges Reservoir area

The typical forest types(mixed conifer and broadleaf forest,evergreen broadleaved forest,Phyllostachys pubescens forest,shrub forest,arable land as control) were taken as objects to study the capability of soil erosion resistance of the forest from three aspects of anti-erodibility,anti-scour capability and shear-resistance ability.The judgement matrix was employed to get weight value,and integrative grades were used to give evaluation.Results showed that the aggregation degree was the optimal index for soil anti-erodibility.For the aggregation degree value,the optimum value was in the shrub forest land(37.2%) and arable land(42.4%),the worst value occurred in P.pubescens forest with 10.6%,and the mixed conifer and broadleaf forest(26.2%) performed better than evergreen broadleaved forest(19.4%).In A horizon,where the water erosion events easily happen,the soil of evergreen broadleaved forest had the best soil anti-scour capability with anti-scour coefficient 6.933 L·min /g,followed by shrub forest(4.205 L·min /g),mixed forest(3.783 L·min /g) and arable land(3.046 L·min /g),and the P.pubescens forest soil was the worst(0.789 L·min /g).For the shear-resistance ability,the maximum internal friction angle and cohesion were in the P.pubescens forest and shrub forest respectively.The most possible shear-destroying face will occur in AB and B horizons for mixed forest,B horizon for broadleaved forest,C horizon for P.pubescens forest,AB horizon for shrub forest and B and C horizons for arable land.The results of comprehensive evaluation showed that the shrub forest had the best soil erosion resistance(score 1.50),followed by evergreen broadleaved forest(1.43),and the P.pubescence forest was the worst(0.69).