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    三峡库区典型林分土壤抗侵蚀性能及评价

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

    • 摘要: 以三峡工程库区典型植被类型 (针阔混交林、常绿阔叶林、楠竹林、灌木林、农地对照)为研究对象,从抗蚀性、抗冲性和抗剪性3个角度进行林地土壤抗侵蚀性能研究,并采用判断矩阵获得指标权重,用综合评分法进行评价。结果表明:土壤团聚度为三峡库区林地土壤最佳抗蚀指标;土壤团聚度平均值表现为灌木林(37.2%)和农地(42.4%)最优,楠竹林(10.6%)最差,针阔混交林(26.2%)优于常绿阔叶林(19.4%)。在最易被径流冲刷的土壤A层,抗冲刷系数为:常绿阔叶林(6.933 L·min/g)灌木林(4.205 L·min/g)针阔混交林(3.783 L·min/g)农地(3.046 L·min/g)楠竹林(0.789 L·min/g)。林地土壤抗剪强度指标内摩擦角以楠竹林最大(25.60°),土壤黏聚力值以灌木林最大(16.51 kPa);最易发生剪切破坏的土壤层分别出现在针阔混交林的土壤AB层和B层,常绿阔叶林的土壤B层,楠竹林的土壤C层,灌木林的土壤AB层,农地土壤的B层和C层。综合评价结果为:灌木林土壤抗侵蚀作用最强(得分1.50),其次为常绿阔叶林(1.43),楠竹林最差(0.69)。

       

      Abstract: 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).

       

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