延安麻塔流域植被对土壤侵蚀的控制效率研究

Study on the control efficiency of vegetation on soil erosion in mata watershed of Yanan City

定量刻画植被对土壤侵蚀的控制效率对区域水土保持评估具有重要的意义。目前学者多采用土壤保持量指标来衡量植被对土壤侵蚀控制效率,然而该指标强烈的受到区域潜在土壤侵蚀量影响,从而导致低估或高估植被对土壤侵蚀控制效率。本研究在土壤保持量的基础上,构建了土壤侵蚀控制指数,并将该指数应用于延安麻塔流域的土壤保持功能评估中。结果表明:(1)土壤侵蚀控制指数比土壤保持量在区域土壤保持功能评估中更能有效的在流域尺度上侦测植被对潜在土壤侵蚀控制效率;(2)麻塔流域植被总体上具有较高的土壤侵蚀控制指数(均值为0.92);(3)土壤侵蚀控制指数主要受到植被和坡度单独作用的影响,两者能够解释侵蚀控制指数84.11%的变异来源;(4)由于麻塔流域潜在土壤侵蚀量较大(114100 t·km^-2·a^-1),导致该区仍然具有较高的土壤侵蚀模数(8200 t·km^-2·a^-1),因此采取工程措施治理水土流失必须进一步加强。

Quantitative characterization the control efficiency of regional vegetation structure to potential soil erosion is of great significance for regional assessment of soil and water conservation.At present,most scholars use soil conservation amount(SCA)to measure the control efficiency of vegetation on soil erosion.However,this indicator is strongly affected by potential regional soil erosion,which leads to underestimation or overestimation of the control efficiency of vegetation on soil erosion.Based on the concept of SCA,a soil erosion control index(SECI)was constructed in this study.Then,it was applied to the assessment of soil conservation function in mata watershed ofYanan city.The results show that:(1)SECI is more effective in detecting erosion control efficiencyof vegetation than that of SCA in regional soil conservation assessment at watershed scale,because the SECI is a relative proportion of erosion control and is not affected by the regional differences of potential soil erosion;(2)on the whole,the vegetation in mata watershed has a high soil erosion control index,with an average value of 0.92 in mata watershed;(3)SECI is mainly affected by vegetation and slope,which can explain 84.11%of the variation sources of erosion control index;(4)because of large amount value of potential soil erosion in this area(114100 t·km^-2·a^-1),it still has a higher value of soil erosion modulus(8200 t·km^-2·a^-1)in mata watershed.Therefore,engineering strategies for reducing erosion modulus should to be further strengthened in the region.