不同盖度羊草地对水土流失的影响

Effects of Leymus Chinensis Grassland Coverage on Soil and Water Loss

[目的]研究羊草盖度与产流产沙量和风蚀量关系,为羊草种植区水土流失防治提供依据。[方法]通过人工模拟降雨试验和风洞模拟试验,研究5种盖度下羊草地的产沙产流特性和抗风蚀特性,对不同盖度羊草地的水土保持效应进行探讨。[结果]坡度相同时,随羊草盖度的增加产流时间逐渐延后;随着盖度的增加,累积径流量的减少率小于累积产沙量的减少率。当羊草盖度由20%增加到100%时,风蚀量减少96.78%;当羊草盖度从60%增加到80%时,风蚀量的减少率明显大于其他相邻盖度风蚀量的减少率。0~23cm高度内收集到的风蚀物占整体风蚀量的70%以上。[结论]羊草地的产流和产沙特征与盖度有密切关系,随着羊草盖度的逐渐增加,产流量和产沙量逐渐减小;羊草地的风蚀速率与盖度呈负相关关系,与风速呈正相关关系。

[Objectives]The relation between community coverage of Leymus chinensis and yields of runoff and sediment were explored to provide references for the control of soil and water loss in those grassland which is dominated by Leymus chinensis.[Methods]Experiments using artificial rainfall and wind tunnel were conducted to study the yield of runoff and sediment and the resistance to wind erosion of five cover scales of Leymus chinensis grassland.[Results]At certain slope degree,the runoff-yielding time was delayed when the cover scale gradually increased.The accumulated decreasing rate of runoff yield loss was less than the corresponding one of sediment yield loss.When Leymus chinensis community coverage increased from20%to 100%,the wind erosion amount decreased by 96.78%;When Leymus chinensis community coverage increased from 60%to 80%,the relative decreasing amount of wind erosion loss was the largest in comparison with the ones of other adjacent communities.The wind erosion amount collected by the sand sampler in 0~23cm height account for more than 70% of the total amount of wind erosion.[Conclusion]The runoff and sediment yields of Leymus chinensis land were correlated closely with cover.I.e.,with the increase of cover,the accumulated runoff and sediment yield showed a trend of declining.It showed a negative correlationbetween the amount of wind erosion and Leymus chinensis cover scale and a positive correlation between the amount of wind erosion and wind speed.