茵陈蒿群落垂直结构对坡面产流产沙过程的影响

为探究茵陈蒿群落不同垂直结构对产流、产沙过程的影响,利用人工模拟降雨试验的方法,研究了不同垂直结构的茵陈蒿群落坡面侵蚀过程。结果表明:在植被盖度相同条件下,茵陈蒿多层群落结构(茵陈蒿+狗尾草+生物结皮)和双层群落结构(茵陈蒿+生物结皮)的减流、减沙效果显著优于单层群落结构,二者的减流效益分别为40.5%和22.6%,减沙效益分别为86.6%和73.5%。不同垂直结构的茵陈蒿群落累积产沙量均可表示为累积产流量的幂函数(R~20.98),表现为累积产沙量随累积产流量的增加而增加,且随群落结构层数的增加,3种垂直结构群落的累积产沙量增幅减小。植物根系可以改善土壤结构,增加降水入渗,减少地表径流,是影响产流、产沙过程的关键因素。因此,群落垂直层次多、组分复杂、整体预防水土流失的能力也相应较强。对易于形成植被空层的草地群落,应当重视其低层植被建设,加强草地群落垂直结构及其水土保持功能的相关研究,以期为黄土高原草地植被恢复和结构配置优化提供理论依据。

Effects of Artemisia capillaries Vertical Structures on the Processes of Runoff and Sediment Production

By simulated rainfall experiments,we identified the effects of different vertical structures on runoff and sediment production processes in the community of Artemisia capillaries.The results showed that the reduction effects of runoff and sediment yield of the multi-layer vertical structure (Artemisia capillaries + Setaria viridis (L.) Beauv + biological crusts) and double-layer vertical structure (Artemisia capillaries + biological crusts) were significantly greater than those of the single-layer vertical structure (Artemisia capillaries) under the same condition of vegetation coverage.Compared with the single-layer vertical structure,the other two structures could reduce soil erosion significantly.In addition,runoff was reduced by 22.6％ and 40.5％ over the double-layer vertical structure and multi-layer vertical structure,respectively,and sediment yield was reduced by 73.5％ and 86.6％,respectively.The cumulative sediment yield could be expressed as a power function of the cumulative production flow (R2 ＞0.98),showing that the cumulative sediment yield increased with the augment of the runoff production,and the degree of the enhancement decreased when the community structure became more complex.The results also showed that plant roots could improve soil structure by increasing rainfall infiltration and reducing overland runoff,which was the key factor influencing the runoff and sediment yield processes.All results indicated that the ability of community to prevent soil erosion could be improved with complicated vertical structure and components.In conclusion,in order to provide the theory basis for grassland vegetation restoration and structural configuration optimization for the Loess Plateau,we have to study further the vertical structure of grassland community and reveal the mechanisms of soil and water conservation.