陕北不同地貌部位土壤抗冲性特征研究

以陕北吴起县为例,采用原状土冲刷法,对各地貌部位不同植被类型问的土壤抗冲过程进行测试研究,结果表明:(1)在抗冲过程初期土壤抗冲值均较小,且随时间逐渐增大,随后抗冲值随时间呈波浪式变化,呈现单峰、双峰和多峰变化,除农地外所有土样在整个抗冲过程均有突变值的存在;(2)在梁(峁)顶、梁(峁)坡、沟坡和沟底,抗冲性最强的植被类型分别为沙棘林(草地)、油松小叶杨山杏混交林、柠条林和旱柳小叶杨混交林,农地的抗冲性能最差;(3)草地和灌木林在各地貌部位问的抗冲刷系数都表现为:梁峁顶>梁峁坡>沟坡>沟底,乔木林总体上表现为:梁峁坡>梁峁顶>沟坡>沟底,林分类型间的抗冲性表现为:针阔混交林>阔叶混交林>针叶纯林>阔叶纯林;(4)不同整地方法下的土壤抗冲性也表现出很大的差异,以油松林为例,表现出水平阶整地的抗冲性能优于鱼鳞坑,另外水平阶阶坎上的土壤抗冲刷系数要高于水平阶阶面,其他整地方法的抗冲性能有待进一步研究.

Study on Soil Anti-scourability of Different Topography Positions in Northern Shaanxi

Take Wuqi county in northern Shaanxi as example,by Scour method of undisturbed soil,soil antiscour process of the different vegetation types in each topography position were tested and studied.Results showed that:(1)Soil anti-scour values were all small and increased gradually in the initial stage of anti-scour process,subsequently,followed by change of wave form with unimodal,bimodal and multi-peak.With the exception of farmland,there were break points in all soil samples in the process of soil anti-scour.(2)Buckthorn shrub(grassland),mixed forest of Chinese Pine-Simon Poplar-Prunus Armeniaca,Caragana shrub and mixed forest of Willow-Simon Poplar were strongest in ability of anti-scour respectively in top vally,vally slope,gully slope,gully bottom,Farmland were worst in ability of anti-scour.(3)Soil anti-scour coefficdent of grassland and shrab in each topography position were as follows:top vally>ally slope>gully slope>gully bottom.The arbor forest were as follows:ally slope>top vally>gully slope>gully bottom.Soil anti-scour ability among stand types presented as:mixed wood>broadleaved mixed forest>pure broadleaved forest>pure needles forest.(4)Soil anti-scourability trader different methods of land preparation appeared different.Take Chinese Pine forest as an example.anti-scourability in level-terrace site preparation were better than in scale ripple site preparation,while soil anti-erosion coefficient on level-terrace platform is higher than on level-terrace step.Soil anti-scourability shoud be studied further in other methods of land preparation.