古尔班通古特沙漠南缘梭梭固沙林土壤粒度的分异规律

目的]分析梭梭林地的防风固沙效果,为当地的沙漠化防治提供基本的资料,为生态建设提供可靠的依据。方法]以古尔班通古特沙漠南缘莫索湾地区的梭梭(Haloxylon ammodendron)林地为研究区,按照距离沙源远近,分别选取了4种典型的梭梭样地,进行土壤样品采集,分析其粒径分布特征。结果]位于沙源处的梭梭林由于沙尘来自古尔班通古特沙漠,沙源均一性以及分选性良好。土壤粒径主要受植被盖度的影响,使得沙地表层细粒成分增加;在一定的植被覆盖下,随着沙源距离的增大,表层土壤平均粒径依次减小,主要是因为植被拦截沙尘物质,使得表层土壤粒径产生差异;表层土壤平均粒径相对于下层呈增大趋势,且距离沙源越近变化幅度越大,但是土壤粒径峰度、偏度差异不大。结论]表层土壤粒度特征存在差异反映了各梭梭林在不同的植被覆盖下风沙活动强度对其的影响,自然植被带与人工梭梭林能够有效拦截和固定大量的风蚀物质,但由于自然植被生长状况不如人工林,在植被大量衰退和强风蚀作用下对风沙的拦截作用较弱,因此,在自然植被带外围人工造林对当地风沙的阻挡作用起到至关重要的作用。

Soil Particle Size Differentiation of Haloxylon Ammodendron Sand-Break Forest in Southern Margin of Gurbantunggut Desert

Objective] The windbreak and sand fixation effects of Haloxylon ammodendron forest lands were analyzed to provide insights for local desertification control and reliable basis for ecological construction.Methods] H. ammodendron woodland in the Mosuowan area on the southern edge of the Gurbantunggut Desert was taken as a study area. According to the distance from the sand source, four typical H. ammodendron sample plots were selected for soil collection, and the particle size distribution characteristics were analyzed.Results] H. ammodendron forest located at the sand source had good uniformity and sorting of the sand source because of the dust coming from the Gurbantunggut Desert. The soil particle size was mainly affected by vegetation coverage, which increased the fine-particle composition on the sand surface. Under certain vegetation cover, the average grain size of the surface soil decreased with the increase of sand source distance, mainly because vegetation intercepts sand and dust substances, causing a difference in the particle size of the surface soil. The average particle size of the surface soil increased compared with the lower layer, and there was greater variation close to the sand source. However, the difference in kurtosis and skewness of soil particle size was not significant.Conclusion] The difference in particle size characteristics of the surface soil reflected the influence of wind-sand activity intensity on H. ammodendron forests under different vegetation coverage. Natural vegetation zones and artificial H. ammodendron forests could effectively intercept and fix a large amount of wind erosion substances. However, because the growth condition of natural vegetation was not as good as that of artificial forest, the effect of the interception of wind-blown sand was weaker under vegetation degradation and wind erosion. Therefore, afforestation on the periphery of the natural vegetation zone played a vital role in blocking local wind-blown sand.