干旱区沙漠化土地逆转植被的防风固沙效益研究

 使用便携式防沙风速廓线测量仪和阶梯式集沙仪测定了单个植物的阻风作用以及不同恢复阶段植被内的近地面风速、输沙量；同时调查了不同恢复阶段植被的组成、覆盖度,土壤理化性质。结果表明,油蒿、沙蒿、柠条和花棒的个体空间构型分别是:沙蒿、花棒株型为疏散丛生型;柠条株型为中间丛生型;油蒿株型为紧密丛生型;近地面0~50 cm层的阻风阻沙作用效果由强到弱依次为油蒿>沙蒿>柠条>花棒。演替更新过程中,柠条、花棒、沙蒿逐渐衰退,到顶级群落阶段已完全从群落中退出,油蒿形成单一优势种顶级群落。由于优势种群的变化,从初始阶段→发展阶段→相对稳定阶段（顶级群落阶段）的演替更新过程中,近地面粗糙度从0.003 cm、6.039 cm增加到17.726 cm；在流动沙丘2 m高度风速为6.5 m·s-1时,相对稳定阶段没有出现风蚀,发展阶段输沙量只达到1.83 g·cm-1·h-1,占到初始阶段的3.2%。在3 m高度风速相同时,发展阶段近地面风速较初始阶段降低了54.29%,沙结皮厚度达到1~3 mm,所占面积比例达到91%,已经基本实现防风固沙;相对稳定阶段近地面风速较初始阶段降低了83.68%,沙结皮厚度达到5~6 mm,所占面积比例达到98%,完全实现防风固沙。

Effect of Wind-breaking and Sand-fixing of Vegetation in Progressive Succession on Desertification Land in Arid Area

With wind profiler and sand sampler we have measured the wind-breaking effect of single plant,wind velocity and sand flux near ground at different succession stages of vegetation.At the same time we have investigated into the plant community and coverage,and the physo-chemical characteristics of soil.The configuration of Hedysarum scoparium and Artermisia sphaerocephala are nondense tuft,the Caragana korshinskii configuration is mid-dense tuft,and the A.ordosica configuration is dense tuft.The wind-breaking and sand-preventing effect in 0~50 cm near ground layer is A.ordosica > Artermisia sphaerocephala > Caragana korshinskii > Hedysarum scoparium. In the processes of progressive succession,Hedysarum scoparium,Caragana korshinskii,and Artermisia sphaerocephala decayed gradually,even disappeared at the stage of climax community;whereas,Artermisia ordosica continuously increased and finally formed the single predominant community.From the initial stage(mobile sands) to the developing stage and to the relatively stable stage,the roughness length of near ground changed form 0.003 cm to 6.039 cm and to 17.726 cm due to changes of predominant community.When the wind velocity at height of 2 m on the mobile sand dunes reached 6.5 m\5s~(-1),there was no wind erosion at dune relatively stable stage,and the sand flux at dune developing stage was only 1.83 g\5cm~(-1)\5h~(-1),occupying 3.2% of the moving dunes.When the wind velocity at height of 3 m was the same,the wind velocity near ground of the developing stage was reduced by 54.29% compared with that of the initial stage;the thickness of sand crust accumulated up to 1~3 mm,making up 91% of the total area,which can basically play a role of desert control.The wind velocity near ground of the relatively stable stage was reduced by 83.68% compared with that of the initial stage;the thickness of sand crust accumulated up to 5~6 mm,making up 98% of the total area,which can effectively play a role of desert control.