机械沙障固沙对生物土壤结皮形成发育的影响

Effect of sand barrier fixation on the formation and development of biological soil crust

生物土壤结皮对荒漠生态系统维持稳定发挥着重要作用。因此,在干旱沙区利用机械沙障辅助措施促使生物土壤结皮的形成发育具有重要意义。本文利用微生物高通量测序结合土壤理化性质测定研究机械沙障固沙(草方格、网格和覆网)对生物土壤结皮形成发育的影响。结果表明:草方格和网格中结皮颜色与藻结皮相近,覆网中结皮的盖度最高,厚度最厚;3种机械沙障固沙中结皮的黏粒和粉粒比例均显著高于流沙,覆网中结皮的营养化程度最高,也就是成土程度最高;从3种机械沙障固沙中结皮真菌、细菌和蓝藻的组成分析得知,覆网结皮的细菌组成中蓝藻门(Cyanobacteria)和蓝藻组成中瘦鞘丝藻属(Leptolyngbya)的比例比草方格和网格中结皮的高,真菌组成中座囊菌纲(Dothideomycetes)和蓝藻组成中微鞘藻属(Microcoleus)的比例低,而且独有微生物OTU数量最高。依据以往干旱区生物土壤结皮成土过程及微生物演替规律推测,覆网中结皮的发育程度很可能高于草方格和网格,其形成和发育轨迹不同于后两者。因此,3种机械沙障固沙中覆网最有利于生物土壤结皮的形成发育。

The biological soil crust is important for maintaining stability in desert ecosystems.Therefore,the use of sand barriers as auxiliary measures to promote the formation and development of biological soil crust in arid areas is of great significance.In this paper,the effects of sand fixation by sand barriers(straw checkerboard,nylon grids,and covered nets)on the formation and development of biological soil crusts were studied using microbial high-throughput sequencing combined with soil physical and chemical properties determination.The results showed that the crust thickness under the covered nets was the thickest,although the colors of the crust in the straw checkerboard and nylon grids were similar to that of the algae crust.The proportions of clay and powder particles in the crust of the three types of sand barriers for sand fixation were significantly higher than that of the moving sand.The nutrition degree of the crust in the covered nets was the highest,indicating the highest degree of soil formation.From the composition analysis of fungi,bacteria,and blue-green algae in crusts from the three types of sand barrier,it was found that the proportions of Cyanobacteria and Leptolyngbya in the crust in the covered nets were higher than those in the crust in the straw checkerboard and nylon grids.In contrast,the proportions of Dothedeomycotes and Microcolleus were lower,and the number of unique microbial OUT was highest.Based on the previous process of soil crust formation and microbial succession in arid areas,it was inferred that the degree of crust development in the cover nets was likely higher than that in the straw checkerboard and nylon grids and that their formation and development trajectory differ.Therefore,among the three types of sand barriers,the covered nets for sand fixation were more suitable for biological soil crust formation and development.