陇中干旱区盐碱土壤剖面微生物群落分布特征

Vertical distribution of microbial communities in saline-alkali soil of the arid area of middle Gansu

以陇中地区典型结皮盐土(HY)、荒漠盐土(XQ)、绿洲农田土壤(YC)为研究对象,分析了土壤垂直剖面(表土层A (0-20cm),心土层B (20-40cm),底土层E (40-80cm))中可溶性盐离子含量、细菌和真菌多样性与群落结构的分布特征,探讨了水盐变化与微生物群落分布的关系。结果表明:土壤盐分呈表层积聚特征,总盐度>6.0g·kg^(-1),属于重度硫酸盐型盐碱土壤,盐碱化程度为HY> YC> XQ。16S rDNA、ITS扩增子高通量测序结果表明盐碱土壤及剖面中放线菌门、变形菌门、绿弯菌门、厚壁菌门为细菌优势群落;子囊菌门、担子菌门为真菌优势群落。沿土壤剖面,细菌多样性呈直线递减、“U”型和单峰模式分布,真菌多样性呈直线下降,较细菌下降更为明显。群落分布特征与长期水盐运移过程形成的土壤剖面异质性相关,其中含水量是剖面微生物群落分布的决定性生态因子,与总盐度、pH共同塑造了特定的群落结构。研究结果阐明了黄土盐碱化过程中微生物群落剖面变化特征,对干旱区黄土的可持续利用及生态修复具有实际指导意义。

The typical crust saline soil(HY),desert saline soil(XQ),and oasis farmland saline alkali soil(YC)were sampled from the arid area of middle Gansu to analyze soluble salt ion content,bacterial and fungal diversity,and community structure along vertical profile[top soil A(0-20cm),core soil B(20-40cm)and bottom soil horizon E(40-80cm)].This work is conducted to explore the relationship between distribution of microbial community and water and salt contents along vertical depth.The results indicate that the sampled soils belong to severe sulfate type saline alkali soil,salt ion are richer in A horizon,and the degree of salinization is ranked as HY>YC>XQ.The results of 16S rDNA and ITS amplicon high-throughput sequencing indicate that the Actinobacteriota,Proteobacteria,Chloroflexi,Firmicutes,Ascomycota,Basidiomycota are all dominated in throughout profiles.The bacterial diversity appears linear descent,"U"and unimodal patterns along depths.Fungal diversity presents as linear descent,and shows a more significant decrease than bacteria.Distribution of microbial community are associated with soil heterogeneity in profile after long-term water-salt transport.Among them,soil moisture content is a determining factor,which shaped microbial community structure jointly with total salt and pH.These results contribute to understanding the mechanisms of microbial community for soil salinization,and have practical guiding significance for the sustainable utilization and ecologically restoration for saline alkali soil in this region.