干旱区高寒湿地逆行演替下土壤微生物群落结构的研究

The soil microbial community structure under retrogressive succession of an alpine wetland in the arid area

摘要:

【目的】探究高寒湿地逆行演替对土壤性质与微生物群落结构的影响。【方法】以新疆巴音布鲁克天鹅湖高寒湿地为研究对象，依托逆行演替典型样带(沼泽-沼泽化草甸-草甸)，利用高通量测序技术分析各演替区土壤微生物群落结构。【结果】高寒湿地逆行演替改变了土壤微生物在分类操作单元(operational taxonomic unit, OTU)水平上的物种组成，致使草甸区的微生物ACE、Chao1、Simpson、Shannon多样性指数显著低于沼泽区和沼泽化草甸区(P<0.05)；随着演替发生，变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、拟杆菌门(Bacteroidetes)、子囊菌门(Ascomycota)的相对丰度均减少，放线菌门(Actinobacteria)、芽单胞菌门(Gemmatimonadetes)、担子菌门(Basidiomycota)、被孢霉门(Mortierellomycota)的相对丰度增加；主坐标法分析(principal coordinates analysis, PCoA)排序分析显示，土壤微生物群落在各逆行演替都出现不同程度的离散趋势，其中草甸区中物种离散较大，而沼泽化草甸和沼泽区却都表现出一定的聚集性；进一步的冗余分析(redundancy analysis, RDA)表明，在土壤微生物门和属水平上，土壤有机碳、土壤含水量、土壤容重和微生物量氮、微生物量碳是影响微生物优势菌门的关键因子。【结论】高寒湿地逆行演替导致土壤微生物群落多样性降低，使群落结构由富营养型菌群向寡营养型菌群演变。

Abstract:

[Objective] To explore the effects of retrogressive succession of the alpine wetland of Bayanbulak Swan Lake in Xinjiang on soil properties and microbial community structure by relying on the typical transect of retrogressive succession (swamp-swamped meadow-meadow). [Methods] The soil microbial community structure was analyzed by high-throughput sequencing. [Results] The retrogressive succession of the alpine wetland changed the species composition of soil microorganisms at the operational taxonomic unit (OTU) level. The ACE, Chao1, Simpson, and Shannon diversity indexes of soil microorganisms in the meadow area were lower than those in the swamp area and the swamped meadow area (P<0.05). With the occurrence of succession, the relative abundance of Proteobacteria, Acidobacteria, Bacteroidetes, and Ascomycota decreased, while that of Actinobacteria, Gemmatimonadetes, Basidiomycota, and Mortierellomycota increased. Principal coordinates analysis showed that soil microbial communities presented different degrees of dispersion at each stage of retrogressive succession. The species dispersion in the meadow area was larger than that in the swamped meadow and swamp areas where a certain degree of aggregation appeared. Further, the redundancy analysis indicated that soil organic carbon, soil water content, soil bulk density, microbial biomass nitrogen, and microbial biomass carbon were the key factors affecting the dominant microbial phyla and genera. [Conclusion] The retrogressive succession of the alpine wetland decreased the soil microbial community diversity and led to the transition from eutrophic to oligotrophic community.