文峪河上游河岸带不同植被类型土壤nirS反硝化菌群结构及功能

以文峪河上游河岸带不同演替阶段的8种植被类型五花草甸(WH)、沙棘林(HR)、柳树林(SS)、山杨林(PC)、山杨白桦林(PQ)、山杨白桦落叶松林(PQL)、落叶松云杉林(LP)和云杉林(PM)土壤为研究对象,采用高通量测序技术测定nirS反硝化细菌群落组成及相对丰度,乙炔抑制法测定反硝化酶活性(DEA)。对其土壤理化性质及反硝化细菌群落组成及相对丰度进行方差分析,采用冗余分析(RDA)和Spearman相关性分析不同植被类型及土层反硝化细菌群落结构及功能及土壤理化因子的关联性。结果表明:1)不同植被类型及土层土壤理化因子存在显著差异,柳树林(SS)0—15 cm土层硝态氮(NO~+_3-N)含量显著高于其他植被类型各土层;2)土壤反硝化菌群多样性指数在五花草甸(WH)、山杨白桦林(PQ)和云杉林(PM)中较其他植被类型高;3)沙棘林(HR)及柳树林(SS)反硝化酶活性(DEA)显著高于其他植被类型;4)不同植被类型反硝化优势菌群分布存在显著差异及特异性,如浮霉菌门(Planctomycetes)仅在落叶松云杉混交林(LP)和云杉林(PM)植被类型15—30 cm土层中分布;5)土壤pH、土壤有机碳(SOC)、土壤铵态氮(NH~+_4-N)和硝态氮(NO~+_3-N)等是影响土壤反硝化细菌群落结构及组成的重要因子,其中土壤铵态氮和硝态氮含量变化是导致土壤反硝化菌群多样性和反硝化酶活性差异的关键因子。本研究揭示了文峪河上游河岸带不同植被类型土壤反硝化细菌群落结构及功能的变化和分布特征,为进一步研究该区域河岸带氮素循环及水体污染防治提供重要参考依据。

nirS-type denitrifiers community composition and function in different riparian vegetation types in upper Wenyuhe watershed

In this study, 8 vegetation types, including Multi-flower meadow (WH), Hippophae shrub (HR), Salix shrub (SS), Poplar forest (PC), Poplar birch forest (PQ), Poplar birch and larix forest (PQL), Larix and picea forest (LP) and Picea forest (PM), were selected from different succession stages in the upper Wenyuhe watershed. We aim to determine soil denitrifying bacterial community composition and abundance by using Illumina Miseq high-throughput sequencing method. Meanwhile, acetylene inhibition method was adopted to evaluate soil denitrifying enzyme activities (DEA). The ANOVA analysis on denitrifiers community composition and abundance was carried out consequentially. The correlation coefficient of soil properties and denitrifiers community composition and function were derived through both redundancy analysis (RDA) and spearman correlation analysis. The results showed that 1) nirS-type denitrifiers community composition and function significantly differed in different vegetations types and soil layers. Nitrate contents (NO₃⁺-N) in SS 0-15 cm soil layer were significantly higher than those in other vegetation types. 2) nirS-type denitrifiers diversity index of the WH, PQ and PM were significantly higher than that of other vegetation types. 3) Denitrifying enzyme acitivity (DEA) in HR and SS were significantly higher than that in other vegetation types. 4) Soil denitrifying bacterial diversity and dominant taxa were unique distribution in different vegetations types, such as Planctomycetes was uniquely distribution in 15-30 cm soil layer of LP and PM vegetations. 5) Soil pH, soil organic carbon, ammonium and nitrate nitrogen contents were all important factors influencing soil denitrifiers community structure and composition. Particularly, changes of soil ammonium and nitrate nitrogen were two key factors that could seriously contributed to the variation of soil denitrifying bacterial diversity and enzyme activity. We revealed that characteristics of soil denitrifying bacterial community structure and function among different vegetation types in riparian zone of upper Wenyuhe watershed. It will provide important references for further study of nitrogen cycle and water pollution prevention and control on riparian zones in this region.