甘肃小陇山油松与柴胡栽培土壤细菌群落特征

Soil bacterial communities under Pinus tabulaeformis Carr. and Bupleurum chinense plantations at Xiaolongshan Mountain of Gansu Province

土壤细菌能够有效促进土壤中物质循环和能量流动,其群落组成、数量及多样性能够反映土壤质量状况。研究不同植被对土壤细菌群落结构和多样性的影响,有助于深入了解土壤健康状况,对实现植被管理和土地可持续利用具有重要意义。以甘肃小陇山移栽至耕地(耕地前期种植柴胡)后生长4年的人工油松苗(Pinus tabulaeformis Carr)土地和长期种植柴胡(Bupleurum chinense)土地的表层土壤(0—30 cm)为对象,采用Illumina Miseq高通量测序技术对2种人工植被下土壤细菌群落进行测定,分析了土壤细菌的Alpha多样性、群落组成和丰富度,并研究土壤化学性质对细菌群落结构的影响。结果表明:1)两种不同植被的土壤细菌群落丰度和多样性无明显差异,但油松地土壤细菌群落均匀度明显小于柴胡地土壤。2)所测土壤样品中共检测到细菌的37个门,84个纲,168个目;其中,主要的优势菌门为变形菌门(Proteobacteria),酸杆菌门(Acidobacteria),绿弯菌门(Chloroflexi),浮霉菌门(Planctomycetes),放线菌门(Actinobacteria),且油松地土壤中的变形菌门(Proteobacteria)的丰富度显著低于柴胡地土壤(P <0. 05),绿弯菌门(Chloroflexi)丰富度却显著高于柴胡地(P <0. 05);主要的优势菌纲为酸杆菌纲(Acidobacteria),β-变形菌纲(Betaproteobacteria),放线菌纲(Actinobacteria),变形菌纲(Alphaproteobacteria)和芽单胞菌纲(Gemmatimonadetes),但各优势菌纲的丰度在两个植被土壤之间差异不显著(P>0.05)。3)变形菌门(Proteobacteria)丰富度与土壤的碱解氮含量呈显著负相关(P<0.05),酸杆菌门(Acidobacteria)丰富度与全氮含量显著负相关(P<0.01);通过RDA分析发现,碱解氮和全氮是影响细菌群落结构的最主要因子。可见,油松和柴胡植被土壤细菌群落结构及多样性差异不大,但油松地土壤细菌群落的物种分配较柴胡地集中,且优势细菌门中的变形菌门和绿弯菌门在两者之间的差异显著,同时,碱解氮和全氮含量是影响2种植被土壤细菌群落的主要因子。这些结论为了解小陇山不同植被土壤微生物群落组成及多样性提供理论,也为当地进行人工油松苗的种植、经营及土壤管理提供参考。

Soil bacteria can effectively promote energy flow and material circulation in soil, and the soil quality condition can be reflected by the composition, quantity, and diversity of bacterial communities. This study aimed to investigate the effects of different vegetation types on soil bacterial community structure and diversity, assisting us to completely understand soil quality condition and facilitate effective management and sustainable utilization of vegetation in the Xiaolongshan Mountain region. Soil was collected from Pinus tabulaeformis and Bupleurum chinense plantations at Xiaolongshan Mountain of Gansu Province. High-throughput sequencing technology was used to analyze the community structure and diversity of soil bacteria under the two different types of vegetation, and to analyze the effects of soil nutrient indices on soil bacterial community structure. The results showed that （1） The abundance and diversity of bacterial communities were not different between the two vegetation-type soils; however, the bacterial communities in P. tabulaeformis plantation soil had lower uniform degree than those in the B. chinense soil. （2） The ribosomal database project classifier revealed 37 phyla, 84 classes, and 168 orders of bacteria in the soil samples under the two types of vegetation. The dominant phyla were Proteobacteria, Acidobacteria, Chloroflexi, Planctomycetes, and Actinobacteria; Proteobacteria had lower abundance in the P. tabulaeformis soil than in the B. chinense soil （P 〈 0.05）. Chloroflexi had higher relatively abundance in the P. tabulaeformis soil than in the B. chinense soil （P 〈 0.05）, whereas the relative abundance of other dominant bacteria showed no difference between the two vegetation-type soils. At the class level, Acidobacteria, β-proteobacteria, Actinobacteria, and Gemmatimonadetes were the predominant bacterial communities, and their relative abundance showed no difference between the two vegetation-type soils. （3） The relative abundance of Proteobacteria was significantly negatively correlated with available nitrogen （P 〈 0.05）, and the relative abundance of Acidobacteria was significantly negatively correlated with total nitrogen （P 〈 0.01）. The results of redundancy analysis showed that available nitrogen and total nitrogen had the greatest impact on the soil bacterial community structure. These results suggest that the community composition and diversity of bacteria were similar in the two soils under different vegetations, but the species of bacterial communities in the P. tabulaeformis soil showed more centralized distribution than those in the B. chinense soil. In conclusion, Proteobacteria and Chloroflexi were the dominant phyla and showed significantly different distribution in the two vegetations, and available nitrogen and total nitrogen were the main factors affecting the soil bacterial community structure.