不同林龄木麻黄林地土壤细菌及与土壤因子的相关性分析

Correlative Analysis of Soil Factors and Soil Bacteria in Casuarina equisetifolia Woodlands at Different Stand Ages

通过454 GS FLX Titanium测序平台对不同林龄木麻黄林地土壤宏基因组DNA进行16S rDNA定向测序,以分析土壤细菌在不同分类水平上的群落结构多样性的变化并探索土壤理化性质和土壤细菌群落多样性之间的相关性。结果表明,林龄会引起土壤样品中细菌群落的分布显著差异化,木麻黄林地间各菌群的结构变化,门、纲、目、科、属5个分类水平数量和种类的丰度随林龄增加均呈现出先增后降的趋势,其中变形菌门、厚壁菌门、拟杆菌门升降幅度最大,处于中龄林时期的林地土壤微生物相对较丰富,丰度较高的37个属中主要以固氮菌类和生物降解菌类为主。相关性分析表明土壤有机质含量与土壤微生物在门、纲、目、科、属5个分类水平上的多样性均呈现极显著正相关。木麻黄林在由中龄林向成熟林过渡过程中,林地微生物群落结构的变化与林地有机质含量、土壤全钾、全氮、铵态氮、硝态氮等非生物因子的作用有着密切的关系。

In this research 16 S rDNA sequencing of soil macro genomic DNA in Casuarina equisetifolia woodlands at different stand ages was studied by 454 GS FLX Titanium sequencing pyrosequencing technology, to analyze on the changing of the community structure diversity of soil bacteria at different classification levels and its relationships between soil physical-chemical factors and soil bacterial community diversity. The results of diversity analysis showed that stand agescausedthe significant difference in distributionofsoil bacteria, and also the changesin bacteriastructure of Casuarina equisetifolia woodlands. In addition, at different taxonomic levels（from phylum to genus）, the abundance and species of the bacteria in the samples had a tendency to decrease at first and increase later with the stand age growth. The significant change happened obviously in Bacteroidetes,Proteobacteria and Firmicutes. The soil microbes in the woodland at the middle age of forest period were relatively abundant mainly in nitrogen-fixing bacteria and degrading bacteria. The correlation analysis showed that soil organic matter was significantly positively correlated with the microbial diversity at the levels of phylums, classes,orders, family and genus. Microbial community structure changed to some extent from middle-aged forest to mature-aged forest, which was closely correlated with abiotic factors such as soil organic matter, total K, total N,ammonium nitrogen and nitrate nitrogen, etc.