中文摘要：

酸沉降显著影响着土壤生态系统的结构组成与系统功能，但对我国南方花岗岩发育的酸性土壤细菌群落结构及多样性的影响还知之甚少。因此，本文以酸沉降影响严重的亚热带地区花岗岩发育的剖面（0-100cm）土壤为对象，采用不同酸度的HCl-NH4Cl溶液（pH=3．5，4．5，5．5）对A层（0-12cm）、B层（12-50cm）与C层（50-100cm）土壤分别进行分批次淋溶实验（Batch方法），探讨在此特定实验条件下酸溶液作用前后土壤细菌群落结构及多样性的变异特征。研究结果表明，利用Miseq技术对土壤细菌16S rRNA基因进行高通量测序与分析发现酸溶液可以显著降低A层、B层和C层土壤的细菌多样性，pH3．5酸处理土壤的细菌多样性降低幅度最大，pH4．5酸处理土壤的降低幅度最小。HCl-NH4Cl酸溶液可显著影响花岗岩土壤细菌的群落结构，并导致土壤细菌的优势种群发生变化，其中，A层土壤细菌优势种群由酸杆菌门（Acidobacteria）转变为变形菌门（Protcobacteria），B层和C层土壤细菌优势种群由变形菌门（Proteobacteria）转变为放线菌门（Actinobacteria）。细菌相对丰度变化特征和主成分分析结果表明，pH3．5、pH4．5和pH5．5三种酸处理之间没有明显差异，但不同层次土壤细菌群落结构对同-pH酸溶液的响应不一致，这是由A、B、C层土壤理化性质的差异性，从而对酸处理的响应不同所致。因此，HCl-NH4Cl酸溶液对土壤细菌群落结构、优势种群和多样性产生的显著影响与土壤的性质密切相关，并反作用于土壤发生、演变及生态系统演替。

英文摘要：

Acid deposition significantly influenced ecological system structure and function, but the research on the effect of acid deposition on soil bacteria community and diversity was less. This study used granite soil profiles （0 - 100cm） suffered serious acid deposition in the subtropical area as research objectives. The batch leaching experiments had been carried with different pH solutions （HCl-NH4Cl, pH = 3.5, 4.5, 5.5） for soil from A profile （0 - 12 cm）, B profile （12 - 50 cm） and C profile （50 - 100 cm）. Then the variability of soil bacterial community structure and diversity were discussed before and after acid treatments. The 16S rRNA genes of soil bacterial were analyzed by the MiSeq High-throughput Sequencing Technique. The results showed that the HC1 - NH4C1 acid solution significantly reduced bacterial diversity at soil A, B and C layers, and soil bacterial diversity suffered the biggest drops at soil pH of 3.5, and the least drops at soil pH of 4.5 treated with acid treatment. The HC1 - NHgC1 acid solution significantly influenced soil bacterial structure and changed soil bacterial dominant population. The dominant population was changed from Acidobacteria to Proteobacteria at soil A layer, and from Proteobacteria to Actinobacteria at soil B and C layers. The change in bacterial relative abundance and the principal component analysis showed that there was no significant variation of soil bacterial community among pH 3.5, pH 4.5 and pH 5.5, but soil bacterial community structure at different soil layers had the same responses to acid solution, which caused by the difference in soil physical and chemical properties among different acid treatments. The significant effects of acid solution on soil bacterial community and dominant population were closely related with soil propriety, and counteracted soil evolution and ecosystem succession.