毛竹入侵马尾松林的土壤菌群多样性变化

为揭示毛竹入侵邻域林分过程中对土壤细菌群落多样性变化的影响,以马尾松林为研究对象,采集纯毛竹林、竹针混交林和常绿针叶(马尾松)混交林3类样地的混合土样,基于高通量测序技术分析土壤细菌群落多样性和结构变化.结果表明: 研究期间共得到细菌类群39门88纲134目160科511属;在门的分类水平上,与竹针混交林、常绿针叶混交林相比,纯毛竹林酸杆菌门所占比例显著较低,而放线菌门、拟杆菌门、TM7和衣原体门所占比例较高;在属的分类水平上,相对于纯毛竹林,竹针混交林和常绿针叶混交林均有多属表现出所占比例显著上升或下降,单独出现在竹针混交林或常绿针叶混交林且所占比例在0.005%～0.1%的非优势属有130属;α多样性指数均表现为常绿针叶混交林>竹针混交林>纯竹林,且纯竹林与两者均有显著差异,而常绿针叶混交林和竹针混交林之间差异不显著.PCoA分析表明,毛竹入侵对土壤细菌的种群多样性和群落结构产生了影响;所占比例小于0.1%的非优势菌群门分类水平的百分比特征与土壤环境梯度(水溶性有机氮和硝态氮)之间有显著相关性,两者对毛竹入侵马尾松林后土壤细菌群落的非优势种群影响巨大,具有重要的参考价值.

Variation of soil bacterial diversity after the invasion of Phyllostachys edulis into Pinus massoniana forest

To identify the variation in soil bacterial community diversity brought by the invasion of Phyllostachys edulis into Pinus massoniana forest, we collected mixed soil samples from three types of forests, including a pure Ph. edulis forest, a mixed Ph. edulis and conifers (P. massoniana) fore-st, and a mixed forest of evergreen broadleaves and conifers. Samples were analyzed by high-throughput sequencing for measuring the soil bacterial community diversity and structure. The results showed that the bacterial communities comprised of 511 genera, 160 families, 134 orders, 88 classes, and 39 phyla. The proportion of Acidobateria in the pure Ph. edulis forest was significantly lower and the proportions of Actinobacteria, Bacteroidetes, TM7, and Chlamydiae were significantly higher than that in other forests. Meanwhile, various genera showed significant differences in proportions in both the mixed forests when compared with their corresponding proportions in the pure Ph. edulis forest. There were 130 non-dominant genera presented alone in each of the two mixed forests, at proportions between 0.005% and 0.1%. The pure Ph. edulis forest had the lowest α diversity, while that of the mixed Ph. edulis and evergreen broadleaf forest was intermediate, and that of the mixed evergreen broadleaf and coniferous forest was the highest. The index of α diversity followed evergreen coniferous mixed forest > bamboo needle mixed forest > pure bamboo forest, and the diffe-rence between the mixed Ph. edulis and evergreen broadleaf forest and the mixed evergreen broadleaf and coniferous forest was insignificant. The PCoA results revealed that the invasion of Ph. edulis affected the population diversity and community structure of soil bacteria. There was a significant correlation between the percentage of non-dominant bacterial phyla in the soil (less than 0.1% of the proportion) and the soil environmental gradient such as water-soluble organic nitrogen and nitrate. Water-soluble organic nitrogen and nitrate had strong effects on the non-dominant bacterial population in the soil following the invasion of Ph. edulis into the P. massoniana forest. These findings would serve as important references for further related studies.