林冠受损对小坑林场土壤固碳微生物群落结构的影响

Effects of canopy damage on soil CO_2 fixation bacterial community structure in Xiaokeng forest farm

【目的】以典型南亚热带常绿阔叶林小坑林场土壤为研究对象,模拟2008年冰雪灾害对森林造成的损伤设置实验,分析不同林冠开度和凋落物输入量对土壤固碳微生物群落结构的影响。【方法】试验设置对照(CN)、损伤处理+移除处理枝叶(TR)、损伤处理+保留处理枝叶(TD)、未处理+添加处理枝叶(UD)4个处理,受损处理一年后,采用MiSeq高通量测序技术对土壤固碳微生物的功能基因cbbL进行测序分析。【结果】通过生物信息学及统计学分析表明,森林林冠损伤后林冠开度和凋落物输入量增加,导致土壤固碳微生物种群数量降低,多样性增加,群落结构也受到影响,亚硝化螺菌属(Nitrosospira)明显增加,成为优势种群,而原来的优势菌群慢生根瘤菌属(Bradyrhizobium)明显减少。主成分分析(PCA)表明,与对照相比,其他3个样地的土壤固碳微生物结构均发生明显改变。【结论】模拟林冠损伤处理一年后,凋落物的大量骤然输入和林冠开度增大提高了土壤固碳微生物群落多样性,但降低了其种群数量,影响了土壤固碳微生物群落结构,这为进一步的研究提供了依据。

[Objective] We designed and did experiments to simulate canopy damage in Xiaokeng forest farm, and to analyze the impact of canopy openness and litter input on soil CO2 fixation bacteria community structure. [Methods] A manipulative field experiment was conducted to study the effects of four different forms： control plots, damage-removal and treatment, damage-retention and processing, and untreated-add foliage treatment. Soil CO2 fixation bacteria community structure was measured by MiSeq analyses after a year of canopy damage. [Results] Based on bioinformatics and statistical analyses, community richness of soil CO2 fixation bacteria decreased and diversity increased under the influence of litter inputs and canopy openness. Nitrosospira increased significantly and became the dominant population, whereas the original dominant group of Bradyrhizobium decreased. Principal component analysis shows that community structures of soil CO2 fixation bacteria were changed. [Conclusion] A large number of litter inputs and increased canopy openness improved diversity of soil CO2 fixation bacteria, but decreased their community richness, and affected their community structure.