带状采伐对毛竹林土壤细菌群落结构及多样性的影响

【目的】研究带状采伐后毛竹(Phyllostachys edulis)林土壤细菌群落结构及多样性的变化,认识带状采伐对毛竹林土壤生态系统的影响,为利用带状采伐实现毛竹林规模化经营提供指导。【方法】对毛竹林进行不同宽度(3、9、15 m)的带状采伐,25 d后采集样地内土壤样品,采用Illumina MiSeq 高通量测序技术分析土壤细菌特定基因片段V3-V4区域,鉴定菌种类群,预测细菌功能,并结合7种土壤养分指标(有机质、全氮、全磷、全钾、碱解氮、有效磷、速效钾)的测定结果,探讨带状采伐对毛竹林地土壤细菌群落及土壤养分的影响。【结果】随着采伐宽度的增加,土壤有效磷、全钾、速效钾含量降低,土壤有机质、全氮、碱解氮含量先增后降。适当采伐可以提高土壤肥力,但采伐宽度超过一定限度后,土壤肥力降低,速效养分含量减少。不同带状采伐对毛竹林土壤中细菌类群的丰度、多样性、均匀度的影响各不相同;3 m采伐宽度的毛竹林地内土壤细菌群落丰富度最高,且物种分布最均匀,随着采伐宽度的增大,其毛竹林地内的细菌群落丰富度和物种均匀度均降低,当采伐宽度超过9 m时,群落间的物种组成变化差异减小。带状采伐后变形菌门(Proteobacteria)相对丰度增多,酸杆菌门(Acidobacteria)、绿湾菌门(Chloroflexi)相对丰度减少,这3种菌门同放线菌门(Actinobacteria)一起占据着毛竹林带状采伐土壤细菌群落种的主要地位,对土壤中碳(C)、氮(N)元素固定及其他养分的转化分解发挥着重要的作用。带状采伐后土壤细菌群落代谢通路中最重要的是碳水化合物代谢和氨基酸代谢,说明带状采伐后土壤细菌的优势功能主要集中在C、N两种元素的固定和转化。【结论】毛竹林带状采伐对土壤细菌群落结构及多样性产生显著影响,3 m宽度的带状采伐能够增加细菌类群的丰度、多样性、均匀度以及土壤养分含量,当采伐宽度增大,上述各项指标降低;综合分析表明带状采伐后土壤微生物类群主要参与C、N元素的固定和转化的相关功能通路。

Influence of strip cutting management on soil bacterial community structure and diversity in Phyllostachys edulis stands

【Objective】In order to provide scientific guidance for understanding the management of bamboo(Phyllostachys edulis) forests stands and restoration of soil ecosystems, the impact of strip cutting on soil bacterial community structure and diversity was studied. 【Method】Soil samples were collected from P. edulis stands of different widths(3, 9 and 15 m) after 25 d at Yixing, Jiangsu Province. V3-V4 regions were sequenced using the Illumina MiSeq High Throughput Sequencing to identify soil bacteria and predict functional groups. Soil organic matter, total N, total P, total K, available N, available P and available K were analyzed using standard methods.【Result】With the increase in cutting width, the contents of soil available P, total K, and available K decreased, while the contents of soil organic matter, and total and available N initially increased and then decreased. The selection of the appropriate cutting width could improve soil fertility, but when the cutting width exceeded a certain limit, the soil fertility and the content of available nutrients decreased. Strip cutting management had an impact on the soil bacterial abundance, diversity and evenness. At a cutting width of 3 m, the soil bacterial community was richer, and species distribution was more uniform than others. With the increase in the cutting width, the bacterial community richness and uniformity in the P. edulis forest decreased. When the cutting width exceeded a certain level, the difference in species composition between communities decreased. Strip cutting increased the diversity of Proteobacteria and decreased that of Acidobacteria and Chloroflexi. Proteobacteria, Actinobacteria, Acidobacteria and chloroflexi belong to the same functional group in the stripped soil of the bamboo forest, stimulating carbon and nitrogen fixation and the transformation and decomposition of other nutrients. The main metabolic pathways after strip cutting were carbohydrate and amino acid production.【Conclusion】Comprehensive analyses showed that strip cutting of P. edulis forests had a significant influence on the soil bacterial community structure and diversity. The shorter width(3 m) strip cutting could increase the abundance and diversity of soil bacteria and nutrient content. However, with the increase in strip-cutting width, the various indicators decreased. After strip cutting, soil microbial groups mainly acted on the fixation, decomposition, and transformation of C and N.