泥石流滩地引洪淤地改造后种植玉米对土壤细菌群落结构特征的影响

Soil bacterial community structure of debris flow waste⁃shoal land improving by silting with flood and planting corn

【目的】研究泥石流滩地改造对土壤细菌群落结构的影响,为泥石流滩地利用提供科学依据。【方法】采用客土、引洪漫淤改造泥石流滩地,随后种植玉米,基于对土壤细菌的16S测序分析土壤细菌群落多样性,采用随机森林模型预测关键OTU,研究土壤细菌群落结构的变化。【结果】①泥石流滩地土壤细菌以变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、拟杆菌门(Bacte⁃roidetes)和酸杆菌门(Acidobacteria)为主,相对丰度达75%,其中变形菌门最多,相对丰度40%以上。②引洪漫淤(SY)、客土后引洪漫淤(TY)种植玉米对泥石流滩地土壤细菌群落结构有显著影响,土壤细菌OTU丰度的数量级降低,独有OTU数量低于无改造土壤(SS)。③与SS相比,SY可促进土壤细菌物种数增加,改变土壤细菌关键物种的丰度,物种多样性和均匀度降低;TY可使土壤细菌物种数显著降低,重新配置土壤群落结构。④SY对于总方差的独立解释比例最大(34.38%),引洪漫淤对土壤细菌群落结构的直接效应显著。⑤泥石流滩地土壤细菌群落结构改变与其中2.68%的OTU有紧密关联,依据重要性排序,前6个OTU属于变形菌门(2个不同科)、酸杆菌门、疣微菌门(Verrucomicrobia)、浮霉菌门(Planctomycetes)和Candidatus_Saccharibacteria。【结论】引洪漫淤对泥石流滩地土壤细菌群落结构的直接效应显著,结合客土、玉米种植有利于重新配置土壤细菌群落结构,维持细菌群落结构稳定性。

【Objective】The present paper aimed to study the effects of soil reconstruction and improvement on soil bacterial community struc⁃ture of debris flow waste⁃shoal land,providing a scientific basis for the utilization of debris flow waste⁃shoal land.【Method】The soil of debris flow waste⁃shoal land was improved by replacing with out⁃soil and silting with flood,and then planted corn on it.Based on 16S sequencing of soil bacteria,we analyzed the bacterial community diversity.To study the structural characteristics of soil bacterial community,we used the random forest model to predict the key OTUs.【Result】(i)The soil bacteria in the debris flow wasteshoal land were mainly involved by Proteobacteria,Actinobacteria,Bacteroidetes and Acitobacterium.The total relative abundance of the four bacterial species was 75%,among which Proteobacteria was the most abundant and the relative abundance was more than 40%.(ii)Corn planting after silting with flood(SY)and corn planting after replacing with outsoil and silting with flood(TY)had significant impact on the soil bacterial community structure of debris flow waste⁃shoal land.The bacteria of soil OTU abundance decreased by the order of magnitude,and the number of unique OTUs was lower than that of unmodified soil(SS).(iii)Compared with SS,SY increased the number of soil bacterial species,and changed the abundance of key species of soil bacteria,and reduced species diversity and uniformity.TY could significantly reduce the number of soil bacterial species,and reconfigured the soil community structure.(iv)SY had the largest proportion of independent explanations for the total variance(34.38%),and the direct effect of silting with flood on soil bacterial community structure was significant.(v)The structure of soil bacterial community was closely related to 2.68%of the OTUs.According to the importance,the top 6 OTUs belonged to Proteobacteria(two different families),Ateobacteria,Verrucomicrobia,Planctomycetes and Candidatus_Saccharibacteria.【Conclusion】The direct effect of silting with flood on soil bacterial community structure in debris flow waste⁃shoal land is significant.After replacing with outsoil,silting with flood and the planting corn is conducive to reconfiguring soil bacterial community structure and maintaining the stability of soil community structure.