生物炭添加对半干旱区土壤细菌群落的影响

以半干旱区固原生态试验站生物炭修复4a的表层土壤为对象,采用高通量测序技术研究了不同添加类型（槐树皮生物炭、锯末生物炭）和比例（1%、3%、5%,质量百分比）的生物炭对土壤细菌多样性及群落结构的影响.结果表明,生物炭应用提高了土壤细菌群落的多样性,锯末生物炭优于槐树皮生物炭,且3%锯末生物炭对细菌群落的多样性影响最佳,其香农指数为6.22;优势门主要为放线菌门（Actinobacteria）、变形菌门（Proteobacteria）、绿弯菌门（Chloroflexi）、酸杆菌门（Acidobacteria）和Saccharibacteria,相对丰度共占76.80%~85.31%;优势纲有放线菌纲（Actinobacteria）、α-变形菌纲（Alphaproteobacteria）、酸杆菌纲（Acidobacteria）,其相对丰度占48.13%~57.08%;属水平上,施加生物炭增加了芽孢杆菌属（Bacillus）、硝化螺旋菌属（Nitrospira）的相对丰度,降低了土微菌属（Pedomicrobium）、根瘤菌属（Rhizobium）的相对丰度;层级聚类及冗余分析（RDA）发现,施加生物炭对细菌群落结构有影响,其中,微生物量碳、含水率、铵态氮、有机碳对细菌群落结构的影响较大.细菌优势门与环境因子相关性热图分析表明,铵态氮与放线菌门、绿弯菌门呈显著相关性.铵态氮是影响细菌群落的主要理化因子.

Effects of biochar addition on soil bacterial community in semi-arid region

Using surface soils collected from Guyuan Ecological Experiment Station in Semi-arid Region restored by biochar for 4years as research objects, th effects of two types of biochar (locust tree bark biochar、sawdust biochar) at three different mass percentages (1%、3% and 5%) on soil bacterial community diversities and structures were investigated by using Miseq high-throughput sequencing technology. The results showed that the diversity of soil bacterial community was increased with biochar addition, and the diversities were higher in the treatment with sawdust biochar than that in the treatment with locust tree bark biochar. Further, 3% sawdust biochar addition had the best effect on bacterial community diversities, and its Shannon index was 6.22. The dominant taxa at phyla level were Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria and Saccharibacteria, with relative abundance of 76.80%~85.31%. The dominant taxa at class level were Actinobacteria, Alphaproteobacteria, Acidobacteria, with relative abundance of 48.13%~57.08%. At genus level, the relative abundance of the Bacillus, Nitrospira increased, while the relative abundance of the Pedomicrobium, Rhizobium decreased after biochar treatmetns. Hierarchical clustering and redundancy analysis (RDA) indicated that the application of biochar greatly affected the bacteria community structures. The microbial biomass carbon, water content, ammonium nitrogen (NH₄⁺-N), organic carbon contents had great influences on the variations of bacterial community structure. The heatmap of the correlation between taxa of dominant bacteria and environmental factors further indicated that NH₄⁺-N concentration was significantly correlated with Actinobacteria and Chloroflexi. Therefore, the change in NH₄⁺-N concentration caused by biochar addition was the key factor leading to the variations of soil bacterial communities.