侵蚀-沉积作用对黄土高原林地土壤中固碳细菌群落分布特征的影响

In view of the scientific problem that the response law of soil carbon-fixing bacteria to erosion-deposition in the Loess Plateau is unclear,four representative sampling points,including erosion points and deposition points on uncultivated slopes and erosion points and deposition points on Robinia pseudoacacia slopes,were selected in Qiaozigou watershed,Gansu Province.Autotrophic bacteria with carbon-fixing function gene cbbL in soil samples were taken as the research object,and the diversity,distribution characteristics and structural differences of carbon-fixing bacteria communities were studied by high-throughput sequencing technology.The results showed that the diversity and richness of carbon-fixing bacteria on Robinia pseudoacacia slope were significantly lower than those on uncultivated slope(P<0.01).Twenty-one autotrophic bacteria genera with cbbL carbon fixation function genes were identified by sequencing data.These genera belong to three bacterial phyla,including Blastomycetes,Proteobacteria and Actinomycetes.Principal coordinate analysis and cluster analysis show that the composition of autotrophic carbon-fixing bacteria communities in erosion sites and deposition sites under the same slope is similar.Correlation analysis showed that soil total potassium,total nitrogen and pH value were highly correlated with the changes of bacterial community composition.It is found that soil total nitrogen affects soil microbial community to some extent by affecting the availability of organic carbon and pH value,and then affects soil biomass.CbbL gene mainly exists in silt and clay,but there is almost no cbbL gene in sandy soil under different management.The above results show that both vegetation cover and soil treatment will affect soil bacterial community,because soil properties control biogeochemical processes and ecosystem functions.