关键词: 环境选择, 扩散限制, 关帝山, 针叶林, 高通量测序, 细菌群落结构

Abstract: [Objective] Soil microorganisms drive the biogeochemical processes of carbon, nitrogen, phosphorus and sulfur in soil, and play a key role in maintaining soil carbon sink and forest ecosystem function. In this study, we analysed effects of environmental and spatial factors on the soil bacterial community structure in cold-temperature coniferous forest,which would provide the oretical basis for making management measures for the local forest ecosystem.[Method] This research analyzed four soil bacteria communities (LpMC1, LpMC2, PwMC and PtMC) in three coniferous forest types, including Larix gmelinii var. principis-rupprechtii forest, Picea wilsonii forest and Pinus tabulaeformis forest in the Pangquangou Nature Reserve in Guandi Mountains with Illumina high-throughput sequencing technology. Meanwhile, soil enzyme activity and soil physicochemical properties were determined to analyze the relationship between bacteria community structure and forest types as well as soil environmental factors.[Result] 1) In the region, Proteobacteria, Bacteroidetes, Actinobacteria, Verrucomicrobia, Planctomycetes, Acidobacteria, Firmicutes, Gemmatimonadetes, Chloroflexi, Chlamydiae and Nitrospirae were dominant bacteria groups; 2) Redundancy analysis between the relative abundance of dominant bacterial groups and soil environmental parameters showed that soil moisture content, carbon and nitrogen ratio, pH and soil enzyme activity were the main factors that affected soil bacterial community structure; Proteobacteria and Bacteroidetes were relatively more suitable for living in the acid, humidity and nutrition rich status soil, and active carbon was the main carbon source, while Actinobacteria, Planctomycetes and Chloroflexi were more dominant in alkaline, drought and poor nutrient soil, and resistant carbon was the main carbon source.3) Alphadiversity analysis showed that there existed difference in diversity of soil bacteria community between the four coniferous forests.Low richness and high diversity were observed in P. tabulaeformis forest (PtMC) with poor nutrient while high richness and low diversity were observed in L. gmelinii var.principis-rupprechtii forest (LpMC1) on high altitude with rich nutrient.4) Beta diversity analysis showed that bacteria community structures of P. wilsonii forest and P. tabuliformis forest were the most similar while L. gmelinii var.principis-rupprechtii forests on different elevations had the same trend.[Conclusion] Environmental selection and dispersal limitation led to the significant differences of structure and biodiversity among soil bacterial communities from coniferous forests in the study area. Hereby, through the development of different forest management measures, we can change the soil environment,and then optimize the soil bacterial community structure, improve the soil carbon sequestration, and promote the recycling of nutrients such as nitrogen, sulfur and phosphorus in improving soil fertility.

Key words: environmentalselection, dispersal limitation, Guandi Mountains, coniferous forest, high-throughput sequencing, bacterial community structure