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| Variation in soil properties and bacterial community composition of different habitat soils in the Yellow River Delta, China |
| Received:February 23, 2022 Revised:June 20, 2022 |
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| KeyWord:Yellow River Delta;salinization;Suaeda salsa;ecological network;keystone taxa |
| Author Name | Affiliation | E-mail | | WU Tongtong | Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
State Experimental Station of Agro-Ecosystem in Fengqiu, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | XU Jisheng | State Experimental Station of Agro-Ecosystem in Fengqiu, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | ZHOU Yunpeng | State Experimental Station of Agro-Ecosystem in Fengqiu, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | CHEN Meiqi | State Experimental Station of Agro-Ecosystem in Fengqiu, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | ZHOU Tantan | State Experimental Station of Agro-Ecosystem in Fengqiu, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | GUO Wei | State Experimental Station of Agro-Ecosystem in Fengqiu, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | CHEN Jinlin | Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China | jlchen@njfu.edu.cn | | ZHAO Bingzi | State Experimental Station of Agro-Ecosystem in Fengqiu, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | bzhao@issas.ac.cn |
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| Abstract: |
| The relationship between soil salinization and properties and their interactions with microbial communities and functions are important for understanding the biogeochemical cycles and ecosystem function regulation in saline wetlands. However, the impacts of salinity on soil functions remain elusive. The keystone taxa and their function in various saline habitats are not fully understood. In this study, soil samples were collected from four different habitats from the coast to the inland region in the Yellow River Delta： High salinity （S1） , moderate salinity（S2） , low salinity（S3） , and non-saline soils（S4） . The four habitat soils displayed decreasing salinity from the coast moving toward the inland. In addition to electrical conductivity（EC） , other soil properties, including soil nutrients and microbial biomass carbon（MBC） , were determined. The bacterial diversity and structure were investigated with 16S rRNA gene sequencing to identify the keystone species in the specific habitat. Results showed that EC, representing salinity, varied most among the soil properties from the coast to the inland. As salinity decreased, the contents of NO3--N and MBC considerably increased, and those of soil organic carbon （SOC）and total nitrogen（TN）gradually increased, whereas the contents of total potassium（TK） , available potassium（AK） , and available phosphorus（AP） were significantly decreased. The bacterial communities in the four different habitats were always dominated by Proteobacteria, Planctomycetes, and Actinobacteria, accounting for a relative abundance above 60%. The bacterial communities in S1 samples greatly differed from those in the other three habitats, with more specialist abundant genera in S1 samples and more abundant genera shared among the other three habitats. More importantly, each habitat soil featured specialist keystone taxa. For the S1 samples, the keystone species included OTU002085（phosphate-solubilizing bacteria Vibrio） and OTU000979（Geothermobacter involved in dissimilatory Fe（Ⅲ）reduction）. For the S2 samples, the keystone species included OTU000585（Candidatus_Entotheonella） and OTU000199（Amaricoccus） ; Candidatus_Entotheonella can promote nitrification, whereas Amaricoccus can degrade complex organic matter. For the S3 samples, the keystone species included OTU000015（Methyloceanibacter）and OTU000138（Luteolibacter） . Methyloceanibacter was a key player in the global carbon cycle and Luteolibacter inhibits pathogens. For the S4 samples, the keystone species included OTU001724（Achromobacter） and OTU000841（Gemmata） . Achromobacter species were efficient in biological nitrogen fixation, and Gemmata elevated urease activity to increase organic matter decomposition. Most of these keystone OTUs were significantly negatively correlated with EC and NO - 3-N content, and positively correlated with AK content. For the total bacterial community, MBC was the most influencing factor, which explained 62.5% of the variation, followed by EC（11.7%）and AP（6.5%） , as revealed using multiple regression tree analysis（MRT） . These results indicate that the microbial biomass is extremely sensitive to variations in habitats with different salinity. Salinization does not necessarily lead to complete land degradation but has strong influence on the composition of soil bacterial communities, especially of the keystone taxa. Therefore, the keystone taxa should be considered to assess the ecosystem function. |
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