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| Impact of typical agricultural land use on the characteristics of soil microbial communities in the Nyingchi region of southeastern Tibet |
| Received:July 27, 2019 |
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| KeyWord:soil bacterial community;soil fungal community;high-throughput pyrosequencing;land use type;cropland;Tibetan Plateau |
| Author Name | Affiliation | E-mail | | ZHANG Xu-bo | Key Laboratory of Ecosystem Network Observation and Modeling/Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China | | | XU Meng | Key Laboratory of Ecosystem Network Observation and Modeling/Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China | xumeng@igsnrr.ac.cn | | SHI Fei | College of Agriculture, Guizhou University, Guiyang 550025, China | |
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| Abstract: |
| Changes in the soil microbial community can have a significant impact on ecosystem functionality and stability. The Nyingchi region, which is located in the southeastern part of the Tibetan Plateau, has a long history of agricultural cultivation and land use. However, the impact of agricultural land use on soil microbial communities remains unclear. Therefore, it is necessary to investigate the effect of agricultural land use on soil microbial communities and the factors that control the variations in microbial communities. This will help to understand the influence of agricultural land use on the stability of ecosystems in southeastern Tibet and provide a scientific basis for the sustainable management of agricultural soils in this region. In the present study, soil samples were collected from two typical agricultural land use types(cropland and pasture)and native forest in the Nyingchi region of southeastern Tibet. Phospholipid fatty acids(PLFA)analysis and MiSeq pyrosequencing, in combination with analyses of soil properties, were conducted to analyze the differences in the biomass, diversity, and composition of microbial communities in soils under agricultural land use types compared with those of native forest soil and to determine the controlling factors of the variation in microbial communities. The total PLFA concentration indicated that the microbial biomass in cropland and pasture soils decreased by 38.7%~51.8% compared with that of native forest soils. The decreases in the PLFA concentrations of Gram-positive bacteria, Gram-negative bacteria, actinomycetes, and fungi under agricultural land use were 26.1%~47.6%, 40.0%~61.1%, 44.1%~60.6%, and 5.2%~31.3%, respectively. The diversity of the soil fungal community was markedly decreased in cropland soil with 53.0% and 71.4% lower richness index(Chao)and Shannon diversity index values, respectively, compared with those of native forest soil, while the decrease in the richness and Shannon diversity of the bacterial community was 15.7% and 5.1%, respectively. The relative abundance of Actinobacteria(bacterial phylum)was significantly increased in cropland soil, whereas those of Planctomycetes, Chloroflexi, and Firmicutes were reduced compared with those of pasture and forest soil. The relative abundances of Bacteroidetes and Cyanobacteria were promoted in pasture soil compared with those of the other land use types. The relative abundance of Agaricomycetes(fungal class)in cropland and pasture soils was 23 and 19 times greater than that in native forest soil, thereby suggesting the significant dominance of Agaricomycetes in the fungal community under agricultural land use. Meanwhile, the relative abundances of Ascomycota and Zygomycota(fungal phyla)in cropland and pasture soils were 67.7%~89.6% and 58.7%~67.4% lower than those of native forest soil, respectively. The distance-based redundancy analysis showed that there were significant differences in the structure of the bacterial and fungal communities among the three land use types. Changes in the microbial biomass, diversity indexes, and community composition were strongly influenced by soil properties such as pH, soil organic carbon, and the C/N ratio. In addition, the response of the soil fungal community to these changes in soil variables due to agricultural land use was more sensitive than that of the bacterial community. The results of the present study showed that typical agricultural land use in the Nyingchi region exerts a significant impact on the soil microbial community by decreasing the microbial biomass and diversity and altering the composition and structure of the soil bacterial and fungal communities. Furthermore, the soil fungal community was more sensitive to agricultural land use than the soil bacterial community. Therefore, there is a great need to emphasize the physiological and ecological understanding of soil bacterial and fungal taxa that could be sensitive to agricultural land use and the potential influence of these taxa on the functionality of the ecosystem in southeastern Tibet. |
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