Responses of the functional structure of soil microbial community to livestock grazing in the Tibetan alpine grassland

Authors

  • Yunfeng Yang,

    Corresponding author
    • State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China
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  • Linwei Wu,

    1. State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China
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  • Qiaoyan Lin,

    1. Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
    2. Key Laboratory of Adaption and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
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  • Mengting Yuan,

    1. State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China
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  • Depeng Xu,

    1. State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China
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  • Hao Yu,

    1. Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, OK, USA
    2. State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China
    3. College of Resource and Environment Engineering, Liaoning Technical University, Buxin, Liaoning, China
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  • Yigang Hu,

    1. Key Laboratory of Adaption and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
    2. Shapotou Desert Experiment and Research Station, Cold and Arid Regions and Environmental & Engineering Research Institute, Chinese Academy of Sciences Lanzhou, China
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  • Jichuang Duan,

    1. Key Laboratory of Adaption and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
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  • Xiangzhen Li,

    1. Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
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  • Zhili He,

    1. Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, OK, USA
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  • Kai Xue,

    1. Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, OK, USA
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  • Joy van Nostrand,

    1. Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, OK, USA
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  • Shiping Wang,

    1. Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
    2. Key Laboratory of Adaption and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
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  • Jizhong Zhou

    1. State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China
    2. Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, OK, USA
    3. Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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Correspondence: Yunfeng Yang, tel. +86-10-62784692, fax +86-10-62785687, e-mail: yangyf@tsinghua.edu.cn

Abstract

Microbes play key roles in various biogeochemical processes, including carbon (C) and nitrogen (N) cycling. However, changes of microbial community at the functional gene level by livestock grazing, which is a global land-use activity, remain unclear. Here we use a functional gene array, GeoChip 4.0, to examine the effects of free livestock grazing on the microbial community at an experimental site of Tibet, a region known to be very sensitive to anthropogenic perturbation and global warming. Our results showed that grazing changed microbial community functional structure, in addition to aboveground vegetation and soil geochemical properties. Further statistical tests showed that microbial community functional structures were closely correlated with environmental variables, and variations in microbial community functional structures were mainly controlled by aboveground vegetation, soil C/N ratio, and NH4+-N. In-depth examination of N cycling genes showed that abundances of N mineralization and nitrification genes were increased at grazed sites, but denitrification and N-reduction genes were decreased, suggesting that functional potentials of relevant bioprocesses were changed. Meanwhile, abundances of genes involved in methane cycling, C fixation, and degradation were decreased, which might be caused by vegetation removal and hence decrease in litter accumulation at grazed sites. In contrast, abundances of virulence, stress, and antibiotics resistance genes were increased because of the presence of livestock. In conclusion, these results indicated that soil microbial community functional structure was very sensitive to the impact of livestock grazing and revealed microbial functional potentials in regulating soil N and C cycling, supporting the necessity to include microbial components in evaluating the consequence of land-use and/or climate changes.

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