Pedosphere 31(6): 912--922, 2021
ISSN 1002-0160/CN 32-1315/P
©2021 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Lowered water table causes species substitution while nitrogen amendment causes species loss in alpine wetland microbial communities
Yuntao LI1,2, Jin-Sheng HE3,4, Hao WANG4, Jizhong ZHOU5,6,7, Yunfeng YANG5, Haiyan CHU1,2
1State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008 (China)
2University of Chinese Academy of Sciences, Beijing 100049 (China)
3Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China)
4State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000 (China)
5State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084 (China)
6Institute for Environmental Genomics, Department of Microbiology and Plant Biology and School of Civil Engineering and Environmental Sciences, University of Oklahoma, Norman OK 73019 (USA)
7Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley CA 94270 (USA)
ABSTRACT
      Alpine wetlands are hotspots of carbon (C) storage and methane emission, and they could be key contributors to global warming. In recent years, rapid warming has lowered the water table in alpine wetlands on the Tibetan Plateau, concurrent with intensified nitrogen (N) deposition via anthropogenic activities. We carried out a field experiment to investigate the ecological impacts of these two factors on soil bacterial and functional communities, which are essential drivers of greenhouse gas emissions. Nitrogen amendment alone decreased the phylogenetic alpha-diversity of bacterial communities which could be offset by lowered water table. In contrast, microbial functional alpha-diversity, revealed by a high-throughput microarray, remained unchanged. Both bacterial and functional beta-diversity responded to lowered water table, but only bacterial community responded to N amendment. The alpha-Proteobacteria, beta-Proteobacteria, and Bacteroidetes were the major responsive bacterial lineages, and C degradation, methanogenesis, alkaline shock, and phosphorus oxidation were the major responsive functional processes. Partitioning analysis revealed that N amendment changed bacterial community structure mainly via species loss processes but did not affect bacterial functional communities, with soil pH and ammonium as the key factors influencing changes in bacterial community structure. Conversely, lowered water table altered bacterial and functional communities through species substitution processes linked to soil pH and soil moisture. According to our results, the response mechanisms of microbial communities to lowered water table and N amendment are fundamentally different in alpine wetlands.
Key Words:  alpha-diversity,bacterial community,beta-diversity,microbial functional community,N amendment,water table lowering
Citation: LI Y T, He J S, Wang H, Zhou J Z, Yang Y F, Chu H Y. 2021. Lowered water table causes species substitution while nitrogen amendment causes species loss in alpine wetland microbial communities. Pedosphere. 31(6)
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