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ISME J. 2015 Sep;9(9):2012-20. doi: 10.1038/ismej.2015.19. Epub 2015 Feb 17.

The microbe-mediated mechanisms affecting topsoil carbon stock in Tibetan grasslands.

Author information

1
State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China.
2
1] Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China [2] CAS Center for Excellence in Tibetan Plateau Earth Science, Beijing, China.
3
1] Institute of Genomic and Systems Biology, Argonne National Laboratory, Argonne, IL, USA [2] Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA [3] College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China.
4
Key Laboratory of Adaption and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China.
5
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.
6
Key Laboratory of Environmental and Applied Microbiology; Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Sichuan, China.
7
Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA.
8
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 Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA [3] Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA [4] Collaborative Innovation Center for Regional Environmental Quality, School of Environment, Tsinghua University, Beijing, China.

Abstract

Warming has been shown to cause soil carbon (C) loss in northern grasslands owing to accelerated microbial decomposition that offsets increased grass productivity. Yet, a multi-decadal survey indicated that the surface soil C stock in Tibetan alpine grasslands remained relatively stable. To investigate this inconsistency, we analyzed the feedback responses of soil microbial communities to simulated warming by soil transplant in Tibetan grasslands. Whereas microbial functional diversity decreased in response to warming, microbial community structure did not correlate with changes in temperature. The relative abundance of catabolic genes associated with nitrogen (N) and C cycling decreased with warming, most notably in genes encoding enzymes associated with more recalcitrant C substrates. By contrast, genes associated with C fixation increased in relative abundance. The relative abundance of genes associated with urease, glutamate dehydrogenase and ammonia monoxygenase (ureC, gdh and amoA) were significantly correlated with N2O efflux. These results suggest that unlike arid/semiarid grasslands, Tibetan grasslands maintain negative feedback mechanisms that preserve terrestrial C and N pools. To examine whether these trends were applicable to the whole plateau, we included these measurements in a model and verified that topsoil C stocks remained relatively stable. Thus, by establishing linkages between microbial metabolic potential and soil biogeochemical processes, we conclude that long-term C loss in Tibetan grasslands is ameliorated by a reduction in microbial decomposition of recalcitrant C substrates.

PMID:
25689025
PMCID:
PMC4542033
DOI:
10.1038/ismej.2015.19
[Indexed for MEDLINE]
Free PMC Article

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