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

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. Microbial functional diversity decreased in response to warming, whereas 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 N 2O 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 metabolicmore » 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.« less
 [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [1]
  1. Tsinghua Univ., Beijing (China)
  2. Chinese Academy of Sciences (CAS), Beijing (China); CAS Center for Excellence in Tibetan Plateau Earth Science, Beijing (China)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Chicago, Chicago, IL (United States); Zhejiang Univ., Hangzhou (China)
  4. Chinese Academy of Sciences (CAS), Xining (China)
  5. Chinese Academy of Sciences (CAS), Xining (China); Chinese Academy of Sciences (CAS), Lanzhou (China)
  6. Chinese Academy of Sciences (CAS), Sichuan (China)
  7. Univ. of Oklahoma, Norman, OK (United States)
  8. Tsinghua Univ., Beijing (China); Univ. of Oklahoma, Norman, OK (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; SC0004601
Accepted Manuscript
Journal Name:
The ISME Journal
Additional Journal Information:
Journal Volume: 9; Journal Issue: 9; Journal ID: ISSN 1751-7362
Nature Publishing Group
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Country of Publication:
United States
OSTI Identifier: