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Microbial temperature sensitivity and biomass change explain soil carbon loss with warming
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| Abstract |
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| Soil microorganisms control carbon losses from soils to the atmosphere 13 , yet their responses to climate warming are often short-lived and unpredictable 47 . Two mechanisms, microbial acclimation and substrate depletion, have been proposed to explain temporary warming effects on soil micro- bial activity 810 . However, empirical support for either mecha- nism is unconvincing. Here we used geothermal temperature gradients ( > 50 years of field warming) 11 and a short-term experiment to show that microbial activity (gross rates of growth, turnover, respiration and carbon uptake) is intrinsi- cally temperature sensitive and does not acclimate to warm- ing ( + 6 °C) over weeks or decades. Permanently accelerated microbial activity caused carbon loss from soil. However, soil carbon loss was temporary because substrate depletion reduced microbial biomass and constrained the influence of microbes over the ecosystem. A microbial biogeochemical model 12 14 showed that these observations are reproducible through a modest, but permanent, acceleration in microbial physiology. These findings reveal a mechanism by which intrinsic microbial temperature sensitivity and substrate depletion together dictate warming effects on soil carbon loss via their control over microbial biomass. We thus provide a framework for interpreting the links between temperature, microbial activity and soil carbon loss on timescales relevant to Earths climate system. |
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English
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| Source (journal) |
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Nature climate change | |
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2018
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1758-678X
1758-6798
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8:10(2018), p. 885-889
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000445927700019
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30288176
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| Full text (open access) |
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| Full text (publisher's version - intranet only) |
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