Apparent thermal acclimation of soil heterotrophic respiration mainly mediated by substrate availability |
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Authors: | Yanghui He Xuhui Zhou Zhen Jia Lingyan Zhou Hongyang Chen Ruiqiang Liu Zhenggang Du Guiyao Zhou Junjiong Shao Junxia Ding Kelong Chen Iain P Hartley |
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Institution: | 1. Northeast Asia ecosystem Carbon sink research Center (NACC), Center for Ecological Research, Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, School of Forestry, Northeast Forestry University, Harbin, China;2. Center for Global Change and Ecological Forecasting, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China;3. College of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, China;4. Qinghai Province Key Laboratory of Physical Geography and Environmental Process, College of Geographic Science, Qinghai Normal University, Xining, China;5. Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK |
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Abstract: | Multiple lines of existing evidence suggest that increasing CO2 emission from soils in response to rising temperature could accelerate global warming. However, in experimental studies, the initial positive response of soil heterotrophic respiration (RH) to warming often weakens over time (referred to apparent thermal acclimation). If the decreased RH is driven by thermal adaptation of soil microbial community, the potential for soil carbon (C) losses would be reduced substantially. In the meanwhile, the response could equally be caused by substrate depletion, and would then reflect the gradual loss of soil C. To address uncertainties regarding the causes of apparent thermal acclimation, we carried out sterilization and inoculation experiments using the soil samples from an alpine meadow with 6 years of warming and nitrogen (N) addition. We demonstrate that substrate depletion, rather than microbial adaptation, determined the response of RH to long-term warming. Furthermore, N addition appeared to alleviate the apparent acclimation of RH to warming. Our study provides strong empirical support for substrate availability being the cause of the apparent acclimation of soil microbial respiration to temperature. Thus, these mechanistic insights could facilitate efforts of biogeochemical modeling to accurately project soil C stocks in the future climate. |
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Keywords: | heterotrophic respiration microbial adaptation nitrogen addition substrate depletion warming |
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