Labile carbon retention compensates for CO2 released by priming in forest soils

Authors

  • Na Qiao,

    1. Key Laboratory of Tropical Forest Ecology, Chinese Academy of Sciences, Xishuangbanna Tropical Botanical Garden, Yunnan, China
    2. Graduate School of the Chinese Academy of Sciences, Beijing, China
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    • These authors wish to be considered joint first authors.
  • Douglas Schaefer,

    1. Key Laboratory of Tropical Forest Ecology, Chinese Academy of Sciences, Xishuangbanna Tropical Botanical Garden, Yunnan, China
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    • These authors wish to be considered joint first authors.
  • Evgenia Blagodatskaya,

    1. Key Laboratory of Ecosystem Network Observation and Modeling, Chinese Academy of Sciences (CAS), Institute of Geographic Sciences and Natural Resources Research, Beijing, China
    2. Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen, Germany
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  • Xiaoming Zou,

    1. Key Laboratory of Tropical Forest Ecology, Chinese Academy of Sciences, Xishuangbanna Tropical Botanical Garden, Yunnan, China
    2. Institute for Tropical Ecosystem Studies, University of Puerto Rico, Puerto Rico, USA
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  • Xingliang Xu,

    Corresponding author
    1. Key Laboratory of Tropical Forest Ecology, Chinese Academy of Sciences, Xishuangbanna Tropical Botanical Garden, Yunnan, China
    2. Key Laboratory of Ecosystem Network Observation and Modeling, Chinese Academy of Sciences (CAS), Institute of Geographic Sciences and Natural Resources Research, Beijing, China
    • Correspondence: Xingliang Xu, tel. +86 10 64889813, fax +86 10 64889813, e-mail: xuxingl@hotmail.com

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  • Yakov Kuzyakov

    1. Key Laboratory of Ecosystem Network Observation and Modeling, Chinese Academy of Sciences (CAS), Institute of Geographic Sciences and Natural Resources Research, Beijing, China
    2. Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen, Germany
    3. Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany
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Abstract

Increase of belowground C allocation by plants under global warming or elevated CO2 may promote decomposition of soil organic carbon (SOC) by priming and strongly affects SOC dynamics. The specific effects by priming of SOC depend on the amount and frequency of C inputs. Most previous priming studies have investigated single C additions, but they are not very representative for litterfall and root exudation in many terrestrial ecosystems. We evaluated effects of 13C-labeled glucose added to soil in three temporal patterns: single, repeated, and continuous on dynamics of CO2 and priming of SOC decomposition over 6 months. Total and 13C labeled CO2 were monitored to analyze priming dynamics and net C balance between SOC loss caused by priming and the retention of added glucose-C. Cumulative priming ranged from 1.3 to 5.5 mg C g−1 SOC in the subtropical, and from −0.6 to 5.5 mg C g−1 SOC in the tropical soils. Single addition induced more priming than repeated and continuous inputs. Therefore, single additions of high substrate amounts may overestimate priming effects over the short term. The amount of added glucose C remaining in soil after 6 months (subtropical: 8.1–11.2 mg C g−1 SOC or 41-56% of added glucose; tropical: 8.7–15.0 mg C g−1 SOC or 43–75% of glucose) was substantially higher than the net C loss due to SOC decomposition including priming effect. This overcompensation of C losses was highest with continuous inputs and lowest with single inputs. Therefore, raised labile organic C input to soils by higher plant productivity will increase SOC content even though priming accelerates decomposition of native SOC. Consequently, higher continuous input of C belowground by plants under warming or elevated CO2 can increase C stocks in soil despite accelerated C cycling by priming in soils.

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