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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2019-167
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-167
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 10 May 2019

Submitted as: research article | 10 May 2019

Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Biogeosciences (BG) and is expected to appear here in due course.

Past aridity’s effect on carbon mineralization potentials in grassland soils

Zhenjiao Cao1,2, Yufu Jia1, Yue Cai1,2, Xin Wang1,2, Huifeng Hu1, Jinbo Zhang3, Juan Jia1, and Xiaojuan Feng1,2 Zhenjiao Cao et al.
  • 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • 2College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
  • 3School of Geography Sciences, Nanjing Normal University, Nanjing 210023, China

Abstract. Mineralization potential is a key property for assessing carbon substrate’s degradability and mineralization in biogeochemical models and studies. While mineralization potential is widely examined under controlled conditions, whether and how it is influenced by the past aridity of sample’s origins remain poorly constrained, which is important for an accurate assessment and prediction of future CO2 emissions. Here we collect top- and subsoils from different aridity regimes along a 2100-km grassland transect of northern China and conduct a 91-day decomposition experiment with and without the addition of 13C-labeled leaf litter under controlled temperature and moisture. CO2 release from both soil organic carbon (SOC) and fresh litter is measured along with microbial biomass, extracellular enzyme activities, soil and mineral properties. We find that neither microbial carbon use efficiency nor biomass-normalized metabolic quotient (qCO2) is related to the aridity of sampling sites. However, both fresh litter and SOC display the highest mineralization potentials in soils originating from the driest site. Using pathway analysis, we demonstrate that past aridity’s effect is mediated by differential mechanisms for substrates of varied complexity. While microbial biomass plays a more important role in the decomposition of fresh litter, enzyme-catalyzed extracellular reactions predominantly govern the mineralization of SOC. Our findings provide novel evidence on the mechanisms underlying past aridity’s effect on the mineralization potentials of organic matter with different qualities, which has significant implications for assessing and modelling decomposition in different aridity regimes.

Zhenjiao Cao et al.
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Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Zhenjiao Cao et al.
Zhenjiao Cao et al.
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Short summary
Using pathway analysis, we demonstrate that past aridity’s effect is mediated by differential mechanisms for substrates of varied complexity. While microbial biomass plays a more important role in the decomposition of fresh litter, enzyme-catalyzed extracellular reactions predominantly govern the mineralization of SOC. Our findings have significant implications for assessing and modelling decomposition in different aridity regimes.
Using pathway analysis, we demonstrate that past aridity’s effect is mediated by differential...
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