Physicochemical Protection Outweighs Microbial Carbon Use Efficiency in Regulating Soil Organic Carbon Across an Aridity Gradient
Abstract
Microbial carbon use efficiency (CUE) has been proposed as a critical determinant of soil organic carbon (SOC) dynamics, yet its relative importance compared with plant carbon inputs, edaphic conditions, microbial attributes, and physicochemical protection remains poorly understood. Here, we conducted large-scale soil samplings across a 3000-km aridity gradient on the Tibetan Plateau to evaluate the contribution of microbial CUE to SOC variation. Microbial CUE increased with increasing aridity, whereas SOC declined, resulting in a weak negative relationship between CUE and SOC along the aridity gradient. This increase in CUE was primarily driven by reduced microbial respiration, while microbial growth remained largely unchanged. By contrast, correlation analyses revealed strong positive relationships between SOC and physicochemical protection, plant diversity and carbon inputs, edaphic properties, and microbial attributes. Random forest and structural equation models further showed that SOC variation was more strongly associated with indicators of physicochemical protection, including mineral-associated organic carbon, clay content, calcium-bound carbon, and microbial residue carbon than with microbial CUE. Together, our findings challenge the view that microbial CUE alone governs SOC accumulation and highlight the importance of stabilization processes in regulating SOC variations across the aridity gradient.
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BibTeX
@article{pan2026physicochemical,
title = {{Physicochemical Protection Outweighs Microbial Carbon Use Efficiency in Regulating Soil Organic Carbon Across an Aridity Gradient}},
author = {Junxiao Pan and Xianjin He and Jinsong Wang and Zhenrui Zhang and Jiashao Bai and Zijian Guo and Kunwei Wang and Han Zheng and Yifei Peng and Ruiyang Zhang and Xinyu Zhang and Shuli Niu},
journal = {Global Change Biology},
year = {2026},
month = sep,
doi = {10.1111/gcb.71138},
url = {https://hal.science/hal-05820793v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Physicochemical Protection Outweighs Microbial Carbon Use Efficiency in Regulating Soil Organic Carbon Across an Aridity Gradient
AU - Junxiao Pan
AU - Xianjin He
AU - Jinsong Wang
AU - Zhenrui Zhang
AU - Jiashao Bai
AU - Zijian Guo
AU - Kunwei Wang
AU - Han Zheng
AU - Yifei Peng
AU - Ruiyang Zhang
AU - Xinyu Zhang
AU - Shuli Niu
PY - 2026
DA - 2026/09/30
JO - Global Change Biology
DO - 10.1111/gcb.71138
UR - https://hal.science/hal-05820793v1
AB - Microbial carbon use efficiency (CUE) has been proposed as a critical determinant of soil organic carbon (SOC) dynamics, yet its relative importance compared with plant carbon inputs, edaphic conditions, microbial attributes, and physicochemical protection remains poorly understood. Here, we conducted large-scale soil samplings across a 3000-km aridity gradient on the Tibetan Plateau to evaluate the contribution of microbial CUE to SOC variation. Microbial CUE increased with increasing aridity, whereas SOC declined, resulting in a weak negative relationship between CUE and SOC along the aridity gradient. This increase in CUE was primarily driven by reduced microbial respiration, while microbial growth remained largely unchanged. By contrast, correlation analyses revealed strong positive relationships between SOC and physicochemical protection, plant diversity and carbon inputs, edaphic properties, and microbial attributes. Random forest and structural equation models further showed that SOC variation was more strongly associated with indicators of physicochemical protection, including mineral-associated organic carbon, clay content, calcium-bound carbon, and microbial residue carbon than with microbial CUE. Together, our findings challenge the view that microbial CUE alone governs SOC accumulation and highlight the importance of stabilization processes in regulating SOC variations across the aridity gradient.
SN - 1354-1013
SN - 1365-2486
ER -