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Modelling the dynamic physical protection of soil organic carbon: Insights into carbon predictions and explanation of the priming effect
Author(s) -
Luo Zhongkui,
Baldock Jeff,
Wang Enli
Publication year - 2017
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.13793
Subject(s) - soil carbon , decomposition , carbon fibers , priming (agriculture) , biological system , chemistry , underpinning , environmental science , carbon cycle , interaction , soil water , environmental chemistry , soil science , mathematics , ecology , statistics , agronomy , ecosystem , engineering , algorithm , organic chemistry , biology , civil engineering , germination , composite number
The role and significance of physically protected soil organic carbon ( SOC ) in regulating SOC dynamics remains unclear. Here, we developed a simple theoretical model ( DP model) considering dynamic physical protection to simulate the dynamics of protected ( C p ) and unprotected SOC ( C u ), and compared the modelling results with a conventional two‐pool (fast vs. slow) model considering chemical recalcitrance. The two models were first constrained using extensive SOC data collected from soils with and without fresh carbon (C) inputs under incubation conditions, and then applied to project SOC dynamics and explore mechanisms underpinning the priming effect ( PE ). Overall, both models explained more than 99% of the variances in observed SOC dynamics. The DP model predicted that C p accounted for the majority of total SOC . As decomposition proceeds, the proportion of C p reached >90% and kept relatively constant. Although the similar performance of the two models in simulating observed total SOC dynamics, their predictions of future SOC dynamics were divergent, challenging the predictions of widely used pool‐based models. The DP model also suggested alternative mechanisms underpinning the priming of SOC decomposition by fresh C inputs. The two‐pool model suggested that the PE was caused by the stimulated decomposition rates, especially for the slow recalcitrant pool, while the DP model suggested that the PE might be the combined consequence of stimulated C u decomposition, the liberation of C p to decomposition and the inhibition of the protection of unprotected SOC . The model‐data integration provided a new explanation for the PE , highlighting the importance of liberation of initially physically protected SOC to decomposition by new C inputs. Our model‐data integration demonstrated the importance of simulating physical protection processes for reliable SOC predictions, and provided new insights into mechanistic understanding of the priming effect.