CSIRO Agriculture & Food, Canberra, Australia.
CSIRO Agriculture & Food, Glen Osmond, Australia.
Glob Chang Biol. 2017 Dec;23(12):5273-5283. doi: 10.1111/gcb.13793. Epub 2017 Jul 8.
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 ) and unprotected SOC (C ), 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 accounted for the majority of total SOC. As decomposition proceeds, the proportion of C 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 decomposition, the liberation of C 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.
物理保护土壤有机碳（SOC）在调节 SOC 动态方面的作用和意义尚不清楚。在这里，我们开发了一个简单的理论模型（DP 模型），考虑了动态物理保护，以模拟受保护的（C）和不受保护的 SOC（C）的动态，并将建模结果与考虑化学抗降解性的传统两库（快速与慢速）模型进行了比较。这两个模型首先使用在培养条件下具有和不具有新鲜碳（C）输入的土壤中收集的广泛 SOC 数据进行约束，然后应用于预测 SOC 动态并探索引发效应（PE）的机制。总体而言，两个模型都解释了观察到的 SOC 动态的 99%以上的方差。DP 模型预测 C 占总 SOC 的大部分。随着分解的进行，C 的比例达到>90%并保持相对稳定。尽管两个模型在模拟观察到的总 SOC 动态方面具有相似的性能，但它们对未来 SOC 动态的预测却存在分歧，这对广泛使用的基于库的模型的预测提出了挑战。DP 模型还提出了由新鲜 C 输入引发 SOC 分解的替代机制。两库模型表明，PE 是由分解速率的刺激引起的，特别是对于缓慢的抗降解库，而 DP 模型则表明，PE 可能是刺激的 C 分解、C 的释放以及对未受保护的 SOC 保护的抑制的综合结果。模型-数据集成提供了对 PE 的新解释，强调了新的 C 输入对分解的最初物理保护 SOC 的释放的重要性。我们的模型-数据集成证明了模拟物理保护过程对可靠 SOC 预测的重要性，并为对引发效应的机制理解提供了新的见解。
