Soil Organic Carbon (SOC) Equilibrium and Model Initialisation Methods: an Application to the Rothamsted Carbon (RothC) Model
Soil Organic Carbon (SOC) Equilibrium and Model Initialisation Methods: an Application to the Rothamsted Carbon (RothC) Model
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DOI：
10.1007/s10666-016-9536-0
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发表时间：
2017-06
影响因子：
2.4
通讯作者：
Nemo;K. Klumpp;K. Coleman;M. Dondini;K. Goulding;A. Hastings;MICHAEL B. Jones;J. Leifeld;
中科院分区：
文献类型：
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作者：
Nemo;K. Klumpp;K. Coleman;M. Dondini;K. Goulding;A. Hastings;MICHAEL B. Jones;J. Leifeld;
人类土地利用产生的碳排放加速了气候变化。为了减少碳排放，可以使用动态模型来评估人类驱动因素对陆地碳固存的影响。模型精度需要正确的初始化，因为不正确的初始化会影响获得的结果。因此，我们试图改善初始化的过程为基础的SOC模型，RothC，它可以估计气候和土地利用变化对SOC的影响。最常见的初始化涉及运行模型，直到平衡（“自旋运行”），当SOC池稳定（方法1）。然而，这种方法并不总是产生现实的结果。在我们的实验地点，所观察到的SOC在10年后没有达到平衡，这表明通常使用的假设平衡的自旋初始化方法可能会得到改进。除了方法1之外，我们还测试了RothC的两种替代初始化，其涉及通过在整个启动初始化期间调节C输入来调整总的或单个SOC池平衡值（方法2），以及使用通过SOC分馏获得的最近测量的SOC值来初始化每个SOC池（方法3）。对每个模型初始化的模拟精度进行分析，使用均方根误差（RMSE）进行量化，表明方法2的一个变体涉及将平衡总SOC调整为观测值（方法2-T）通常显示单个SOC库和总SOC的变化较小。此外，由于总SOC是所有SOC库的总和，由于总SOC数据比单个SOC池数据更容易获得，我们得出结论，方法2-T最适合于初始化RothC。
Carbon (C) emissions from anthropogenic land use have accelerated climate change. To reduce C emissions, dynamic models can be used to assess the impact of human drivers on terrestrial C sequestration. Model accuracy requires correct initialisation, since incorrect initialisation can influence the results obtained. Therefore, we sought to improve the initialisation of a process-based SOC model, RothC, which can estimate the effect of climate and land-use change on SOC. The most common initialisation involves running the model until equilibrium (‘spin-up run’), when the SOC pools stabilise (method 1). However, this method does not always produce realistic results. At our experimental sites, the observed SOC was not at equilibrium after 10 years, suggesting that the commonly used spin-up initialisation method assuming equilibrium might be improved. In addition to method 1, we tested two alternative initialisations for RothC that involved adjusting the total or individual SOC pool equilibrium values by regulating the C input during the entire spin-up initialisation period (method 2) and initialising each SOC pool with recently measured SOC values obtained by SOC fractionation (method 3). Analysis of the simulation accuracy for each model initialisation, quantified using the root mean square error (RMSE), indicated that a variant of method 2 that involved adjusting the equilibrium total SOC to observed values (method 2-T) generally showed less variation in the individual SOC pools and total SOC. Furthermore, as total SOC is the sum of all SOC pools, and because total SOC data are more readily available than the individual SOC pool data, we conclude that method 2-T is best for initialising RothC.