A new approach to simulate peat accumulation, degradation and stability in a global land surface scheme (JULES vn5.8_accumulate_soil)
A new approach to simulate peat accumulation, degradation and stability in a global land surface scheme (JULES vn5.8_accumulate_soil)
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全球陆面方案（JULES vn5.8_accumulate_soil）中模拟泥炭积累、退化和稳定性的新方法
DOI：
10.5194/gmd-2021-263
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发表时间：
2021-10
期刊：
影响因子：
16
通讯作者：
S. Chadburn;E. Burke;A. Gallego-Sala;N. Smith;M. Bret-Harte;D. Charman;J. Drewer;C. Edgar
中科院分区：
文献类型：
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作者：
S. Chadburn;E. Burke;A. Gallego-Sala;N. Smith;M. Bret-Harte;D. Charman;J. Drewer;C. Edgar
抽象的。泥炭地在地球系统模型（ESM）中经常被忽视。在包括它们的地方，它们通常通过一个单独的、规定的网格单元分数来表示，该网格单元分数被赋予泥炭（高有机）土壤的物理特性。然而，在现实中，土壤在纯矿物土壤（无有机材料）和纯有机土壤之间的光谱上变化，通常在矿物土壤下面覆盖可变厚度的有机层。它们也是动态的，有机层的厚度及其性质随着时间的推移而变化。目前的紧急状态措施既不能反映土壤类型的范围，也不能反映其动态性质。在这里，我们提出了一个新版本的ESM陆面计划（联合英国陆地环境模拟器，JULES），土壤有机质积累-从而泥炭地的形成，退化和稳定性-是集成在垂直分辨率的土壤碳计划。我们还介绍了跟踪土壤碳年龄作为深度的函数在朱尔斯的能力，并比较这测量泥炭年龄深度剖面。该方案模拟了土壤有机物质与其热力学和水力学特性之间的动态反馈。我们表明，排水泥炭地可以导致显着的碳损失沿着与土壤压实和泥炭性质的变化。然而，负反馈可能导致泥炭地在排水后重新湿润。这些生态水文反馈也可以导致泥炭地保持自己的气候，否则泥炭形成不会在模型中启动，即显示一定程度的弹性。新的模型产生类似的结果，原来的模型矿物土壤，和现实的土壤有机碳的泥炭地。特别是，当与基于全球泥炭核心数据集的216个地点的典型泥炭剖面相比时，表现最好的配置在泥炭地点的碳密度的均方根误差（RMSE）为7.7-16.7 kgC m−3，取决于气候带。这个误差比土壤碳本身（约30-60 kgC m−3）小得多，与标准JULES相比减少了35- 80%。矿物质土壤站点的RMSE在JULES-Peat中也比JULES本身小（减少约30- 50%）。因此，JULES-Peat可以作为一个完整的方案，模拟有机和矿物土壤。它不需要任何额外的输入数据，并为模型引入最少的额外变量。这提供了一种新的方法来改善有机和泥炭地土壤的模拟，并在ESM中相关的碳循环反馈，其他陆面模型可以遵循。
Abstract. Peatlands have often been neglected in Earth System Models (ESMs). Where they are included, they are usually represented via a separate, prescribed grid cell fraction that is given the physical characteristics of a peat (highly organic) soil. However, in reality soils vary on a spectrum between purely mineral soil (no organic material), and purely organic soil, typically with an organic layer of variable thickness overlying mineral soil below. They are also dynamic, with organic layer thickness and its properties changing over time. Neither the spectrum of soil types nor their dynamic nature can be captured by current ESMs. Here we present a new version of an ESM land surface scheme (Joint UK Land Environment Simulator, JULES) where soil organic matter accumulation - and thus peatland formation, degradation and stability – is integrated in the vertically-resolved soil carbon scheme. We also introduce the capacity to track soil carbon age as a function of depth in JULES, and compare this to measured peat age-depth profiles. This scheme simulates dynamic feedbacks between the soil organic material and its thermal and hydraulic characteristics. We show that draining the peatlands can lead to significant carbon loss along with soil compaction and changes in peat properties. However, negative feedbacks can lead to the potential for peatlands to rewet themselves following drainage. These ecohydrological feedbacks can also lead to peatlands maintaining themselves in climates where peat formation would not otherwise initiate in the model, i.e. displaying some degree of resilience. The new model produces similar results to the original model for mineral soils, and realistic profiles of soil organic carbon for peatlands. In particular the best performing configurations had root mean squared error (RMSE) in carbon density for peat sites of 7.7–16.7 kgC m−3 depending on climate zone, when compared against typical peat profiles based on 216 sites from a global dataset of peat cores. This error is considerably smaller than the soil carbon itself (around 30–60 kgC m−3) and reduced by 35–80 % compared with standard JULES. The RMSE at mineral soil sites is also smaller in JULES-Peat than JULES itself (reduced by ~30–50 %). Thus JULES-Peat can be used as a complete scheme that simulates both organic and mineral soils. It does not require any additional input data and introduces minimal additional variables to the model. This provides a new approach for improving the simulation of organic and peatland soils, and associated carbon-cycle feedbacks in ESMs, which other land surface models could follow.