The current soil carbon paradigm puts particulate organic carbon (POC) as one of the major components of soil organic carbon worldwide, highlighting its pivotal role in carbon mitigation. In this study, we compiled a global dataset of 3418 data points of POC concentration in soils and applied empirical modeling and machine learning algorithms to investigate the spatial variation in POC concentration and its controls. The global POC concentration in topsoil (0–30 cm) is estimated as 3.02 g C/kg dry soil, exhibiting a declining trend from polar regions to the equator. Boreal forests contain the highest POC concentration, averaging at 4.58 g C/kg dry soil, whereas savannas exhibit the lowest at 1.41 g C/kg dry soil. We developed a global map of soil POC density in soil profiles of 0‐30 cm and 0–100 cm with an empirical model. The global stock of POC is 158.15 Pg C for 0–30 cm and 222.75 Pg C for 0–100 cm soil profiles with a substantial spatial variation. Analysis with a machine learning algorithm concluded the predominate controls of edaphic factors (i.e., bulk density and soil C content) on POC concentration across biomes. However, the secondary controls vary among biomes, with solid climate controls in grassland, pasture, and shrubland, while strong vegetation controls in forests. The biome‐level estimates and maps of POC density provide a benchmark for modeling C fractions in soils; the various controls on POC suggest incorporating biological and physiochemical mechanisms in soil C models to assess and forecast the soil POC dynamics in response to global change.

中文翻译：

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全球土壤中颗粒有机碳的主要 Edaphic 控制


目前的土壤碳范式将颗粒有机碳 （POC） 视为全球土壤有机碳的主要成分之一，凸显了其在碳减排中的关键作用。在这项研究中，我们编译了一个包含土壤中 POC 浓度 3418 个数据点的全球数据集，并应用经验建模和机器学习算法来研究 POC 浓度及其控制的空间变化。表层土壤 （0-30 cm） 中的全球 POC 浓度估计为 3.02 g C/kg 干土，从极地地区到赤道呈下降趋势。北方森林的 POC 浓度最高，平均为 4.58 g C/kg 干土，而稀树草原的干土含量最低，为 1.41 g C/kg 干土。我们使用实证模型制作了 0-30 cm 和 0-100 cm 土壤剖面中土壤 POC 密度的全球地图。全球 POC 储量为 0-30 cm 的 158.15 Pg C 和 0-100 cm 土壤剖面的 222.75 Pg C，空间差异很大。使用机器学习算法进行的分析得出结论，edaphic 因素（即堆积密度和土壤 C 含量）对生物群落中 POC 浓度的主要控制。然而，二级控制因生物群落而异，草原、牧场和灌木丛具有坚实的气候控制，而森林中有强大的植被控制。POC 密度的生物群落水平估计和地图为土壤中 C 分数建模提供了基准;对 POC 的各种控制建议将生物和理化机制纳入土壤 C 模型，以评估和预测响应全球变化的土壤 POC 动态。