Department of Life Sciences, Imperial College London, London, UK.
Department of Biology, Utah State University, Logan, Utah, USA.
Glob Chang Biol. 2024 Sep;30(9):e17507. doi: 10.1111/gcb.17507.
Soil organic carbon (SOC) sequestration is increasingly emphasized as a climate mitigation solution, as scientists, policy makers, and land managers prioritize enhancing belowground C storage. To identify key underlying drivers of total SOC distributions, we compiled a global dataset of soil C stocks held in three chemical forms, reflecting different mechanisms of organic C protection: free particulate organic C (fPOC), physically protected particulate organic C (oPOC), and mineral-protected soil organic C (mSOC). In our dataset, these three SOC pools were differentially sensitive to the effects of climate, soil mineralogy, and ecosystem type, emphasizing the importance of distinguishing between physical and chemical C protection mechanisms. C stocks in all three pools varied among ecosystems: cropland soils stored the least amount in each pool, with forest and grassland soils both containing significantly more fPOC (40%-60% greater in each ecosystem) than croplands. oPOC stocks did not significantly differ from zero in croplands but were substantial in forest and grassland soils. Meanwhile, mSOC stocks were the greatest in grasslands and shrublands (90%-100% greater than croplands). In cropland soils, there were no major effects of tillage on C storage in any of the three pools, while manure addition enhanced mSOC stocks, especially when added with inorganic N. Thus, the human land use intensity in croplands appears to reduce SOC storage in all major pools, depending upon management; retaining native vegetation should be emphasized to maintain current global SOC stocks.
土壤有机碳（SOC）固存作为一种气候缓解解决方案，越来越受到重视，因为科学家、政策制定者和土地管理者优先考虑增强地下碳储存。为了确定总 SOC 分布的关键潜在驱动因素，我们编制了一个全球土壤碳储量数据集，这些储量以三种化学形式存在，反映了有机碳保护的不同机制：游离颗粒有机碳（fPOC）、物理保护颗粒有机碳（oPOC）和矿物保护土壤有机碳（mSOC）。在我们的数据集，这三个 SOC 库对气候、土壤矿物学和生态系统类型的影响存在差异敏感性，强调区分物理和化学碳保护机制的重要性。所有三个库中的碳储量在生态系统之间存在差异：农田土壤在每个库中储存的碳最少，森林和草地土壤的 fPOC 含量均明显高于农田（每个生态系统中分别高出 40％-60％）。oPOC 储量在农田中没有明显的零值，但在森林和草地土壤中则相当可观。与此同时，mSOC 储量在草地和灌木地中最大（比农田高出 90％-100％）。在农田土壤中，三种库中没有任何耕作对 C 储存的主要影响，而添加有机肥增加了 mSOC 储量，特别是在添加无机 N 的情况下。因此，人类在农田中的土地利用强度似乎取决于管理方式，降低了所有主要库中的 SOC 储量；应该强调保留本地植被，以维持当前全球 SOC 储量。
