College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China.
Soil & Landscape Science, School of Molecular & Life Sciences, Faculty of Science & Engineering, Curtin University, Perth, WA, Australia.
Glob Chang Biol. 2020 Aug;26(8):4614-4625. doi: 10.1111/gcb.15157. Epub 2020 May 31.
Soil organic carbon (SOC), the largest terrestrial carbon pool, plays a significant role in soil-related ecosystem services such as climate regulation, soil fertility and agricultural production. However, its fate under land use change is difficult to predict. A major issue is that SOC comprised of numerous organic compounds with potentially distinct and poorly understood turnover properties. Here we use spatiotemporal measurements of the particulate (POC), mineral-associated (MOC) and charred SOC (COC) fractions from 176 trials involving changes in land use to assess their underlying controls. We find that the initial pool sizes of each of the three fractions consistently and dominantly control their temporal dynamics after changes in land use (i.e. the baseline effects). The effects of climate, soil physicochemical properties and plant residues, however, are fraction- and time-dependent. Climate and soil properties show similar importance for controlling the dynamics of MOC and COC, while plant residue inputs (in term of their quantity and quality) are much less important. For POC, plant residues and management practices (e.g. the frequency of pasture in crop-pasture rotation systems) are substantially more important, overriding the influence of climate. These results demonstrate the pivotal role of measuring SOC composition and considering fraction-specific stabilization and destabilization processes for effective SOC management and reliable SOC predictions.
土壤有机碳（SOC）是最大的陆地碳库，在与土壤相关的生态系统服务中起着重要作用，如气候调节、土壤肥力和农业生产。然而，其在土地利用变化下的命运难以预测。一个主要问题是 SOC 由许多有机化合物组成，这些化合物具有潜在的不同和理解不佳的周转特性。在这里，我们使用涉及土地利用变化的 176 个试验中颗粒态（POC）、矿物结合态（MOC）和炭化 SOC（COC）分数的时空测量值来评估其潜在的控制因素。我们发现，这三个分数中的每一个的初始池大小在土地利用变化后都一致且主要控制其时间动态（即基线效应）。然而，气候、土壤物理化学性质和植物残体的影响是分数和时间依赖性的。气候和土壤性质对控制 MOC 和 COC 的动态具有相似的重要性，而植物残体输入（就其数量和质量而言）则不那么重要。对于 POC，植物残体和管理实践（例如，在作物-牧草轮作系统中牧场的频率）则更为重要，这会忽略气候的影响。这些结果表明，对于有效的 SOC 管理和可靠的 SOC 预测，测量 SOC 组成并考虑分数特异性的稳定和不稳定过程至关重要。
