Global grasslands can sequester soil organic carbon(SOC)while maintaining ecosystem function,thereby mitigating climate change.SOC consists of components with varying stability and turnover rates,such as particulate o...Global grasslands can sequester soil organic carbon(SOC)while maintaining ecosystem function,thereby mitigating climate change.SOC consists of components with varying stability and turnover rates,such as particulate organic carbon(POC)and mineral-associated organic carbon(MAOC).While these components have been extensively studied in the surface layer(0-30 cm),their distribution and controls in deeper layers remain poorly understood.This study combined precise measurements of POC and MAOC across seven sequential depth layers down to 2 m at 17 Inner Mongolian grassland sites with a global dataset to elucidate their vertical distribution patterns and underlying controls.Results showed that POC generally dominated MAOC in Inner Mongolian grassland soils,albeit with regional variations in this dominance.Interestingly,the proportion of MAOC to total SOC(MAOC:(MAOC+POC)),indicating SOC stability,increased with depth in the upper 0-50 cm but decreased below 50 cm,suggesting that environmental factors at depth may constrain POC decomposition and MAOC formation.POC accumulation was positively influenced by the mean annual precipitation in the top 30 cm and negatively affected by soil pH down to 50 cm.Contrastingly,MAOC was coregulated by the clay and silt content(CS)and aluminum(Al)oxide in surface soils(0-30 cm),whereas Al oxide dominated from 30 to 100 cm.Notably,MAOC:(MAOC+POC)correlated significantly with CS across all depths,underscoring the persistent role of physical protection mechanisms in deeper layers.These findings highlight depthspecific accumulation patterns and controls of POC and MAOC in the Inner Mongolian grasslands,indicating that optimizing SOC sequestration under changing climate and management scenarios requires depth-specific strategies that target both shortterm POC enhancement and long-term MAOC stabilization.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42375116&32241036)。
文摘Global grasslands can sequester soil organic carbon(SOC)while maintaining ecosystem function,thereby mitigating climate change.SOC consists of components with varying stability and turnover rates,such as particulate organic carbon(POC)and mineral-associated organic carbon(MAOC).While these components have been extensively studied in the surface layer(0-30 cm),their distribution and controls in deeper layers remain poorly understood.This study combined precise measurements of POC and MAOC across seven sequential depth layers down to 2 m at 17 Inner Mongolian grassland sites with a global dataset to elucidate their vertical distribution patterns and underlying controls.Results showed that POC generally dominated MAOC in Inner Mongolian grassland soils,albeit with regional variations in this dominance.Interestingly,the proportion of MAOC to total SOC(MAOC:(MAOC+POC)),indicating SOC stability,increased with depth in the upper 0-50 cm but decreased below 50 cm,suggesting that environmental factors at depth may constrain POC decomposition and MAOC formation.POC accumulation was positively influenced by the mean annual precipitation in the top 30 cm and negatively affected by soil pH down to 50 cm.Contrastingly,MAOC was coregulated by the clay and silt content(CS)and aluminum(Al)oxide in surface soils(0-30 cm),whereas Al oxide dominated from 30 to 100 cm.Notably,MAOC:(MAOC+POC)correlated significantly with CS across all depths,underscoring the persistent role of physical protection mechanisms in deeper layers.These findings highlight depthspecific accumulation patterns and controls of POC and MAOC in the Inner Mongolian grasslands,indicating that optimizing SOC sequestration under changing climate and management scenarios requires depth-specific strategies that target both shortterm POC enhancement and long-term MAOC stabilization.
